# Locally Acquired Dengue in Townsville, Australia, 2024–2025: An Outbreak Report in a Non-Endemic Region with wMel Wolbachia-Infected Aedes aegypti

## TL;DR

Townsville, Australia, experienced a dengue outbreak in 2024–2025 despite using Wolbachia-infected mosquitoes to control the virus.

## Contribution

This report highlights the vulnerability of Wolbachia-covered regions to dengue outbreaks and the need for continued monitoring.

## Key findings

- Sixteen dengue cases occurred in 2024/2025, the second local outbreak since 2014.
- Higher-than-average rainfall was associated with the outbreak in two inner-city suburbs.
- Wolbachia-infected mosquitoes may not fully prevent dengue transmission despite high coverage.

## Abstract

During the 2024/2025 wet season, Townsville had its first sustained autochthonous outbreak of dengue disease caused by dengue virus type 2 (DENV-2), the second locally transmitted outbreak of dengue since 2014 following the introduction of wMel strain Wolbachia-infected mosquitoes, a control strategy for dengue virus (DENV) and other Aedes-transmitted arboviruses. In comparison to two recorded locally acquired cases of dengue in 2020, the 2024/2025 outbreak resulted in sixteen cases in two inner-city suburbs of Townsville during the wet season associated with higher-than-average rainfall. This second dengue outbreak since 2014 highlights that Townsville and other north Queensland communities where Wolbachia mosquito programs have been deployed remain vulnerable to DENV incursions and local disease outbreaks despite the apparent high coverage of Wolbachia-infected mosquitoes. Whilst these control strategies have likely contributed to a reduction in the number and frequency of autochthonous DENV outbreaks in north Queensland, ongoing maintenance and monitoring of Wolbachia-infected mosquito coverage is necessary, together with timely review and improvement in dengue awareness and prevention health promotion activities in the community.