Molecular Epidemiology and Genetic Diversity of Zika Virus from Field-Caught Mosquitoes in Various Regions of Thailand

Zika virus (ZIKV) infection is an emerging and re-emerging arbovirus disease that is transmitted to humans through the bite of infected mosquitoes. ZIKV infections were first described in Thailand in 1954 from the sera of indigenous residents and several travelers returning from Thailand in 2014. However, reported cases in Thailand have been increasing since 2015 and 2016, and epidemiological information about the vectors of ZIKV is unclear. We investigated the molecular epidemiology and genetic diversity of ZIKV from mosquitoes collected from different geographic regions experiencing ZIKV outbreaks in Thailand. Polymerase chain reaction was used to amplify the non-structural protein (NS5) gene of ZIKV, which was then sequenced. A total of 1026 mosquito samples (626 females, 367 males, and 33 larvae) were collected from active ZIKV patients’ houses. ZIKV was detected in 79 samples (7.7%), including Aedes aegypti (2.24% female, 1.27% male, and 0.19% larvae), Culex quinquefasciatus (1.85% female, 1.66% male, and 0.29% larvae), and Armigeres subalbatus (0.1% female and 0.1% male), whereas no ZIKV was detected in Aedes albopictus. Phylogenetic analysis of the 79 positive samples were classified into two clades: Those closely related to a previous report in Thailand, and those related to ZIKV found in the Americas. This is the first report of the detection of ZIKV in Ae. aegypti, Cx. quinquefasciatus, and Ar. subalbatus mosquitoes, and genetic variations of ZIKV in the mosquitoes collected from several geographic regions of Thailand were examined. Detection of ZIKV in male and larval mosquitoes suggests that vertical transmission of ZIKV occurred in these mosquito species. This study provides a more in-depth understanding of the patterns and epidemiologic data of ZIKV in Thailand; the data could be used for future development of more effective prevention and control strategies of ZIKV in Thailand