# Interepidemic xenosurveillance of Japanese encephalitis virus and Zika virus in Culex mosquitoes from Ubon Ratchathani province, Thailand

## TL;DR

This study looked for Japanese encephalitis and Zika viruses in Culex mosquitoes in Thailand but found no evidence of either virus, suggesting possible low circulation or unsuitability of the mosquitoes as vectors.

## Contribution

The study contributes new xenosurveillance data on JEV and ZIKV in Culex mosquitoes from Ubon Ratchathani province, Thailand.

## Key findings

- No JEV or ZIKV was detected in 5,587 Culex mosquitoes collected from two districts.
- The absence of the viruses may indicate low viral circulation or unsuitability of Culex mosquitoes as vectors in the region.
- Further xenosurveillance is recommended to prepare for potential future outbreaks.

## Abstract

Some Culex mosquitoes are competent vectors for Japanese encephalitis virus (JEV) and Zika virus (ZIKV), which cause public health problems worldwide, especially in South-east Asia. Xenosurveillance of Culex mosquitoes remains limited compared with other common mosquito-borne diseases. This study aimed to identify JEV and ZIKV in field-caught Culex mosquitoes collected from Ubon Ratchathani province.

We investigated the presence of JEV and ZIKV in Culex mosquitoes from two districts in Ubon Ratchathani province, Thailand, and examined their role in viral interepidemic circulation. Female Culex mosquitoes (5,587) were collected using a mechanical aspirator from indoors and outdoors. The consensus sequences of the E and NS1 genes of JEV and the E gene of ZIKV were identified using real-time reverse transcription-polymerase chain reaction.

From 335 sample pools that contain a total of 5587 adult female Culex mosquitoes collected from Don Yung, Mueang district (4,406) and Phon Duan, Det Udom district (1,181), none of the collected mosquitoes tested positive for either JEV or ZIKV.

This study did not find JEV and ZIKV in Culex mosquitoes collected from the area of collection, which may be due to the low circulating amount of the virus in the vectors in the area, making it undetectable, or it may be because Culex mosquitoes are not suitable vector for the virus being tested. However, further xenosurveillance study of JEV and ZIKV in mosquito is suggested to prepare for the next outbreak.