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Epidemiological characteristics of scrub typhus in Honghe Hani and Yi Autonomous Prefecture, Yunnan Province on China-Vietnam border, 2013-2022
GAO Xiong, DENG Shu-zhen, SU Gui-qin, SHEN Xiu-lian
Abstract55)   HTML    PDF (3256KB)(223)      
Objective To analyze the epidemiological characteristics of scrub typhus in Honghe Hani and Yi Autonomous Prefecture (Honghe Prefecture), Yunnan Province on the border of China and Vietnam, so as to provide a scientific basis for formulating scrub typhus control strategies in the future. Methods The information on cases of scrub typhus in Honghe Prefecture from 2013 to 2022 were collected from the China Information System for Disease Control and Prevention. The data were analyzed using descriptive epidemiological methods, the Chi-squared test, the rank sum test, and concentration distribution analysis. Results A total of 8 035 cases of scrub typhus were reported in Honghe Prefecture in the past 10 years, with an average annual incidence of 17.37/100 000, including 1 death. The reported incidence of scrub typhus showed an increasing trend over the years ( χ 2 trend=3 044.855, P<0.001). Yuanyang County reported the highest number of cases (1 888 cases, an incidence of 47.22/100 000), and Pingbian County reported the highest incidence (1 280 cases, an incidence of 82.53/100 000). The occurrence of scrub typhus had strong seasonality, with the peak period concentrated during June to September (5 854 cases, 72.86%). The cases of scrub typhus were mainly aged 30-<70 years (4 848 cases, 60.33%) and 0-<10 years (1 778 cases, 22.13%). The male-to-female ratio was 0.98:1. A majority of the cases were farmers among occupations (5 588 cases, 69.55%). The median time from disease onset to diagnosis was 10 days. The time from disease onset to diagnosis was statistically different between years ( H=102.812, P=0.001) and between the northern and southern regions (bounded by the Tropic of Cancer) ( H=1 087 686.000, P=0.025), with a shorter time interval in the southern region than in the northern region. The reported cases were mainly from general hospitals at the county (city) level or above, and 95.16% of them were clinically diagnosed cases. Conclusions The incidence of scrub typhus is on the rise in Honghe Prefecture, more frequent in children and middle-aged and elderly people in rural areas, with significant regional difference and significant seasonality with the peak in summer and autumn, and the time interval from onset to diagnosis is relatively long. It is necessary to strengthen scrub typhus surveillance and to reclassify it as a notifiable infectious disease to reduce the economic burden of the disease.
2023, 34 (6): 782-787.   doi: 10.11853/j.issn.1003.8280.2023.06.014
Distribution characteristics of mosquito and their natural infection with Japanese encephalitis virus in Yunnan province
DENG Shu-Zhen, ZHANG Hai-Lin, LI Jin-Mei
Abstract1503)      PDF (396KB)(1056)      

【Abstract】 Objective To analyze the distribution characteristics of mosquito in Yunnan province and its relationship with the arborvirus such as Japanese encephalitis (JE), and provide the scientific basis for its prevention and control. Methods Mosquitoes were collected from the residential areas and the stables of livestocks in villages at night, and bamboo forests in the day. Results A total of 158 909 adult female mosquitoes were collected, which belonged to 88 species 10 Genera, and were mainly Culex,Anopheles and Aedes, accounting for 56.66%, 25.35% and 13.88% respectively. Among them, as many as 132 081 adult mosquitoes belonging to 63 species 7 Genera were caught in the residential areas at night, in which Cx.triaeniorhynchus has the highest proportion (42.12%), followed by An.sinensis (23.31%). And 26 828 adult mosquitoes belonging to 48 species 5 Genera were caught in the field by day, and the proportion of Ae.albopictu was highest (31.89%), followed by Ae.annandalei(20.21%). A total of 131 538 female mosquitoes that belonged to 29 species of 8 Genera were divided into 3957 groups. As a result, 81 strains of JE virus were isolated from mosquitoes (17 species 5 Genera). The virus strains isolated from Culex were the most(59 strains)accounting for 72.84%, followed by Anopheles (8 strains ) accounting for 9.88%, and Aedes (9 strains) accounting for 11.11%. Only two  strains  were  isolated  from  Armigeres  and  Mansonia,  accounting   for  2.47%.  About  27  strains  JE  were  isolated  from Cx.triaeniorhynchus, accounting  for   33.33%  of  the  total.  Conclusion The  dominant  species  in  the  residential areas  are  Cx.triaeniorhynchus, An. sinensis,  Cx.fuscocephalus, Cx.whitmorei, Cx.pseudovishnui and An.vagus  at  night,  while  Ae.albopictus,  Ae.pseudalbopict,  Ae.annandalei,  Ae.vexans  and  Ar.subalbatus  were   the  dominant  species  in  the  field  by  daytime. Cx.triaeniorhynchus  and  Ae.albopictus are the main vectors of JE and Dengue fever in Yunnan province, respectively.

2009, 20 (4): 344-348.