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  • Column on Severe Respiratory Infection in Children
    LI Tian, FAN Huifeng, YANG Zhiyong, LU Xiulan, WU Yuhui, LI Musheng, ZHANG Jianhui, HUANG Li
    China Tropical Medicine. 2024, 24(7): 761-766. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.01

    Objective To explore the clinical data of children with Talaromyces marneffei (TM) infection admitted to the pediatric intensive care unit (PICU) to improve the diagnosis and treatment of TM infection in children. Methods The clinical data of 23 children with TM infection treated in four PICUs in southern China from January 2013 to December 2022 were retrospectively analyzed, including clinical characteristics, laboratory tests, treatment regimens, and outcomes. Results Among the 23 children, there were 14 boys and 9 girls, with a median age of 24 months. The time from onset to admission was 15 (range 10-30) days, and one patient had immunodeficiency disease. Common symptoms included fever (91.3%, 21 cases), cough (78.3%, 18 cases), and hepatosplenomegaly (78.3%, 18 cases). Severe clinical complications included multiorgan dysfunction (69.6%, 16 cases), septic shock (65.2%, 15 cases), and acute respiratory distress syndrome (65.2%, 15 cases). All patients elevated CRP levels, and 69.2% (9/13) had a positive G test. Elevated IgE levels were observed in 53.3% (8/15) cases, CD4/CD8 inversion in 17.6% (3/17) cases, and reduced NK cells in 84.2% (16/19) cases. HIV tests were negative in all cases. TM was most frequently detected by blood and bone marrow cultures. Seven cases were diagnosed with immunodeficiency by genetic testing. With monotherapy or combination of amphotericin B or/and voriconazole, followed by oral medication, 13 (56.5%) children died. Conclusions TM infection is clinically atypical in HIV-negative children, and patients admitted to PICU have rapidly deteriorated, with severe complications and a high mortality rate. Early use of multiple samples, and multiple methods to detect TM, combined with immune function and genetic test, is helpful to early diagnosis. The antifungal treatment strategies still need further study.

  • Column on Dengue Fever Prevention and Control
    LI Zhuowei, HUANG Xiaoxia, TIAN Tingting, LI A Qian, Du Shanshan, HE Guangxue, LI Jiandong
    China Tropical Medicine. 2024, 24(8): 925-930. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.07

    Objective To analyze the epidemiological characteristics of reported cases of dengue fever in mainland China from 2019 to 2023 and provide a scientific basis for dengue prevention and control efforts. Methods The temporal, spatial, and population distribution characteristics, as well as the trends of dengue fever cases reported in the National Notifiable Disease Reporting System (NNDRS) of China were analyzed using software such as Joinpoint regression, SaTScan, and ArcGIS. Results From 2019 to 2023, a total of 43 095 cases were reported in China, with an average incidence rate of 61/100 000. The annual reported incidence rate fluctuated significantly (AAPC=-3.16%, 95%CI:-54.16%-91.47%), mainly concentrated in 2019 and 2023, accounting for 96.83% of the total reported cases over the past five years. All age groups were susceptible to the disease, with the 30 to <40 age group comprising 22.6% of cases. Cases were reported throughout the year, with a rapid increase starting in June and a peak period concentrated between August and October (n=34 780, RR=12.44, LLR=29 262.52, P<0.05). The epidemic was primarily characterized by imported cases leading to autochthonous transmission, with the majority of imported cases originating from Southeast Asia (86.56%), particularly from Cambodia (46.11%, 3 284 cases) and Myanmar (25.99%, 1 851 cases). The epidemic characteristics varied significantly across different years, with high risks of autochthonous transmission epidemics in Southwest, South, and Southeast China. High-risk local transmission were mainly distributed in Yunnan and Guangdong. The duration of the peak period of the epidemic was affected by the timeliness of early detection of local transmission, and the peak value of the epidemic was related to the effectiveness of prevention and control measures. The scale of the epidemic was influenced by the pressure of by cross-border transmission and the ability to implement local measures for dengue prevention and control. Conclusions With the increasing trend of global dengue transmission, the risk of autochthonous transmission of dengue in China is rising. It is recommended to strengthen proactive early outbreak surveillance, along with well preparation of personnel, technology, and resources for dengue prevention and control.According to autochthonous conditions, reasonable management and risk assessment of cross-border travelers should be explored to effectively.

  • Articles
    MA Xinya, ZHOU Xingyu, YUAN Heng
    China Tropical Medicine. 2024, 24(9): 1149-1152. https://doi.org/10.13604/j.cnki.46-1064/r.2024.09.22

    Objective To analyze the epidemiological and clinical characteristics of confirmed mpox cases in Sichuan Province in 2023 and to provide a scientific basis for the prevention and control of the mpox epidemic, and provide reference for the prevention and control of other emerging infectious diseases. Methods The data were collected from the information of confirmed mpox cases residing in Sichuan Province reported in the National Infectious Disease Reporting Information Management System until 24:00 on December 31, 2023, as well as the epidemiological investigation report of mpox cases. Excel 2020 software was used to input, sort out and plot the data, SPSS 23 statistical software was used to analyze the data, and descriptive epidemiological methods were used to analyze the basic characteristics of the cases. Results The first mpox case was reported in Sichuan Province on June 30, 2023, and the peak period of reported cases was from July to August. As of December 31, 2023, a total of 141 mpox cases had been reported. The cases were predominantly male (99.3%), aged 30-<40 years (49.6%), and MSM (men who have sex with men, accounting for 93.0% of male cases). 35.4% of cases reported HIV infection. The interval from onset of symptoms to diagnosis ranged from 2 to 90 days, with M(P25P75) being 4 (6, 8) days. The incubation period for cases ranged from 1 to 21 days, with M(P25P75) being 7 (4, 10) days. The majority of cases were discovered through proactive medical consultation (96.4%). The initial symptoms were rash (70.9%) and fever (31.2%). The main symptoms were rash (95.7%), fever (55.3%), and lymph node enlargement (35.5%). Conclusion Mpox outbreaks mainly occur in MSM population. It is necessary to make full use of the comprehensive intervention service system for AIDS prevention and treatment to publicize and educate key groups, timely monitor the variation of monkeypox virus, especially strengthen the surveillance of inbound cases, implement early detection and control of cases, and reduce the risk of epidemic transmission.

  • Column on Dengue Fever Prevention and Control
    ZHAO Jin, ZHOU Yinzhu, CHEN Shuilian, QIU jinsong, YANG Xuewen
    China Tropical Medicine. 2024, 24(8): 920-924. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.06

    Objective To analyze the incidence trends and spatiotemporal distribution characteristics of dengue fever in China based on the data from the China Disease Control Information System and the "National Statutory Infectious Disease Epidemic Overview" published by the National Health Commission of the People's Republic of China, and to provide a scientific basis for the prevention and control of dengue fever epidemics. Methods The incidence rates and monthly case numbers of dengue fever in China from 2015 to 2023 were collected. Provinces were classified according to the severity of the epidemic and the distribution status of the Aedes vector. The incidence trends, seasonal distribution, and spatial aggregation of dengue fever in China were statistically analyzed. Results The top five provinces with the highest average annual incidence rates from 2015 to 2023 were Yunnan (6.16/100 000), Guangdong (1.70/100 000), Hainan (1.13/100 000), Fujian (1.13/100 000), and Chongqing (0.74/100 000). The average annual incidence rate of dengue fever in China increased by 70.79% from 2015 to 2019 (AAPC=70.79, P=0.045). In Class Ⅰ regions, the incidence of Guangxi and Hainan showed a linear regression trend, with average annual increases of 844.73% (AAPC=844.73, P=0.021) and 516.51% (AAPC=516.51, P=0.013), respectively. In Class Ⅱ regions, except for Shanghai, the incidence of other provinces showed a linear regression trend, with Jiangxi having the highest average annual increase of 610.16% (AAPC=610.16, P=0.021), followed by Chongqing at 345.12% (AAPC=345.12, P=0.038). In Class Ⅲ regions, the incidence of Hebei, Shanxi, and Liaoning had a linear regression trend, with average annual increases of 80.67% (AAPC=80.67, P=0.028), 202.31% (AAPC=202.31, P=0.001), and 70.19% (AAPC=70.19, P=0.031), respectively. The epidemic of dengue fever showed no obvious seasonality in 2021, strict seasonality in 2022, and strong seasonality in the rest of the years. The epidemic peak days were mostly concentrated in the middle and late September to early October of each year, and the epidemic peak periods were mainly concentrated in August-early November. From 2015 to 2018, the incidence rate had no spatial aggregation nationwide, and the incidence rate in 2019 had spatial aggregation nationwide. In 2015-2019 and 2023, there were no high-low gathering areas in the country, and high-high gathering areas appeared in 2018 (Fujian, Hainan) and 2019 (Guangxi). Conclusions The situation of dengue fever prevention and control in China is grim. High-risk epidemic areas of dengue fever will no longer be limited to Class Ⅰ provinces, and the risk of expansion to Class Ⅱ provinces is increasing.

  • Chronic Hepatitis B Prevention Study Column
    ZHANG Shaoquan, LIN Bingliang
    China Tropical Medicine. 2025, 25(3): 259-263. https://doi.org/10.13604/j.cnki.46-1064/r.2025.03.01

    Chronic hepatitis B (CHB) caused by the hepatitis B virus (HBV), constitutes a significant public health issue, with approximately 254 million individuals affected globally, of which 75 million are in China. HBV infection not only severely impacts individual health, leading to conditions such as liver cirrhosis, hepatocellular carcinoma, and liver failure, but also imposes considerable economic burdens on society. This review provides an overview of the current epidemiological characteristics and disease burden of CHB, along with the progress towards, and challenges faced in achieving the World Health Organization's (WHO) goal of eliminating viral hepatitis as a public health threat by 2030. It delves into strategies aimed at reducing new infections, enhancing diagnosis rates, and improving treatment coverage. These strategies include universal screening, expanding the scope of antiviral therapy, and implementing specific measures for treating patients with end-stage liver disease. The review underscores critical actions necessary to accelerate the elimination of hepatitis B-related harms, proposing an integrated control and prevention strategy that incorporates new technologies and approaches. Achieving WHO's 2030 target requires concerted efforts from governments, healthcare institutions, and the broader community, alongside active public participation and support.

  • Research Reports
    LI Binghui, ZHU Hailong, LI Song, FU Qiqi, MA Xiaofang, LIU Yantao, SUN Qintong
    China Tropical Medicine. 2024, 24(7): 875-879. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.20

    Objective To explore the application of factorial design in field trapping experiments for flies, and to provide more ideas for screening the best fly control method. Methods A 2×2 factorial design was used to analyze the main effects of the height of the fly cage (hanging fly cage, standing fly cage) and the type of bait (commercial bait, smelly tofu bait), and the interaction between the two factors. The fly trapping methods were divided into four combinations: hanging fly cage and commercial bait, hanging fly cage and smelly tofu bait, standing fly cage and commercial bait, standing fly cage and smelly tofu bait. The experiment was repeated 7 times for each combination and carried out according to the National Vector Biological Surveillance Implementation Plan. The best fly trapping method was identified by factorial design analysis of variance. Results A total of 2 296 flies were trapped in this study, with a cumulative deployment of 28 traps in the field, resulting in an average total density of 82.0 flies per cage. Among them, the number of flies attracted by the combination of standing fly cage and smelly tofu was the largest, accounting for 44.16% (1 014/2 296) of the total number of flies caught, with an average fly density of 144.8 flies per trap. This was followed by the combination of hanging fly cage and smelly tofu, hanging fly trap and commercial bait, and standing fly cage and commercial bait, accounting for 42.73% (981/2 296), 8.71% (200/2 296), and 4.40% (101/2 296) of the total, with average fly densities of 140.1, 28.6, and 14.4 flies per trap, respectively. The differences in field fly density among different trapping methods were statistically significant (F=49.441, P<0.001), and the differences in fly population composition were also statistically significant (χ2=259.980, P<0.001). The main effect of trap height was not significant (F=0.223, P=0.641), while the main effect of bait type was significant (F=147.206, P<0.001), and the interaction effect between trap height and bait type was not significant (F=0.894, P=0.354). Conclusions Compared with the single-factor design method, the factorial design method can not only analyze the main effects of each factor but also the interactions between the factors. The combination of standing fly cage and smelly tofu is preferred to have a better fly control effect.

  • Articles
    LIU Bowen, ZHANG Tao, LIU Jingshu, HUO Shiyi, XUE Jingbo, WANG Duoquan, XIA Zhigui, LI Weidong, LI Shizhu
    China Tropical Medicine. 2025, 25(1): 1-8. https://doi.org/10.13604/j.cnki.46-1064/r.2025.01.01

    Objective The objective of this research is to construct a technical indicator framework for preventing the of re-establishment of imported malaria at the county level in China, excluding border areas, with the aim of guiding specialist agencies to prevent the re-establishment of imported malaria in a scientific, feasible and comprehensive way. Methods The preliminary framework was built based on literature review and on-site research. Two rounds of Delphi consultation were carried out. The positive coefficient, degree of concentration, degree of coordination, and authority of the experts were calculated. The weights and the combined weights for the indicators were determined using the analytic hierarchy process and probability method, respectively. Results Twenty experts were invited in the 1st round of consultation, and twenty-six in the 2nd round. The authority coefficients of the experts for two rounds were 0.955 and 0.968, respectively. The P value of the degree of coordination of two rounds were less than 0.05. The final framework included 5 primary indicators, 19 secondary indicators and 42 tertiary indicators. Primary indicators included government-led, joint control and prevention, surveillance and response, capacity building and organization guarantee, whose weights were 20.2%, 2.4%, 20.1%, 44.7% and 12.5%, respectively. Among the secondary indicators, the highest combined weight was medical institutions (25.0%) of capacity building, and the lowest was cross-sectoral cooperation (0.3%) of joint control and prevention. The three tertiary indicators with higher combined weights were: "1.2.1 There is a comprehensive plan for preventing the re-establishment of imported malaria, and the responsibilities of relevant departments are clearly defined" accounting for 14.9%; "4.1.4 Laboratory personnel in medical institutions possess the ability to conduct microscopic examinations for malaria detection" accounting for 10.6%; and "4.2.1 Specialized malaria surveillance laboratories have been established and are fully equipped with the necessary capabilities to conduct effective surveillance" accounting for 7.6%. Conclusions A framework has been created for the prevention of re-establishment of imported malaria at the county level in China, excluding border areas. The framework provides an operational, scientific and comprehensive technical guidance for county-level areas from the perspective of the effectiveness of government-led, joint prevention and control, surveillance and response, capacity building and organizational support. The importance of maintaining the capacity to prevent re-establishment of imported malaria and whole-process case management under medical and preventive cooperation in the post-elimination stage was highlighted.

  • Original article
    BI Xiaojuan, YANG Ning, LI Liang, CHU Jin, LYU Guodong, LIN Renyong
    China Tropical Medicine. 2025, 25(2): 232-236. https://doi.org/10.13604/j.cnki.46-1064/r.2025.02.18

    Echinococcosis is a parasitic disease caused by the larval stage of Echinococcus tapeworms, posing a severe threat to patients' health. Its diagnostic techniques play a vital role in clinical diagnosis and treatment, surgical planning, and prognostic evaluation. Currently, the diagnostic methods for echinococcosis mainly include etiological, immunological, imaging, and molecular biological diagnostic techniques. This article comprehensively reviews existing diagnostic techniques for echinococcosis, analyzes the advantages and limitations of various methods, and explores their application prospects. With continuous advancements in scientific technology, emerging diagnostic approaches are expected to substantially enhance the efficiency and accuracy of echinococcosis diagnosis. These research findings will provide valuable references for the development of rapid clinical diagnostic detection products at the current stage, potentially improving cure rates, alleviating patients' disease burden, and offering robust support for the prevention, control, and treatment of echinococcosis.

  • Articles
    LIU Kaixuan, CAO Yuanyuan, CHONG Zeyin, CHAI Liying, ZHAO Li, LU Yan, ZHU Guoding, CAO Jun, LU Guangyu
    China Tropical Medicine. 2025, 25(1): 9-14. https://doi.org/10.13604/j.cnki.46-1064/r.2025.01.02

    Objective To identify the temporal-spatial distribution patterns and changing of hotspot areas of malaria importations, and high-risk importation areas for imported malaria in Jiangsu Province, in order to provide the scientific evidence for prevention of malaria reintroduction in China. Methods Cases with imported malaria in Jiangsu Province from 2016 to 2022 were accessed from the National Notifiable Disease Report System and the Information Management System for Parasitic Disease Control in China. The county-level vector map of Jiangsu Province was obtained from the National Fundamental Geographic Information System, China. ArcGIS 10.7 software was utilized to create a thematic map depicting the distribution of imported malaria cases in Jiangsu Province at the county level. Global and local autocorrelation analysis was then conducted to investigate the spatiotemporal changes in malaria import hotspot counties. Results There were a total of 1 189 cases with imported malaria reported in 77 counties (81.05%, 77/95) of Jiangsu Province from 2016 to 2022. The global spatial autocorrelation analysis showed that a global spatial cluster of imported malaria in Jiangsu was only identified in 2020 ( Moran's I =0.46, Z=4.37, P<0.01), but local spatial autocorrelation analysis found that a total 60 hotspot counties existed from 2016 to 2022. There are 23 counties in central Jiangsu (38.33%), and 20 counties in southern Jiangsu (33.33%), 17 counties in northern Jiangsu (28.33%). The distribution of hotspot counties exhibits continuity. For instance, Chongchuan District, which falls under the jurisdiction of Nantong City, has consistently emerged as a hotspot county for 2016-2021. Since 2020, two recurring hotspot counties emerged in northern Jiangsu and southern Jiangsu. These counties are Ganyu District, under the jurisdiction of Lianyungang City, and Lishui District, under the jurisdiction of Nanjing City. Conclusions The spatial-temporal cluster of cases with imported malaria was identified at the county level in Jiangsu, that hotspot counties were consistently detected. It is essential to maintain the sustainability of malaria surveillance and response in hotspot counties which were new detected, and strengthen the capacity of surveillance and response in hotspot counties which were continually detected based on the spatial-temporal distribution characteristics and changing rules of imported malaria.

  • Articles
    LIU Xinyu, HE Jian, HE Chunna, LI Zihan, HUANG Yajing, CHEN Biyu, HU Yuehua, YIN Dapeng
    China Tropical Medicine. 2025, 25(3): 316-322. https://doi.org/10.13604/j.cnki.46-1064/r.2025.03.10

    Objective To analyze the epidemiological characteristics of varicella infectious diseases in Hainan Province from 2014 to 2023, and explore the epidemic patterns of varicella in Hainan Province. Methods Download data related to chickenpox in Hainan Province from the Infectious Disease Reporting Information Management System and the Public Health Emergency Management System of the Chinese Disease Control and Prevention Information System, descriptive epidemiological methods were used to analyze the incidence characteristics of varicella; ARIMA model was used to predict the incidence trend. Results From 2014 to 2023, a total of 65 832 cases of varicella and one death case were reported in Hainan, with an average annual incidence rate of 66.50/100 000, and the incidence rate fluctuated between 47.31/100 000 and 89.01/100 000. A incidence rate peak occurred every other year. The incidence of varicella showed a seasonal bimodal distribution, with peaks in January and April. The incidence of varicella was negatively correlated with temperature (r=-0.349,P<0.05). Children aged 0-14 years were the main incidence group, and the incidence rate reached its peak in the age group of 5-6 years. Students and young children were the main groups affected by the disease. The incidence rate of male (68.15/100 000) was higher than that of female (62.22/100 000)(χ2=16.80, P<0.05). The incidence rate of male (68.15/100 000) was higher than that of female (62.22/100 000). The 1 dose vaccination rate for 1-year-old children was on the rise, reaching a maximum of 43.2%; The two doses vaccination rate for children aged 4-6 years has been increasing year by year, with the highest reaching 9.9%. A total of 65 cases of varicella PHEE were reported, with M(P25, P75) of 24 (18, 32) cases per case, and a total incidence rate of 2.64%. Primary schools were the main places of occurrence. The ARIMA model has a good predictive fitting effect, and the results show that the predicted incidence in 2024 will increase compared to 2023. There may be peaks in incidence in January to June and October to December. Conclusions The incidence rate of varicella is high in Hainan Province; A lower vaccination rate for varicella in children cannot break the natural prevalence of varicella among healthy children.

  • Column on Severe Respiratory Infection in Children
    WU Yuhui, QIU Jieting
    China Tropical Medicine. 2024, 24(7): 796-801. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.07

    Acute viral respiratory tract infections, particularly acute viral lower respiratory tract infections, are a prevalent etiology of severe pediatric respiratory illness. In addition to the harm caused by viral replication itself, excessive inflammatory responses and immune homeostasis imbalances in the body can trigger cytokine storms, resulting in severe tissue and organ damage, and leading to multiple organ dysfunction or even mortality. With the continuous promotion and application of various etiological detection techniques in clinical practice, early and accurate diagnosis of the virus can be achieved. Reasonable selection of antiviral drugs, standardized implementation of non-drug intervention measures, and active immunization are helpful to prevent and control infection.

  • Column on Dengue Fever Prevention and Control
    ZHANG Wei, LIU Wenhui, ZHEN Ruonan, LU Ying, DAI Bofeng, RAN Rui, LIAO Xinlong, LUO Lei
    China Tropical Medicine. 2024, 24(8): 955-960. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.12

    Objective To analyze the epidemiological characteristics of dengue fever in Guangzhou and provide a scientific basis for dengue fever prevention and control. Methods The data of dengue cases in Guangzhou, Guangdong Province reported between 2019 and 2023, were retrieved from the China Disease Prevention and Control Information System. Cross-sectional analysis was used to describe the temporal, spatial, and demographic distribution, and analyze the epidemiological characteristics. Results A total of 3 518 cases of dengue fever were reported in Guangzhou from 2019 to 2023, including 3 101 local cases (88.15%) and 417 imported cases (11.85%). The annual average incidence rate ranged from 0.09 to 17.59 per 100 000 population. Imported dengue fever cases were reported in all months, with the peak reported from May to November (374 cases, 89.69%). Local cases were first reported in May and the last in December, with the highest incidence from August to November (2 960 cases, 95.45%). The cases were reported in all 11 administrative districts; the top three were Baiyun District, Yuexiu District, and Liwan District. Male and female cases accounted for 53.52% and 46.48%, respectively; the age group mainly concentrated between 20-<60 years (2 547 cases, 72.40%). The top three occupations were business services (784 cases), housework and unemployment (738 cases), and retirees (596 cases). The average time from onset to diagnosis for local cases was 4.06 days, and 4.60 days for imported cases. The overseas imported cases mainly came from Southeast Asia 88.10%(311/353), with the most being imported from Cambodia. Cases imported from other provinces mainly came from Yunnan Province, and cases imported from other cities within the province mainly came from Foshan City. Conclusions In recent years, the incidence of dengue fever in Guangzhou has remained at a high level, with obvious imported and seasonal characteristics. Relevant departments should pay attention to key populations and take effective measures to reduce the density of mosquito vectors, and strictly prevent the spread of dengue fever.

  • Column on Dengue Fever Prevention and Control
    OUYANG Hanqi, ZHAO Ziyu, HONG Li, BAI Li, MENG Weiwei, LIN Zhuohang, YANG Guojing
    China Tropical Medicine. 2024, 24(8): 900-906. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.03

    Objective To analyze the changing trends of severe dengue (SD) among adults and children in China and compare the clinical manifestations between the two groups, providing scientific evidence to optimize dengue prevention strategies and reduce severe cases. Methods Literature related to clinical or infection aspects of dengue fever clinical or infection studies published from database inception to December 31, 2023, were retrieved from CNKI, Wanfang, VIP, and Scopus databases using keyword searches. The literature was screened according to predefined inclusion and exclusion criteria, and a meta-analysis was conducted using R (4.2.3) software. Results A total of 7 148 records were retrieved, ultimately including 30 studies on adults and 12 studies on children, involving eight provinces. The severe dengue comorbidity rate in adults decreased from 6.6% during 1978-1995 to 0.9% during 2014-2023, while in children, it significantly dropped from 15.8% during 1980-1995 to 0.5% during 2014-2019. In adult studies, the primary clinical manifestations and their comorbidity rates were: fever (99.2%), myalgia (55.6%), headache (52.0%), rash (45.5%), and fatigue (34.4%). In pediatric studies, the primary clinical manifestations and their comorbidity rates were: fever (97.6%), headache (38.8%), anorexia (31.9%), rash (30.5%), and lymphadenopathy (20.5%). Conclusions In recent years, the severe dengue comorbidity rates have significantly decreased in both adults and children, indicating that China's dengue prevention and control strategies have achieved remarkable results. The prominent clinical manifestations in adults are associated with organ damage, while children predominantly show gastrointestinal symptoms. Moving forward, efforts should be made to strengthen early diagnosis and standardized treatment to further reduce the clinical impact of dengue fever.

  • Bacterial Resistance under the One Health Concept
    LI Min, JIANG Tianxiang, CHEN Weiye, HU Zengyun, GUO Xiaokui, ZHU Yongzhang
    China Tropical Medicine. 2024, 24(11): 1293-1300. https://doi.org/10.13604/j.cnki.46-1064/r.2024.11.01

    Antimicrobial resistance (AMR), is regarded as one of the top 10 global public health threats. Addressing AMR through the One Health strategy has become a global consensus. AMR monitoring plays a crucial role as the cornerstone of AMR response strategies. This study thoroughly analyzed current situation and progress of AMR monitoring based on the One Health concept in China, the United Kingdom, the United States, and the European Union, and comprehensively compared the similarities and differences of AMR monitoring systems across these countries and regions. The research found that cross-national, cross-regional, and cross-sectoral cooperation in AMR monitoring is increasingly strengthening. However, notable discrepancies still exist among different countries and regions. Notably, most AMR monitoring systems prioritize human and animal health, with relatively insufficient monitoring in the environmental sector. Given the current landscape, China still needs to continue to promote standardized AMR monitoring data sharing and integration across the human, animal, food, and environmental fields, striving to construct a comprehensive and systematic "whole-chain" AMR monitoring system to better tackle this global public health challenge effectively.

  • Special Article
    SU Tianyun, LIU Hongxia
    China Tropical Medicine. 2024, 24(6): 627-636. https://doi.org/10.13604/j.cnki.46-1064/r.2024.06.01

    Mosquitoes and mosquito-borne illnesses remain one of the major public threats which is intensified by the emergence and resurgence of new and existing vector species. Mosquito control is often the only sustainable measure to combat mosquito-borne diseases due to lack or limitation in vaccinations and/or effective medications. Among mosquito control interventions, larviciding to target aquatic habitats is more cost-effective and feasible as opposite to adulticiding which focuses on air-borne adult stages. The available mosquito larvicides are at a historical low owing to numerous reasons. Currently, available larvicides are based on microbial agents, insect growth regulators (IGRs), and a few others of botanical origins. In the IGR arena, juvenile hormone mimics have drawn a lot of attention in research, development, and application. Pyriproxyfen (PPF) was first developed in the early 1970s by Sumitomo Chemical Co. Ltd. (SCC). Its great potential and safety profile to control a wide variety of arthropod pests have been recognized ever since. The current review provides general information and highlights the following advantages of PPF: unique mode of action to mimic the action of natural juvenile hormone (JH) in mosquitoes, broad target spectrum against many mosquito species, the highest bioactivity against mosquitoes as compared with all other known or potential mosquito larvicides, low risk in resistance development and lack of cross-resistance with other larvicides studied, and high activity against species in Stegomyia group. Recently, more potential uses of PPF against adult mosquitoes in bait, barrier treatment, and bed net treatment have been on the horizon. Environmental concerns about PPF residues and their metabolites are also discussed. In general, PPF is one of the critical tools in combating mosquito species of public health importance for now and the foreseeable future.

  • Column on Dengue Fever Prevention and Control
    CHEN Jingjing, MENG Weiwei, JIA Pengben, QIU Li, ZHANG Ling, LUO Yan, XIE Yonghui, JIN Yuming
    China Tropical Medicine. 2024, 24(8): 936-941. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.09

    Objective To provide a scientific basis for improving the prevention and control strategies of dengue fever by analyzing the epidemiological characteristics and influencing factors of reported cases in Hainan Province from 2008 to 2023. Methods Descriptive epidemiological methods were used to analyze the temporal, spatial, and demographic distribution characteristics and influencing factors of reported dengue fever cases in Hainan Province from 2008 to 2023. Spearman correlation analysis was used to explore the correlation between local cases and imported cases. ArcGIS 10.8 and R 4.3.0 were used for graphic production, and SaTScan 10.1.3 software was used for spatiotemporal scanning analysis. Results From 2008 to 2023, a total of 810 cases of dengue fever were reported in Hainan Province, including 164 imported cases and 646 local cases. The 646 local cases reported from June to December, showed a significant seasonal pattern, with September to October being the peak months. The cases were mainly distributed in Haikou City (41.18%) and Ledong County (39.32%). There were two large-scale outbreaks of dengue fever in 2019 and 2023, with 302 and 328 local cases reported respectively (accounting for 97.52% of the total local cases). The male-to-female ratio of local cases was 1.57:1, and cases in the age group of 25 to under 65 accounted for 69.50% of the total. The top three occupations of local cases were housework and unemployment (17.65%), migrant workers (17.34%), and business services (13.78%). From 2008 to 2023, a total of 164 imported cases were reported, with cases reported every month. The peak months were from June to November, accounting for 82.32% of the total imported cases. A total of 66 domestically imported cases were reported, originating from Guangdong Province, Yunnan Province, and Guangxi Zhuang Autonomous Region; 98 cases were overseas imports, mainly from Thailand and Cambodia. The male-to-female ratio of imported cases was 1.65:1, and cases in the age group of 25 to under 55 accounted for 68.29% of the total. The top three occupations of imported cases were business service (33.54%), housework and unemployment (10.37%), and farmers (9.76%). From 2008 to 2013, the years when domestic imported cases were reported in Hainan Province were 2014, 2018, 2019, and 2023, coinciding with the years local cases were reported from 2008 to 2013. There was a positive correlation between local cases and domestic imported cases (r=0.892, P<0.001), while no statistically significant correlation was found with overseas imported cases. Spatiotemporal scanning analysis detected 5 clusters, concentrated in September to October in the years 2019 and 2023. Conclusions Dengue fever is prevalent in Hainan Province, mainly caused by imported cases leading to local outbreaks without forming local epidemics. It exhibits significant seasonal characteristics. Imported cases mainly originate from Cambodia, Thailand, and other Southeast Asian countries, as well as domestically from Guangdong Province, Yunnan Province, and Guangxi Zhuang Autonomous Region. Local cases are mainly distributed in coastal cities and counties.

  • Articles
    HE Qian, CHENG Yi, CHENG Xin, QI Ran, WU Cheng
    China Tropical Medicine. 2024, 24(6): 637-643. https://doi.org/10.13604/j.cnki.46-1064/r.2024.06.02

    Objective To compare the different effects of body mass index (BMI) and lean body mass index (LBMI) on the risk of all-cause death among elderly Chinese individuals. For the more scientific, accurate and convenient measurement of the elderly physique, analysis and evaluation of the health risk factors of the elderly in China. Methods This study is based on follow-up data from 2014 to 2018, involving 5 990 participants who met the inclusion criteria in the Chinese Longitudinal Healthy Longevity Survey. Participants were grouped according to their BMI and LBMI, and both univariate and multivariate Cox proportional hazard models were established to compare the effects of BMI and LBMI on the risk of death in the elderly. According to gender, age, activities of daily living, and comorbidities, subgroup analysis was conducted to study the influence of LBMI in different subgroups. Results The study population predominantly comprised females (52.9%, 3 167/5 990), with an average age of (84.7 ± 10.1) years, and most participants lived in rural areas (55.1%, 3 298/5 990). A majority were non-smokers (82.7%, 4 952/5 990) and non-drinkers (84.3%, 5 050/5 990). The prevalence of hypertension was 32.8% (1 966/ 5 990), diabetes 5.6% (334/5 990), and heart disease 12.9% (774/5 990). In the analysis of the impact of BMI on all-cause death in the elderly, univariate analysis showed that an increase in BMI was associated with a reduced risk of mortality. After adjusted by multiple factors (age, gender, living environment, marital status, average arterial pressure, number of children, smoking, drinking, hypertension, diabetes, heart disease, cerebrovascular disease, tumor, ADL/IADL, number of complications), compared to the normal group, the emaciated group (BMI<18.5 kg/m2) had the highest risk of death (HR=1.15,95%CI: 1.01-1.30); the overweight group (24.0 kg/m2≤BMI<28.0 kg/m2) had a lower risk of death (HR=0.78, 95%CI: 0.67-0.91). In the analysis of the impact of LBMI on the risk of death in the elderly, compared to moderate LBMI, lower LBMI was associated with a higher risk of death. Multivariate analysis showed that compared with moderate LBMI, a decrease in LBMI increased the risk of death, whereas an increase in LBMI did not show statistically significant differences in mortality risk in the elderly. Conclusion In measuring fitness and quality of life in the elderly, LBMI has better representativeness and practical value.

  • Column on Dengue Fever Prevention and Control
    XIE Zhonghang, WU Shenggen, ZHU Hansong, HUANG Wenlong, LIN Jiawei, LI Lingfang, OU Jianming
    China Tropical Medicine. 2024, 24(8): 942-947. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.10

    Objective To analyze the incidence trend and epidemiological characteristics of dengue fever in Fujian Province from 2009 to 2023, identify the high-incidence population and hotspot areas, and a scientific basis for formulating targeted prevention and control measures. Methods The surveillance data of dengue fever during 2009-2023 in Fujian Province were obtained from the National Disease Reporting Information System and analyzed using descriptive epidemiological methods, and the spatial autocorrelation analysis of dengue fever incidence at county/district levels was performed with ArcGlS 10.8. Results A total of 3 586 cases of dengue fever were reported in Fujian Province from 2009 to 2023, with an average annual incidence rate of 0.61/100 000, showing an overall increasing trend year by year (Z=18.35, P<0.001). Among them, there were 2 362 local cases and 1 224 imported cases, with a local/imported ratio of 1.93:1 (2 362/1 224). The local cases were mainly distributed in Fuzhou, Putian, and Nanping, accounting for 87.81% (2 074/2 362). The imported cases were mainly distributed in Quanzhou, Fuzhou, and Xiamen, accounting for 72.55% (888/1 224). The local/imported ratio in Fuzhou, Nanping, and Putian was 6.20:1 (1 557/251), 3.92:1 (145/37), and 3.32:1 (372/112), respectively, all significantly higher than the provincial average level. The spatial distribution of the local cases showed a clustered pattern, with 12 hotspots of incidence, all located in the counties and districts under the jurisdiction of Fuzhou. The onset of the disease had obvious seasonality: imported cases from other countries or regions mainly occurred from July to September (accounting for 45.73%, 519/1 135), imported cases from other provinces mainly occurred from August to November (accounting for 93.25%, 83/89), and local cases mainly occurred from August to October (accounting for 97.50%, 2 303/2 362). The gender ratio for local cases was 0.88:1, and for imported cases, it was 3.04:1. The average age of onset for local cases was 48 years old (Q1=32 years old, Q3=62 years old), while the average age for imported cases was 35 years old (Q1=28 years old, Q3=44 years old). Conclusions From 2009 to 2023, the dengue fever epidemic in Fujian Province showed a continuous upward trend, with spatiotemporal clustering of incidence. Therefore, prevention and control measures should be strengthened in key areas and populations during the high-incidence season.

  • Column on Dengue Fever Prevention and Control
    ZHANG Ye, ZANG Chuanhui, PAN Xiao, GONG Maoqing, LIU Hongmei
    China Tropical Medicine. 2024, 24(8): 914-919. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.05

    Objective Aedes albopictus is the main indigenous vector of dengue fever in China. Understanding the spatial genetic structure of Aedes albopictus populations, migration, and gene flow is crucial for the effective prevention and control of vector-borne diseases. Methods From June to September 2023, mosquitoes were collected and morphologically identified from eight different geographic locations across tropical, subtropical, and temperate zones of China. Genomic DNA was extracted from individual female mosquitoes, and the mitochondrial cytochrome C oxidase I gene was amplified and sequenced. Population genetic diversity and associated population characteristics were assessed using software such as BioEdit, DnaSP version 6, Arlequin 3.5, and Mega 11. Results A total of 233 samples from eight Aedes albopictus populations across the three climatic zones were successfully sequenced, yielding a gene fragment sequence of 632 bp with 19 variable sites and no insertion or deletion mutations. A total of 21 haplotypes were detected, with H4 being the dominant shared haplotype among the three climate types. Haplotype diversity (Hd) ranged from 0.191 (Beijing population) to 0.887 (Xishuangbanna population), and nucleotide diversity (Pi) ranged from 0.000 51 (Beijing population) to 0.002 98 (Xishuangbanna population), suggesting high haplotype diversity and low nucleotide diversity in Aedes albopictus. The genetic differentiation indices ranged from 0.026 to 0.641, with higher genetic differentiation between temperate and tropical/subtropical regions. The analysis of molecular variation supported that genetic differentiation mainly came from within populations (60.45%). Conclusions The ecological and climatic environment in the tropics results in higher genetic diversity of Aedes albopictus. Human activities have exacerbated the risk of dengue transmission across different climatic zones.

  • Natural Epidemic Origin Diseases Research Column
    CAO Yuwen, JIANG Xia, QIAN Zhenyu, ZHANG Haixia, JIA Zhaoyi, LIU Xiaoli
    China Tropical Medicine. 2024, 24(9): 1047-1051. https://doi.org/10.13604/j.cnki.46-1064/r.2024.09.05

    Objective To analyze the epidemiological characteristics of human brucellosis in Hebei Province, and to explore strategies and measures for its prevention and control. Methods Data on brucellosis cases reported in Hebei Province were collected from the National Notifiable Infectious Disease Reporting Information System. The total situation of brucellosis was described, and the epidemiological characteristics of brucellosis in Hebei Province were analyzed. The spatial autocorrelation analysis method was used to explore the spatial distribution characteristics of brucellosis incidence at the county level in Hebei Province. Results From 2018 to 2023, a total of 21 718 cases of brucellosis were reported in Hebei Province, with 1 death (in 2021). The annual incidence rate fluctuated between 3.91/100 000 to 6.26/100 000, with an average annual reported incidence rate of 4.84/100 000. The epidemic peak was from April to July, showing obvious seasonal characteristics. The incidence in males was higher than in females, with a male-to-female ratio of 2.81∶1. The incidence age was concentrated 30-<70 years, accounting for 85.33% of the total cases. The primary occupational group affected was farmers, accounting for 88.59%. The top three cities with the highest average annual incidence rate were Zhangjiakou, Chengde, and Hengshui, which reported a total of 7 801 cases, representing 35.92% of the total cases in the province. From the perspective of spatial distribution: the global spatial autocorrelation analysis showed clustering distribution in Hebei Province from 2018 to 2023, and there were hot spots in local spatial autocorrelation analysis. The high-incidence areas of brucellosis were mainly concentrated in Zhangjiakou (13.651 3/100 000) and Chengde (13.116 7/100 000) in the north of Hebei Province during the past six years. The "low-low" clustering areas were mainly distributed in Tangshan, Shijiazhuang, and Handan. The "low-high" clustering areas were mainly located around the "high-high" cluster areas, in some counties of Zhangjiakou and Chengde. Conclusions The situation of human brucellosis prevention and control in Hebei Province remains challenging. It is recommended to strengthen the management of infection sources, enhance the surveillance of human brucellosis, focus on health education and behavior intervention in high-risk groups, and intensify prevention and control efforts in the hotspot areas.

  • Column on Dengue Fever Prevention and Control Ⅱ
    LI Haiyan, WANG Wei, CHANG Wei, LI Yuanyuan, YAN Xinliu, GAO Yang
    China Tropical Medicine. 2024, 24(10): 1205-1210. https://doi.org/10.13604/j.cnki.46-1064/r.2024.10.9

    Objective To fully understand and analyze the epidemic patterns of dengue fever in Mengla County, Xishuangbanna, and provide a basis for the prevention and control of local outbreaks of dengue fever in Xishuangbanna and other border areas of Yunnan Province. Methods Descriptive epidemiological methods were employed to systematically analyze the temporal, geographical, and demographic distribution characteristics of dengue fever in Mengla County, Xishuangbanna Prefecture, from 2013 to 2023. Results From 2013 to 2023, a total of 3 220 cases of dengue fever were reported, including 2 850 local cases (88.51%) and 370 imported cases (197 cases imported from overseas, 173 cases imported domestically), accounting for 11.49%. Local cases and imported cases were concentrated between July and October, showing seasonal and local characteristics, with a high incidence from August to October, mainly distributed in Mengla Town and Mohan Town. The male-to-female ratio of local cases from 2013 to 2023 was 1.17∶1, and the 20-50 age group accounted for 66.91% of cases. There was a statistically significant difference in the incidence of dengue fever across different age groups for local cases from 2013 to 2023 (χ2=372.711, P<0.05). The top three occupations with the highest number of local cases were farmers 43.79% (1 248/2 850), students 11.19% (319/2 850), and business service workers 7.54% (215/2 850), with the number of imported cases were farmers 126 cases (34.05%), business service workers 61 cases (16.49%), and students 27 cases (7.30%). The number of imported cases peaked in 2023 with 163 cases (44.05% of the total number of imported cases). The Breteau index (BI) from 2013 to 2023 showed an increase in vector density starting in May, with BI between 5-15; a peak in vector density from July to September, with BI between 10-40, and most BI between 20-40; and a gradual decline in October and November, with BI between 5-20. Conclusions The dengue fever outbreak in Mengla County of Xishuangbanna is caused by imported cases, leading to local outbreaks, and exhibiting significant local and seasonal characteristics. The imported cases mainly originated from Southeast Asian countries. Mengla County should remain vigilant, strengthen the monitoring of cross-border transmission, thoroughly implement case surveillance and mosquito prevention and control measures, and adopt timely and effective prevention and control measures at the early stage of the outbreak to prevent large-scale outbreaks and epidemics.

  • Column on Dengue Fever Prevention and Control
    JIN Yan, SUN Dingwei, LUO Huiming
    China Tropical Medicine. 2024, 24(8): 893-895. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.01

    Globally, dengue fever is experiencing a gradual expansion in epidemiological scope, with high infection rates and significant adverse impacts on human health. Dengue fever in China remains predominantly an imported disease and/or a local transmission disease from imported cases, and there is no evidence yet that it has become endemic. Changes in vector distribution, climate changes, and population mobility were reported to correlate with dengue fever epidemic. The most key measure for preventing and controlling dengue fever is to cut off transmission route through comprehensive environmental management, control of mosquito vectors, and elimination of mosquito breeding sites. Dengue fever is an environmental and community disease, and the concept of "One Health" should be adopted, requiring government leadership, multi-sectoral cooperation, and mobilization of the whole society, with everyone participating in the elimination of breeding sites. Prevention and control of dengue fever are feasible, but remain "an uphill battle".

  • Case Report
    LI Xiuxiu, PENG Jieya, ZENG Liling, YAN Haizhen
    China Tropical Medicine. 2024, 24(7): 885-888. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.22

    To report a case of clonorchiasis (Clonorchis sinensis infection) combined with intrahepatic cholangiocarcinoma and review relevant literature to improve the awareness of the clinical physicians regarding Clonorchis Sinensis and provide references for clinical diagnosis and treatment. A retrospective analysis was conducted on a case of clonorchiasis combined with intrahepatic cholangiocarcinoma, admitted to Guangzhou Red Cross Hospital of Jinan University on March 15, 2021, along with a review of related literature. The patient, a 55-year-old male, presented with abdominal distension and poor appetite for over two months and had a history of diabetes and hypertension for many years. He had been consuming raw fish for more than ten years. Upon admission, physical examination revealed a solid mass measuring 8 cm×8 cm was palpable below the xiphoid process in the upper abdomen, with an uneven surface, slightly hard texture, poor mobility, and positive tenderness. Laboratory tests revealed the presence of Clonorchis Sinensis eggs in the stool, and the patient tested positive for Clonorchis Sinensis IgG antibodies. After a comprehensive evaluation that included abdominal ultrasound, abdominal plain CT scan, and contrast-enhanced CT, the patient was diagnosed with "intrahepatic cholangiocarcinoma with multiple intrahepatic metastases." Due to the patient's poor liver function, praziquantel was not administered, and albendazole was instead used at a dose of 10 mg/(kg·d) once daily for seven days. Upon re-admission one month after discharge, no Clonorchis Sinensis eggs were found in the stool. A follow-up after 12 months revealed that the patient had passed away due to liver failure. The serious infection of Clonorchis Sinensis is relatively rare, but it can lead to severe consequences in high-risk individuals, especially when it progresses to intrahepatic cholangiocarcinoma. Clinicians should enhance their awareness of clonorchiasis and promptly identify and provide symptomatic treatment for infections, as early as possible and provide appropriate treatment. Early diagnosis and treatment are crucial for improving the prognosis of patients.

  • Articles
    GAO Lu, CHENG Si, LI Lin
    China Tropical Medicine. 2024, 24(8): 1001-1005. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.20

    Objective To understand the epidemiological and pathogenic characteristics of hand, foot, and mouth disease (HFMD) cluster outbreaks in Tianjin from 2020 to 2023, and to provide a scientific basis for effectively controlling HFMD cluster outbreaks. Methods Epidemic information of Tianjin was collected through the "China Disease Prevention and Control Information System" from 2020 to 2023. Descriptive analysis was used to analyze the time, regional occurrence, and serum typing of HFMD cluster outbreaks. The chi-square test was used to compare the incidence rates in epidemic sites, public and private childcare institutions. The Spearman correlation analysis was performed to explore the correlation between the time interval from onset to reporting and the outbreak scale and duration of the epidemic. Result From 2020 to 2023, 1 111 HFMD clustered outbreaks were reported in Tianjin, with the highest proportion (49.24%) in 2023 and the highest proportion (47.16%) in childcare institutions. A total of 3 175 cases were involved in cluster outbreaks, with an incidence rate of 11.49%. The peak incidence was from September to October, with the incidence rates of cluster outbreaks in childcare institutions, primary schools, and secondary schools being 5.49%, 3.70%, and 2.68%, respectively. There were statistically significant differences in the incidence of cluster outbreaks among various institutions (χ⊃2;=43.498, P<0.001). The duration of the epidemic ranged from 1 to 18 days, with a median of 3 days. The reporting time of the epidemic was positively correlated with the duration of the epidemic (r=0.609, P<0.05) and the number of cases (r=0.515, P<0.05). Coxsackievirus A6 (CV-A6) caused the majority of cluster outbreaks (615 cases, 76.59%), followed by Coxsackievirus A16 (CV-A16) (131 cases, 16.31%). Conclusions HFMD outbreaks in Tianjin predominantly occurred in childcare institutions, with a high incidence of cluster outbreaks during the autumn school opening period. During this period, key places should strengthen morning and afternoon examinations, registration of absences due to illness, and early screening of cluster outbreaks to reduce the scale and duration of the epidemic.

  • Articles
    QIN Qiuzhen, CAI Danzhao, WEN Qilong, LIU Jie, YE Li, LI Xuehua, LIANG Hao, LIU Xin
    China Tropical Medicine. 2024, 24(8): 967-972. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.14

    Objective To investigate the anti-human immunodeficiency virus-1 (HIV-1) activity of Euonymus fortunei extract and its mechanism, providing a theoretical basis for the research and development of traditional Chinese herbal resources in the treatment of acquired immunodeficiency syndrome (AIDS). Methods The peripheral blood mononuclear cells (PBMCs)-HIV-1bal cell model system was used as the experimental model, and the effect of Euonymus fortunei extract on the cell activity and anti-HIV-1 activity of PBMCs was investigated by CellTiter-Glo assay and HIV-1 p24 antigen assay. Additionally, the mechanism of anti-HIV-1 action of Euonymus fortunei extract was determined through the time-of-addition assay and HIV-1 enzymatic assays. Results In the PBMCs-HIV-1bal cell model, Euonymus fortunei extract showed no significant effect on cellular activity at the highest concentration, with a median cytotoxic concentration (CC50)>40 μg/mL. Within the non-cytotoxic concentration range, the level of HIV-1bal decreased with the increase of the extract concentration, with the IC50=0.084 μg/mL, and the SI>476.19. Time-of-addition assay revealed that Euonymus fortunei extract had the highest inhibitory activity on HIV-1IIIB when it was added to cells at the same time as the virus, and the inhibitory rate of HIV-1 activity decreased at 2 h and gradually lost its inhibitory effect on the virus at 18-24 h, similar to the known HIV entry inhibitor Enfuvirtid (T-20). Key HIV-1 enzyme activity experiments found that the extract had no significant inhibitory effect on reverse transcriptase activity but exhibited dose-dependent inhibition of integrase activity, with integrase activity decreasing with increasing extract concentration (IC50=0.18 μg/mL); The extract could inhibit the activity of HIV-1 protease in a certain concentration range (IC50=39.18 μg/mL). Conclusions In this study, it was found that Euonymus fortunei extract has a strong inhibitory activity against HIV-1 activity, which may exert anti-HIV-1 effects by acting on viral entry into cells and inhibiting integrase activity, and has a good application prospect in the research and development of multi-target new drugs against HIV-1.

  • Articles
    LI Lingzhi, XIAO Shan, XU Mingzhong, OU Xinhua, YAO Dong, PEI Ruiqing, HUANG Zheng
    China Tropical Medicine. 2024, 24(6): 680-685. https://doi.org/10.13604/j.cnki.46-1064/r.2024.06.08

    Objective To analyze the genetic evolution and molecular characteristics of the H5N6 avian influenza virus A/Changsha/1/2022(H5N6) in a human infection case in Changsha City, providing insights for the prevention and control of H5N6 avian influenza transmission to humans. Methods The sample underwent whole-genome sequencing on a third-generation sequencing platform. Reference sequences were downloaded from the NCBI and GISAID databases for comparison. The phylogenetic tree was constructed and key amino acid mutation sites were analyzed using MEGA7 software. Results The sequence analysis results revealed that the strain studied belongs to the H5 subtype Clade 2.3.4.4b branch. The PB1 gene shared 99.69% homology with the H5N6 virus A/duck/Hunan/S40199/2021(H5N6) from Hunan Province; PB2 had 98.58% homology with A/Whooper swan/Sanmenxia/Y36/2020(H5N8); and other sequences showed high homology with the strain A/Guangdong/1/2021(H5N6) discovered in Guangzhou in 2021. These results indicate that an infection with a recombinant H5N6 subtype avian influenza virus caused the case. The amino acid composition of the cleavage site was RERRRKR↓GLF, consistent with high-pathogenicity avian influenza characteristics. The HA sequence showed no mutations at the Q226L and G228S sites, indicating the preservation of characteristics binding to avian receptors. However, mutations at the S127P, S137A, T160A, T192R, and A267T sites increased the virus's affinity for humans. A deletion found in positions 59-70 of the NA protein stalk implies enhanced viral virulence in mammals. Mutations were noted in the internal genes; S622G in PB1, K389R and V598T in PB2, N409S in PA, N30D and T215A in M1, and P42S in NS1, which may enhance the virulence of avian influenza virus in infecting mice. Conclusions The H5N6 virus strain detected in a human case in Changsha City in this study is highly pathogenic, prone to bind to avian receptors, but numerous mutations at key amino acid sites facilitate infection in humans. Continuous monitoring and research on H5N6 avian influenza virus should be strengthened

  • Column on Dengue Fever Prevention and Control
    REN Dongsheng
    China Tropical Medicine. 2024, 24(8): 896-900. https://doi.org/10.13604/j.cnki.46-1064/r.2024.08.02

    Dengue fever prevention and control is an urgent need for addressing major infectious diseases in China, and the control strategies need theoretical innovation and technological breakthroughs. Aedes albopictus, the dengue-borne mosquito, exhibits polymorphism in urban environments, resulting in heterogeneous mosquito habitats. This heterogeneity is evident in two aspects: firstly, varying mosquito densities across different habitats, and secondly, differences in vector competence of Aedes albopictus within the same city. The distribution of Aedes albopictus with high vector competence forms discrete "mosquito islands" within the city, analogous to small islands in the sea. Identifying the distribution and scope of these "mosquito islands", combined with vector Aedes daily activity rhythm and innovative ultra-low volume spray technology, can facilitate targeted mosquito control strategies during dengue outbreaks. This approach reduces insecticide spraying, improves mosquito control efficiency, and enables rapid dengue epidemic control.

  • Articles
    FENG Dan, ZENG Yue, LI Yongzhong, YANG Xi, CHEN Shaoming, YE Haimei, HE Changhua
    China Tropical Medicine. 2024, 24(9): 1116-1122. https://doi.org/10.13604/j.cnki.46-1064/r.2024.09.17

    Objective To understand the nitrate pollution status in rural drinking water in Hainan Province, evaluate the health risks to the population, and provide a reference for drinking water hygiene management and intervention measures. Methods Monitoring of nitrates was conducted on 14 037 samples of rural drinking water in Hainan Province from 2012 to 2021, using the environmental health risk model from the "Technical Guidelines for Environmental Health Risk Assessment of Chemical Substances" (WS/T 777—2021) to analyze nitrate content and assess population health risks. Results A total of 14 037 water samples were tested from 2012 to 2021, with a mean nitrate concentration of 0.70 mg/L, and the nitrate compliance rate was 97.08%, and the difference between the annual compliance rates was statistically significant (χ2=97.982, P<0.001). The compliance rates during dry and wet seasons were 97.18% and 96.97% respectively, and the difference was no statistically significant (χ2=0.543, P>0.05). The compliance rates for surface water and groundwater sources were 98.95% and 95.24% respectively, and the difference was statistically significant (χ2=170.898, P<0.001). The compliance rates for finished and tap water were 96.81% and 97.26% respectively, and the difference was no statistically significant (χ2=2.319, P>0.05). The water compliance rates across various cities and counties ranged from 90.41% to 100.00%, and the difference was statistically significant (χ2=332.779, P<0.001). Over the ten years, the average non-carcinogenic risks for different age groups were all less than 1, but the maximum non-carcinogenic risks for some age groups were greater than 1. The average and maximum non-carcinogenic risks for the 1 to less than 2-year-old group were 0.052 and 4.022, respectively. Non-carcinogenic risk increased with age, peaking in the 1 to less than 2-year-old group, and then decreased with further aging. The highest values of nitrate content and maximum non-carcinogenic risks were mainly concentrated in some towns of Haikou, Baisha, Ledong, Danzhou, Lingshui, Dingan, and Changjiang. Specifically, the maximum non-carcinogenic risks of Changhua Town in Changjiang, Xincun Town in Lingshui, Zhongping Town in Qiongzhong, Haiwei Town in Changjiang were 4.022, 3.656, 3.148, 2.998, respectively, indicating long-term exposure non-carcinogenic risk to the population. Conclusions The non-carcinogenic risk of nitrates in rural drinking water in Hainan from 2012 to 2021 is low relatively. However, regions with higher nitrate levels should undertake corresponding intervention measures, such as scaling up pipe network construction, modifying the water treatment process, and controlling pollution sources.

  • Clinical Pathogenic Microorganism Infection and Drug Resistance
    YANG Dan, ZHAO Dongxiao, TAO Jia, HUANG Wenhui, FAN Ruijun, HUI Yanxia, CHEN Ting, ZHANG Yong, JIA Wei, LI Gang
    China Tropical Medicine. 2024, 24(12): 1433-1438. https://doi.org/10.13604/j.cnki.46-1064/r.2024.12.01

    Objective To analyze the antibiotic resistance of clinical isolates from Western China in 2021, providing a reference for guiding the rational use of antibiotics in clinical practices and controlling nosocomial infections. Methods Bacterial samples were collected from nine hospitals in 5 autonomous regions and provinces in Northwest China (690 strains in Ningxia, 141 strains in Gansu, 133 strains in Xinjiang, 179 strains in Qinghai, and 151 strains in Shaanxi) in 2021. MALDI-TOF mass spectrometry was used to confirm bacterial identification, and bacterial susceptibility testing was performed using automated susceptibility testing systems. The results of the susceptibility tests were interpreted according to the 2021 CLSI standards. Results A total of 1 294 clinical strains (non-duplicates) were collected, primarily sourced from sputum specimens 312 strains (24.11%), urine specimens 235 strains (18.16%), pus specimens 147 strains (11.36%), and blood specimens 128 strains (9.89%). Among the 1 294 pathogenic strains, Gram-negative bacteria accounted for 69.47%, whereas Gram-positive bacteria accounted for 30.53%. From the Gram-negative organisms, the most common Enterobacterales strains included E.coli 258 strains (19.94%), K.pneumoniae 166 strains (12.83%), E.cloacae 39 strains (3.01%), and K.oxytoca 36 strains (2.78%). Non-fermentative Gram-negative bacilli constituted 20.63% of all isolates, mainly including P.aeruginosa 129 strains (9.97%) and A.baumannii 87 strains (6.72%). Among Gram-positive bacteria, S.aureus 267 strains (20.63%), E. faecium 68 strains (5.26%), and E.faecalis 48 strains (3.71%) were predominant. Enterobacteriaceae remained highly sensitive to carbapenem antibiotics; however, K.oxytoca had a resistance rate exceeding 15%. P.aeruginosa showed resistance rates of 29.5% and 14% to imipenem and meropenem, respectively; A.baumannii showed resistance rates of 63.2% to both drugs. The detection rate of MRSA was 36.7%, with MRSA showing significantly higher resistance rates than MSSA to most tested drugs. No S.aureus isolates were found resistant to vancomycin, teicoplanin, or linezolid. E.faecium strains demonstrated much higher resistance rates to most of the tested drugs compared to E.faecalis, with a few vancomycin-resistant strains found in both. Conclusions Bacterial resistance to commonly used antibiotics was still severe in Western China. Therefore, medical institutions should continue to enhance the monitoring of bacterial resistance, standardize the management and use of antibiotics, and reduce the transmission and spread of resistant bacteria within hospitals.

  • Articles
    LIANG Xiaoyun, LIANG Changwei, LIANG Xia'nan, PAN Lihua, LAO Xueqiong
    China Tropical Medicine. 2024, 24(7): 857-863. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.17

    Objective To analyze epidemiological characteristics of influenza in Nanning from 2013 to 2022, to provide a reference for the prevention and control of influenza. Methods The data of influenza incidence and etiology surveillance results of the influenza virus in Nanning from 2013 to 2022 were collected to build a database. Data statistical analysis was performed through SPSS 21.0 and Joinpoint software to explore the epidemic trend and epidemic characteristics of the influenza virus in Nanning, and the seasonal index method was used to analyze the epidemic seasons. Results The reported incidence of influenza in Nanning showed an overall upward trend from 2013 to 2022, with an annual percent change (APC) of 47.63% (P<0.05), and an average annual incidence rate of 84.47/105 (ranging from 6.65/105 to 302.55/105). The peak months for influenza in Nanning were January, June, and December, with the seasonal indices of influenza all exceeding 100%, and the proportions of reported cases was 12.69%, 29.41%, and 25.97%, respectively. Both male and female incidence rates showed an upward trend without significant difference (P=0.66). The male-to-female case ratio was 1.24∶1, with the highest case distribution in the 5-<10 years age group, accounting for 31.17%, mainly among students, scattered children, and preschoolers. Xixiangtang District reported the largest influenza cases (21.12%), and Xingning District had the highest annual incidence (214.72/105). Influenza outbreaks mainly occurred in schools and kindergartens, accounting for 97.84%; primary schools accounted for 63.07% of the total. From 2013 to 2022, the dominant strains of influenza viruses alternated in Nanning, with a higher proportion of influenza A (H1N1) and (H3N2) viruses from Jan. 2013 to Mar. 2019. The dominant strains from April 2019 to Dec. 2022 were influenza A (H3N2) and B (Victoria) lineage. Conclusions The intensity of the influenza epidemic in Nanning City showed an increasing trend from 2013 to 2022, with obvious seasonality. The dominant subtypes of influenza viruses varied each year. The main affected groups were students and children, and the outbreaks mainly occurred in schools. Therefore, it is necessary to strengthen the prevention and control of influenza in schools, and the timely detection and handling of outbreaks.

  • Natural Epidemic Origin Diseases Research Column
    GUO Mu, FENG Zhigang, LIU Zhengxiang, WANG Jian, LUO Yan, DONG Yunjun, CAI Wenfeng, DUAN Xingde, PU Ennian, LI Hao, SHAO Zongti
    China Tropical Medicine. 2024, 24(9): 1027-1032. https://doi.org/10.13604/j.cnki.46-1064/r.2024.09.01

    Objective To understand the population composition and quantitative changes of plague hosts and vectors in Menglian County, Yunnan Province, to monitor and investigate the epidemic dynamics of plague, and to evaluate the epidemic risk of plague, providing a scientific basis for plague prevention and control in Yunnan's border areas. Methods Animal plague surveillance was carried out according to the "Yunnan Provincial Plague Surveillance Program", and the data of plague surveillance in Menglian County from 2016 to 2020 were collected and analyzed. In 2020, a plague survey was conducted in two border towns in Menglian County. The samples of host animals and their surface parasitic fleas in residential, agricultural, and forest areas were collected, and serum samples of border residents and plague indicator animals were collected. Yersinia pestis was isolated and cultured from host animal organs and flea samples, and indirect hemagglutination assay (IHA) was used to detect F1 antibody in serum samples. Results A total of 793 host animals, encompassing 11 species across 7 genera and 4 families in 3 orders, were captured in animal plague surveillance in Menglian County, from 2016 to 2020. Rattus tanezumi was identified as the dominant indoor and outdoor species, with composition ratios of 93.58% and 83.91%, respectively. Suncus murinus, Rattus nitidus, Tupaia belangeri, and Rattus andamanensis were common species. The average rodent density indoors and outdoors was 1.33% and 1.65%, respectively. In 2020, the special survey in Menglian County's border areas captured 313 host animals, including 15 species across 9 genera and 4 families in 3 orders. The dominant species were Rattus tanezumi, Rattus andamanensis, and Suncus murinus, with composition ratios of 47.60%, 20.13%, and 10.86%, respectively. The capture rates of indoor and outdoor host animals were 3.25% and 18.81%, respectively. There were statistically significant differences in the capture rates of indoor and outdoor host animals and the density of indoor and outdoor Rattus tanezumi between routine monitoring and special investigation (χ2=30.682,1641.931,32.690,320.415,P<0.001). From 2016 to 2020, the flea infection rate of Xenopsylla cheopis on Rattus tanezumi was 30.97%, with a flea index of 0.79. In the 2020 special survey in Menglian County's border areas, a total of 99 fleas were captured across 7 species, 7 genera, and 4 families, with Xenopsylla cheopis and Palaeopsylla remota as the dominant ectoparasitic flea species, having composition ratios of 69.70% and 20.20%, and an infection rate of 9.90%. The infection rate of Xenopsylla cheopis on the surface of Rattus tanezumi was 12.08% (18/149 ), with a flea index of 0.46. There was a significant difference in the infection rate of Xenopsylla cheopis on the surface of Rattus tanezumi between routine monitoring and special investigation (χ2=22.773, P<0.001). Laboratory test results from both routine monitoring and special investigation were negative. Conclusions The primary species of the main hosts and vectors of plague in Menglian County are prominent, and the density of rodents in the outdoor environment is relatively high. The monitoring and investigation did not find the infection of residents and animals in recent years. However, given the localized low-grade plague endemics in the surrounding areas, it is necessary to continuously strengthen the professional and technical training at the grass-roots level and enhance the monitoring and investigation of plague and other rodent-borne diseases in the border areas to effectively improve the quality and sensitivity of monitoring, timely carry out preventive prevention and control measures, effectively detect the epidemic, and reduce the risk of epidemic.

  • Articles
    ZHANG Kaiyi, LI Haiwen, LI Mingwu, LYU Zhengxuan, LI Xiang, HAN Yi, ZHANG Le
    China Tropical Medicine. 2024, 24(6): 697-701. https://doi.org/10.13604/j.cnki.46-1064/r.2024.06.11

    Objective The aim of this study was to observe the expression levels and clinical significance of peripheral blood interferon γ-inducible protein-10 (IP-10) and various cytokines in patients with different infection statuses of tuberculosis and to assess the efficacy of latent tuberculosis infection (LTBI) in the progression to active tuberculosis (ATB). Methods Seventy-six outpatient and inpatient cases from the Third People's Hospital of Kunming were collected and analyzed from March 2023 to February 2024. The patients were divided into three groups: ATB group (31 cases, 17 males, median age 33 years), LTBI group (27 cases, 17 males, median age 29 years), and healthy control (HC) group (18 cases, 11 males, median age 25 years). Peripheral blood samples from the three groups were taken and the expression levels of IP-10 and cytokines IL-6, IL-4, IL-8, IL-10, IL-12, IL-2, and TNF-α were detected using enzyme-linked immunosorbent assay (ELISA) methods. The t-test was used for normally distributed samples, while the Mann-Whitney U test was used for skewed distributions. For comparisons between multiple groups, the Kruskal-Wallis H test was first employed, followed by Dunn's multiple comparison test for pairwise comparisons. Finally, the effectiveness of each cytokine in distinguishing different population groups was analyzed. Results The expression levels of peripheral blood IP-10 were higher in the LTBI and ATB groups than in the HC group, but the area under the curve (AUC) of the receiver operating characteristic (ROC) of the subjects showed moderate sensitivity (AUC:0.7-0.9) and low specificity (AUC:0.5-0.7). The IL-6 expression levels were in the order of high to low in the ATB group, LTBI group, and HC group, where the HC group was significantly lower than the ATB and LTBI groups (F=12.15, P<0.001). The sensitivity and specificity of the ATB group were higher than those in the HC group. Conclusions IP-10 exhibits unique advantages in distinguishing different tuberculosis statuses. The predictive efficacy of a single cytokine is limited. Combining multiple cytokines such as IL-6 with clinical manifestations, a more accurate and comprehensive prediction model can be established.

  • Bacterial Resistance under the One Health Concept
    ZHAO Ying, DONG Xin, CHEN Jia, DU Qiang, TU Bowen, XU Xiaoguo
    China Tropical Medicine. 2024, 24(11): 1376-1382. https://doi.org/10.13604/j.cnki.46-1064/r.2024.11.13

    Objective To investigate the serotype distribution, antibiotic resistance profiles, and evolutionary relationship of foodborne Salmonella isolates in Changzhou, Jiangsu Province, thereby providing the scientific foundation for the prevention and control of Salmonella related foodborne illnesses. Methods Serotyping, antimicrobial susceptibility testing, and whole-genome sequencing (WGS) were performed on 117 strains of Salmonella isolated from stool specimens of diarrhea patients at the foodborne disease surveillance sentinel hospitals in Changzhou from 2021 to 2023. The Comprehensive Antibiotic Resistance Database (CARD) was used for annotation and analysis of antibiotic resistance genes, and the PubMLST database was used for multilocus sequence typing (MLST). Heatmaps of antibiotic resistance genes were generated using GraphPad Prism 9.5, and phylogenetic trees were constructed using Figtree v1.4.4. Results A total of 21 serotypes of Salmonella were identified from 117 strains of Salmonella, with Salmonella typhimurium and Salmonella enteritidis being the predominant types. The resistance results showed the highest resistance rate to ampicillin (77.78%), followed by tetracycline (58.97%), ampicillin/sulbactam (55.55%), and nalidixic acid (51.28%), with resistance rates exceeding 50%. The most common resistance pattern was CT-AMP-AMS-NAL. Whole-genome sequencing data analysis identified 61 resistance genes, encompassing aminoglycoside, β-lactam, tetracycline, sulfonamide, quinolone, and other resistance determinants. MLST analysis identified 23 sequence types (STs), with ST34 and ST11 being the most prevalent. The phylogenetic analysis revealed high homology among Salmonella strains of the same serotype. Conclusions The dominant serotype of foodborne Salmonella in Changzhou is Salmonella typhimurium, primarily ST34, with strains carrying multiple antibiotic resistance genes, indicating a multidrug-resistant phenotype that warrants attention in future surveillance efforts. The implementation of WGS technology enhances the monitoring of antibiotic resistance trends, providing valuable insights for guiding rational antibiotic use and developing effective prevention and control strategies.

  • Articles
    ZHENG Wu, ZHAO Dingyuan, ZHANG Wei, TANG Heng, FENG Yanmeng
    China Tropical Medicine. 2024, 24(10): 1256-1261. https://doi.org/10.13604/j.cnki.46-1064/r.2024.10.17

    Objective To analyze the timeliness and influencing factors of antiretroviral treatment (ART) among HIV/AIDS patients in Hubei Province from 2017 to 2023. Methods Data were selected from the National AIDS Comprehensive Prevention and Treatment Information System for HIV-infected individuals and AIDS patients residing in Hubei Province from January 1, 2017, to December 31, 2023. Timely treatment was defined as the interval between diagnosis and the initiation of ART being ≤30 days, and non-timely treatment as >30 days. The annual timely treatment rates were calculated, and a time trend regression analysis of these rates was conducted using the Joinpoint regression program 4.9.0.0. The annual percentage change (APC) and average annual change percentage (AAPC) were computed to evaluate the global average change trend across intervals. Cox univariate and multivariate analyses were used to assess the impact of the patient's basic characteristics such as gender, age at diagnosis, ethnicity, education level, infection route, etc. Results Among the 21 332 HIV/AIDS patients, 81.52% were male, and the median age at diagnosis was 43 (28, 56 years). The proportion of patients initiating antiretroviral therapy within 30 days of diagnosis increased from 45.12% in 2017 to 67.61% in 2023, showing an upward trend in the timely treatment rate from 2017 to 2023 (AAPC=6.90). Cox multivariate analysis indicated that females were more likely to initiate treatment in a timely manner after diagnosis (HR=1.15, 95%CI: 1.10-1.21). Compared to cases aged 50 or above, younger age groups had lower treatment timeliness, with HRs (95%CI) of 0.79 (0.76-0.83) for those aged 25 -< 50, 0.67 (0.63-0.72) for those aged 15 -<25, and 0.55 (0.33-0.91) for those aged 0 -<15. Non-Han ethnicities showed lower timeliness in treatment initiation (HR=0.91, 95%CI: 0.83-0.99). Individuals with high school or technical secondary school education, and those with college or higher education, had lower treatment timeliness, with HR (95%CI) of 0.92 (0.88-0.97) and 0.97 (0.92-1.02), respectively. Married or partnered, and divorced or widowed individuals had lower treatment timeliness, with HR (95%CI) of 0.89 (0.86-0.94) and 0.8 (0.76-0.85), respectively. Cases in detention facilities had lower treatment timeliness (HR=0.37, 95%CI: 0.29-0.47). Cases from counseling and testing, and other sources had higher treatment timeliness, with HR (95%CI) of 1.09 (1.04-1.15) and 1.07 (1.00-1.15), respectively. Lower initial CD4+T lymphocyte counts were associated with higher treatment timeliness. Conclusions The timely treatment among HIV-infected individuals and AIDS patients in Hubei Province has improved year by year from 2017 to 2023. Gender, age at diagnosis, education level, marital status, infection route, sample source, and first CD4+T lymphocyte status are all factors that determine the timely treatment of HIV/AIDS.

  • Column on Dengue Fever Prevention and Control Ⅱ
    WANG Liying, LI Weihao, LI Mingfa, MENG Weiwei, YANG Guojing
    China Tropical Medicine. 2024, 24(10): 1186-1193. https://doi.org/10.13604/j.cnki.46-1064/r.2024.10.05

    Objective To analyze the cost-effectiveness of dengue intervention measures and integrated control strategies, to explore the most cost-efficient control strategies and their implementation plans under different scenarios, providing decision-making support and guidance for dengue prevention and control efforts. Methods Based on the dengue transmission dynamics model, a quantitative analysis is conducted on five intervention measures: public education, preventive mosquito control, source reduction, emergency mosquito control, and isolation treatment. A comprehensive dengue control strategy is established, and the particle swarm optimization (PSO) algorithm is employed to search for the optimal parameter values of various control strategies under different scenarios, considering costs—i.e., determining the best implementation plan. The cost-effectiveness ratio (CER) and incremental cost-effectiveness ratio (ICER) indicators are used to evaluate the cost-effectiveness relationships between different control strategies across various scenarios, aiming to explore economically effective dengue control strategies. Results Among the evaluated intervention measures, the cost-effectiveness from lowest to highest is as follows: isolation treatment, public education, source reduction, preventive mosquito control, and emergency mosquito control. For different intervention scenarios, the combination of public education, source reduction, emergency mosquito control, and isolation treatment proved to be the most cost-effective control strategy. When the maximum coverage rate of isolation treatment reaches 70%, implementing the other interventions at approximately 20% coverage or intensity in the second year can eliminate the outbreak within five years. Results Relevant departments should implement preventive control measures in advance, increasing the coverage rate of isolation treatment for dengue fever patients. At the same time, efforts should focus on strengthening public education on dengue fever prevention, formulating scientifically sound and reasonable daily prevention plans, and implementing comprehensive intervention measures while considering costs, aiming to achieve rapid control of the dengue fever epidemic.

  • Column on Dengue Fever Prevention and Control Ⅱ
    HU Minling, ZHANG Xiaoqing, GUO Xiang, LIU Xiaohua, Jone Jama Kpanda Ngobeh, LI Ziyao, ZHAO Lingzhai, CHEN Haiyang, GE Liu, ZENG Shu, REN Wenwen, ZHANG Fuchun, ZHOU Xiaohong
    China Tropical Medicine. 2024, 24(10): 1166-1172. https://doi.org/10.13604/j.cnki.46-1064/r.2024.10.03

    Objective Constructed a nanopore sequencing traceability technology system based on the globally unified DENV-1 genotyping collaborative monitoring strategy and applied it preliminarily to the serum sample testing of patients with dengue fever. Methods Utilizing the DENV-1 whole genome sequences set in the Global Integrated Sequence and Genotyping Database for DENV (GISDD v1.2.1), the specific targeted multiplex PCR primer pairs were screened, designed, and evaluated using MEGA 7.0, Prime-Blast, MPprimer, and GISDDrPrimer softwares. The RNA from the serum samples was extracted and subjected to reverse transcription. The 16 pairs of primers were designed into 2 primer pools for multiplex PCR amplification of the target genome sequences. The library was constructed using magnetic bead purification and the SQK-LSK109 kit according to the operational procedure, followed by MinION sequencing. The sequencing data were analyzed and DENV-1 genomes were assembled for traceability analysis using the GISDD genetic typing platform. Results Sixteen pairs of DENV-1 primers with high coverage to the DENV-1 genomes were designed and identified, establishing a DENV-1 specific multiplex PCR-based nanopore high-throughput sequencing system. It was preliminarily applied to the whole-genome detection of serum samples from 13 patients with dengue fever in Guangzhou. The median of average reads length was 1 668.00 bp, the median of average reads quality was 9.30, the median alignment rate for the reference genome was 97.90%, and the median length aligned to the reference genome NV46 was 1 677.90 bp, with a median genome depth of 12 886.40×. The subsequent genotyping and tracing analyses using GISDD revealed that 9 genomes belonged to DENV-1 clade 1E1, 3 to 1L1, and 1 to 5C1. Conclusions The nanopore sequencing-based DENV-1 whole-genome detection system contextualizing within GISDD described here is characterized by its stability and reliability, enabling the acquisition of high-quality DENV-1 genomes. This approach offers an efficient technical solution for the rapid identification and traceability of DENV genomes during dengue outbreaks, thereby establishing a solid foundation for developing a global collaborative surveillance and control system for dengue.

  • Original article
    GUO Xiaofang, RONG Yihanyu, HUANG Xingyun, LI Xiangyin, CHEN Liyuan, WANG Xuefei, TANG Yerong
    China Tropical Medicine. 2025, 25(2): 141-148. https://doi.org/10.13604/j.cnki.46-1064/r.2025.02.03

    Objective To understand the serotypes and sources of dengue virus (DENV) in Yunnan Province in 2023, providing a scientific basis for dengue fever prevention and control. Methods DENV nucleic acid testing and virus isolation were performed on the serum samples of dengue fever cases diagnosed at three national monitoring sites in Yunnan Province (Longchuan County, Menghai County, Hekou County) in 2023. Dengue virus envelope (E) gene sequencing was performed on positive serum samples and dengue virus isolates, and phylogenetic analysis was conducted using molecular biology software. Results A total of 1 006 dengue fever cases were reported at three monitoring sites in 2023, including 838 imported cases, 161 cases imported from other counties and cities in Yunnan, and 7 autochthonous cases. Among 371 serum samples, 351 were found DENV-positive, including 305 DENV-1 positive samples (174 imported from Myanmar, 1 imported from Laos, 1 imported from Vietnam, 99 imported from Jinghong, 26 imported from Ruili, and 4 local cases), 43 DENV-2 positive samples (8 imported from Myanmar, 6 imported from Jinghong, 26 imported from Ruili, and 3 local cases), 1 DENV-3 positive sample (imported from Myanmar), 1 DENV-4 positive sample (introduced from Ruili), and 1 untyped case. A total of 23 DENV strains were isolated, including 9 strains of DENV-1, 12 strains of DENV-2, 1 strain of DENV-3, and 1 strain of DENV-4. All DENV-1 strains from three monitoring sites belong to genotype I but were located on different evolutionary branches. The DENV-2 strains from Menghai County and Longchuan County belonged to the Cosmopolitan genotype and Asian I genotype, respectively. The DENV-3 strain from Longchuan County belonged to genotype I, and the DENV-4 strain from Longchuan County belonged to genotype I. Conclusions During the dengue fever epidemic season, the border regions of Yunnan Province face dual pressures from both international and domestic imported dengue cases. Imported or introduced cases carried DENVs of serotypes 1-4 (with five genotypes in total), leading to local outbreaks caused by these cases. Imported and local DENVs originated from Southeast Asian countries and exhibited distinct geographic distribution characteristics.

  • Articles
    YANG Haihua, LI Mengxue, LI Yuan, LI Jianjian, ZHANG Mi, DENG Xuemei, WANG Jiali, ZHANG Nian, LIU Jiafa
    China Tropical Medicine. 2024, 24(10): 1251-1255. https://doi.org/10.13604/j.cnki.46-1064/r.2024.10.16

    Objective To analyze the dynamic changes of CD4+T lymphocytes (hereinafter referred to as CD4 cells) in different populations after of HIV infected/AIDS patients antiviral treatment, aiming to understand the characteristics of CD4 cell changes in different populations after antiviral treatment and provide a basis for clinical diagnosis and treatment. Methods A retrospective cohort study was conducted on HIV infected/AIDS patients who received treatment in a hospital in Yunnan Province from 2018 to 2019. According to the inclusion and exclusion criteria, a total of 605 eligible patients were included as research subjects. Analyze the baseline of antiviral therapy and CD4 cell count levels at 6, 12, 18, and 24 months, with the baseline blood collection time of HIV infected/AIDS patients as the starting point and the last follow-up time as the endpoint. Results Among the 605 patients, patients aged ≤30 years had higher CD4 cell levels after antiviral therapy than patients aged >30 years; unmarried patients had higher CD4 cells than married and divorced patients; patients who acquired HIV through homosexual transmission had higher CD4 cell levels than those with heterosexual transmission; patients with mother-to-child transmission had higher CD4 cells at some follow-up points than those with heterosexual transmission and intravenous drug users; patients using regimen groups A, C, and E had higher CD4 cells than those using regimen groups B and D. The CD4 cell count increased rapidly within the first 6 months of ART initiation. Patients with a baseline CD4 cell count of ≤200 cells/μL did not reach normal levels after 2 years of treatment, while patients with a baseline CD4 cell count of >200 cells/μL maintained relatively higher CD4 cell levels throughout ART and reached normal levels after 2 years of treatment. Conclusions The early stage of ART is the rapid growth period of CD4 cells. The earlier the initiation of ART, the quicker the CD4 cell levels recover, leading to better immune function restoration in HIV infected/AIDS patients. Therefore, intensifying monitoring and detection efforts to identify infections earlier can facilitate easier immune function rebuilding, improve treatment effects, reduce the risk of death, and extend patients’ lifespans.

  • Column on Severe Respiratory Infection in Children
    CHEN Huabao, WU Yuhui, YE Xiaoting
    China Tropical Medicine. 2024, 24(7): 772-776. https://doi.org/10.13604/j.cnki.46-1064/r.2024.07.03

    Objective To analyze the changes in the pathogen spectrum of severe lower respiratory tract viral infections in children before and during the outbreak of the COVID-19 pandemic, and to explore the epidemiological characteristics to provide a basis for preventing respiratory viral infections. Methods We conducted a retrospective analysis of clinical data from patients with severe viral pneumonia admitted to the pediatric intensive care unit (PICU) of Shenzhen Children's Hospital from January 2017 to December 2021. Taking the outbreak of the COVID-19 pandemic as the cut-off point, it is separated into the period before the outbreak of the COVID-19 pandemic and the period during the pandemic. Virus spectrum and clinical data between the two groups were analyzed using the chi-square test or Fisher's exact probability method. Results A total of 712 cases of severe viral pneumonia were reported, including 469 males and 243 females, with a median age of 1.25 (0.50, 3.83) years. Among them, 495 cases were under 3 years old, and 626 cases were under 6 years old. The median duration of illness before admission to the PICU was 3.00 (2.00, 5.00) days. Hospital-acquired infections were seen in 6.88% of the children. Firty-four children had been hospitalized ≥2 times due to repeated infections. The detected viruses were influenza viruses (IVA and IVB) in 223 cases (160 IVA and 70 IVB), respiratory syncytial virus (RSV) in 215 cases, human rhinovirus (HRV) in 125 cases, adenovirus (ADV) in 91 cases, human parainfluenza viruses (HPIV) in 53 cases, human bocavirus (HBoV) in 34 cases, cytomegalovirus (CMV) in 26 cases, human metapneumovirus (HMPV) in 17 cases, and human coronavirus (HCoV) in 7 cases. A total of 634 cases were infected with a single virus, while 78 cases were infected with multiple viruses. The top three viruses, sorted by age, were as follows: <1 year: RSV, IVA/B, and HRV; 1-<3 years: IVA/B, RSV, and ADV; 3-<6 years and 6-<10 years: IVA/B, HRV, and ADV; 10-<14 years: HRV, IVA/B, and CMV; sorted by time distribution: March-May and June-August: RSV, IVA/B, and ADV; September-November: RSV, HRV, and IVA/B; December-February: IVA/B, RSV, and HRV. Before the COVID-19 epidemic, the top three viruses were IVA/B, RSV, and ADV, while during the COVID-19 epidemic were HRV, RSV, and HPIV. Conclusions During the COVID-19 pandemic, the viral spectrum of severe lower respiratory tract viral infections in the PICU changed. Before the pandemic, IVA/B, RSV, and ADV were prevalent, while during the pandemic, HRV, RSV, and HPIV were more prevalent. The viral spectrum varies among children of different age groups and in different months.

  • Original article
    ZHANG Sheng, WANG Ziqi, MA Zhifeng, WANG Yinqiu, LI Yuan, HUANG Zhenyu, ZHU Yi, ZHANG Zhen, ZHANG Xindong, CHEN Yixiong
    China Tropical Medicine. 2025, 25(2): 253-258. https://doi.org/10.13604/j.cnki.46-1064/r.2025.02.22

    Objective To conduct an epidemiological investigation and analysis on one imported cholera case in Shenzhen in 2024, providing a reference for cholera prevention and control. Methods A cholera case and 86 close contacts in 2024 were investigated using methods of field epidemiological investigation. Real-time RT-PCR was employed for Vibrio cholerae nucleic acid detection and typing of collected specimens, followed by isolation culture, whole genome sequencing and analysis. Results One severe cholera case was confirmed in an Indian businessman, who recovered and was discharged after rescue and rehabilitation. The pathogen was identified as the toxigenic strain of Vibrio cholerae O1 serotype Ogawa, and genetic evolution analysis showed that it had a very close genetic relationship with Vibrio cholerae isolated from multiple countries such as Bangladesh and Pakistan. Among the 86 close contacts under medical observation, no abnormalities were found. A total of 75 close contact specimens and 38 environment smear specimens from epidemic sites were collected, all testing negative. Conclusion This is an imported cholera epidemic originating from India. The sensitivity of medical institutions to monitoring key infectious diseases such as cholera needs to be improved.