Department of Community Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
Environmental and Occupational Medicine Excellence Center, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
J Travel Med. 2024 Mar 1;31(2). doi: 10.1093/jtm/taae022.
Travel to Southeast Asia increases the likelihood of acquiring mosquito-borne Flavivirus infections such as dengue (DENV), Japanese encephalitis (JEV) and Zika viruses (ZIKV). Expatriates are long-term travellers who have a higher risk of mosquito-borne illness at their destination country. The purpose of this study was to evaluate the seroprevalence of DENV, JEV and ZIKV infections and the determinants contributing to seropositivity among expatriates living in Thailand.
A cross-sectional study was performed from December 2017 to February 2020. Expatriates from non-Flavivirus endemic countries were recruited. 5 mL of blood was collected for DENV 1-4, JEV and ZIKV antibody testing by plaque reduction neutralization test (PRNT50). Individuals with vaccination histories or diagnoses for dengue, Japanese encephalitis, yellow fever and tick-borne encephalitis were excluded.
Among 254 participants, most participants (83.1%) were male, the mean age was 65 years and the median duration of stay in Thailand was 6 years. Seroprevalence rate of any Flavivirus, non-specific DENV, DENV1-4, JEV and ZIKV were 34.3, 30.7, 20.5, 18.1, 18.9, 10.6, 4.7 and 2.8%, respectively. The presence of neutralizing antibodies against DENV1-4 positively correlates with the duration of stay in Thailand. DENV seropositivity was associated with living in urban areas (aOR 2.75, 95% CI 1.36-5.57). Expatriates were unlikely to have detectable anti-JEV antibodies regardless of time spent in a JEV-endemic area. No risk factors were identified that were significantly associated with JEV or ZIKV seropositivity. Only 48.4% received pre-travel counselling services, while only 18.9% visited a travel medicine specialist.
A high proportion (34.3%) of long-term expatriates living in Thailand were seropositive for flavivirus, mainly from dengue (30.7%). To minimize risk, travel medicine practitioners should provide adequate pre-travel health risk information on mosquito-borne flavivirus infection and offer advice on mosquito bite prevention strategies. Dengue vaccine might be considered in high-risk travellers such as long-term expatriate.
前往东南亚旅行会增加感染蚊媒 Flavivirus 感染的可能性，例如登革热（DENV）、日本脑炎（JEV）和 Zika 病毒（ZIKV）。侨民是长期旅行者，他们在目的地国家感染蚊媒疾病的风险更高。本研究的目的是评估居住在泰国的侨民中 DENV、JEV 和 ZIKV 感染的血清流行率以及导致血清阳性的决定因素。
本研究是一项横断面研究，于 2017 年 12 月至 2020 年 2 月进行。招募了来自非 Flavivirus 流行国家的侨民。采集 5mL 血液，通过蚀斑减少中和试验（PRNT50）检测 DENV 1-4、JEV 和 ZIKV 抗体。排除有登革热、日本脑炎、黄热病和蜱传脑炎疫苗接种史或诊断史的个体。
在 254 名参与者中，大多数参与者（83.1%）为男性，平均年龄为 65 岁，在泰国的居住时间中位数为 6 年。任何 Flavivirus、非特异性 DENV、DENV1-4、JEV 和 ZIKV 的血清流行率分别为 34.3%、30.7%、20.5%、18.1%、18.9%、10.6%、4.7%和 2.8%。DENV1-4 的中和抗体存在与在泰国的居住时间呈正相关。DENV 血清阳性与居住在城市地区有关（aOR 2.75，95%CI 1.36-5.57）。无论在 JEV 流行地区的居住时间如何，侨民都不太可能检测到抗 JEV 抗体。未发现与 JEV 或 ZIKV 血清阳性显著相关的危险因素。只有 48.4%的人接受过旅行前咨询服务，只有 18.9%的人咨询过旅行医学专家。
居住在泰国的长期侨民中有相当高比例（34.3%）的人对 flavivirus 呈血清阳性，主要来自登革热（30.7%）。为了降低风险，旅行医学从业者应提供有关蚊媒 flavivirus 感染的充分旅行前健康风险信息，并就蚊虫叮咬预防策略提供建议。对于长期侨民等高风险旅行者，可以考虑接种登革热疫苗。
