# Report of two severe cases of Japanese encephalitis virus in travelers returning to France, 2023-2024: clinical, diagnostic, and public health implications

## TL;DR

Two unvaccinated travelers returning to France developed severe Japanese encephalitis virus infections, highlighting the need for vaccination and mosquito bite prevention in endemic regions.

## Contribution

This is the second report detecting Japanese encephalitis virus genome in urine using RT-qPCR.

## Key findings

- Two severe non-fatal Japanese encephalitis virus cases were confirmed in unvaccinated travelers returning to France.
- JEV genome was detected in urine via RT-qPCR, a rare diagnostic finding.
- The cases emphasize the importance of vaccination and mosquito bite prevention in endemic regions.

## Abstract

Japanese encephalitis virus (JEV) is a mosquito-borne pathogen responsible for Japanese encephalitis (JE) clinical cases in Asia and the Western Pacific. Non-JE-vaccinated patients can develop potentially life-threatening neurologic forms.

Here, we present two severe, non-fatal JEV cases in returning travelers from Cambodia (Case 1) and Cambodia and Vietnam (Case 2), imported to France in 2023–2024. Neither patient was vaccinated, and both presented neurologic symptoms requiring hospitalization. Cases were confirmed by RT-qPCR, IgM, and IgG rise and seroneutralization. Interestingly, this is the second report to describe the detection of the JEV genome in urine by RT-qPCR.

This study highlights the critical importance of JE vaccination and the implementation of other personal protective measures to avoid mosquito bites when traveling to a JEV-endemic region.