中缅部分边境地区登革热流行情况调查

Investigation of the epidemiological characteristics of dengue fever in the China-Myanmar border area

目的了解中缅边境地区云南省盈江那邦镇和缅甸拉咱市登革热流行状况,为边境地区登革热防控提供科学依据。方法 2017年9-10月,在中缅边境地区中国云南盈江那邦镇和缅甸拉咱市各选3个调查点,采用背负式电动捕蚊器采集成蚊并用形态学方法鉴定蚊虫种类,捕获的蚊虫标本通过接种C6/36细胞分离病毒;采用间接酶联免疫吸附试验(ELISA)检测健康人群血清登革病毒IgG抗体;采用NS1抗原检测试剂检测疑似DF病例血清标本,阳性标本采用RT-PCR方法检测鉴定登革病毒血清型。结果共捕获6属14种703只蚊虫,其中登革热媒介埃及伊蚊为当地优势蚊种(57.75%,406/703),未发现埃及伊蚊携带登革病毒。采集的256份健康人血清中DENV IgG抗体阳性13份(5.08%,13/256),其中盈江那邦DENV IgG阳性率4.17%(4/96),缅甸拉咱5.63%(9/160),差异无统计学意义(χ^(2) =0.265,P>0.05);488份疑似登革热病人血清DENV阳性166份(34.02%,166/488),其中盈江那邦阳性83份(32.0%,83/259),缅甸拉咱阳性83份(36.24%,83/229)。从10份阳性标本中分离出5株DENV病毒,其中4株DENV-1(盈江那邦3株,缅甸拉咱1株),1株DENV-3(盈江那邦)。结论中缅边境地区盈江那邦镇和缅甸拉咱市登革热媒介埃及伊蚊分布广,DENV血清型主要以DENV-1为主,应加强中缅边境地区登革热疑似病例和媒介的监测。

Objective To investigate the prevalence of dengue fever in the town of Nabang, Yingjiang County, Yunnan Province and the City of Laiza, Myanmar in order to provide local evidence for formulating measures to prevent and control significant mosquito-borne diseases in the China-Myanmar border area. Methods A total of 6 field sites were selected in the China-Myanmar border area, with 3 in the town of Nabang, Yunnan, China and 3 in the City of Laiza, Myanmar. Adult mosquitoes were collected by backpack aspirators in the daytime from Sep. to Oct. 2017, and all collected mosquitoes were identified morphologically. Viruses were isolated from Aedes aegypti via C6/36 cell inoculation. Venous blood(3-5 ml) was collected from healthy residents at the field sites, the serum was centrifuged, and dengue virus IgG antibodies were detected using ELISA. Venous blood(3-5 ml) was collected from patients suspected of having dengue fever at hospitals at the field sites, and the NS1 antigen of the dengue virus were detected using immunochromatography. RT-PCR was used to identify positive samples for virus isolation and sequencing. Results A total of 703 mosquitoes from 14 species in 6 genera were collected. Dengue vector Ae. aegypti was the dominant species locally(57.75%, 406/703) though it did not carry the dengue virus. A total of 256 serum samples were collected from healthy individuals. Of those, 13(5.08%, 13/256) tested positive for DENV IgG antibodies. Of the samples from Nabang, 4.17%(4/96) tested positive for DENV IgG antibodies. Of the samples from Laiza, Myanmar, 5.63%(9/160) tested positive for DENV IgG antibodies. Positivity for DENV IgG antibodies did not differ significantly among the three groups(χ^(2) =0.265, P>0.05). A total of 488 serum samples were collected from patients suspected of having dengue fever. Of those, 166 tested positive for DENV antibodies(34.02%, 166/488), including 83 samples(32.0%, 83/259) from Nabang and 83 samples(36.24%, 83/229) from Laiza, Myanmar. Five strains of DENV were isolated from 10 positive samples;four strains(80%, 4/5) were identified as DENV-1 and one strain(20%, 1/5) was identified as DENV-3. Conclusion Ae. aegypti was widely distributed in the China-Myanmar border area, and the risk of dengue fever was high. DENV-1 was the primary serotype of DENV, and the current findings suggest that the relevant departments should enhance their surveillance of dengue fever cases and vectors.