Research based mosquito control in the fight against Buruli ulcer in Australia

Understanding how infectious diseases spread is central to prevention and control, especially when they are carried by vectors.

A vector is an organism that transfers a disease-causing agent from the environment or an infected host to a non-infected one. Vector-borne diseases pose a unique challenge: pinpointing the exact vector species and confirming its role in transmission often requires years of targeted, sophisticated research.

The Puzzle of Buruli Ulcer

For decades, scientists struggled to explain how people in Victoria, Australia, were becoming infected with Mycobacterium ulcerans, the bacterium that causes the devastating Buruli ulcer.

This disease typically begins as a painless lump under the skin, but if untreated it can progress into large ulcers that destroy skin and soft tissue, leaving people with long-term disability. Cases have been rising sharply in recent years, from 135 in 2020 to 344 in 2024.

Additionally, new outbreaks have appeared in areas previously thought to be disease-free. Yet for a very long time, the pathway of transmission remained a mystery.

A Breakthrough in Victoria

Thanks to the Beating Buruli in Victoria initiative, a collaborative partnership supported by the National Health and Medical Research Council Australia, researchers have made major strides in solving this puzzle.

The team’s findings provide strong evidence that mosquitoes play a central role in spreading the bacterium from native possums to humans. This discovery marks a turning point: not only does it explain how the disease moves through communities, but it also opens the door to innovative prevention strategies targeting mosquitoes themselves.

A Large-Scale Trial in Melbourne

Building on this breakthrough, the mosquito experts from the Pest and Environmental Research Group (PEARG) at the University of Melbourne, in collaboration with M. ulcerans experts from the Peter Doherty Institute for Infectious Disease Research, launched a large-scale randomised control trial across metropolitan Melbourne, Australia.

This trial was supported by earlier research on the Australian backyard mosquito (Aedes notoscriptus), which has emerged as a key vector of Buruli ulcer in Victoria.

A population genomic study revealed that this species moves about ten times further than the yellow fever mosquito (Aedes aegypti), making localised mosquito control especially challenging.

Researchers also found that Ae. notoscriptus is highly effective at exploiting cryptic breeding sites, areas around houses that can hold small amounts of water but are not immediately obvious and therefore difficult to manage through traditional source reduction measures alone. Examples include clogged gutters, plant saucers, unmaintained water tanks, trailers, and swimming pools.

Harnessing Mosquito Behaviour for Control

To address these challenges, the trial deployed a new mosquito control system designed to work with the mosquitoes’ natural behaviour to suppress populations even in hidden breeding sites.

Each station uses two active ingredients: a mosquito-specific growth regulator, which prevents larvae from developing into biting adults, and a naturally occurring fungus (Beauveria bassiana), which reduces mosquito biting and ultimately kills adult mosquitoes after a few days.

When a female mosquito enters the control station to lay her eggs, she picks up both agents. As she continues to search for other breeding sites, she spreads the growth regulator, disrupting mosquito development beyond the stations themselves. This “self-dissemination” effect makes the system particularly powerful, reaching sites that are otherwise impossible for humans to treat.

Early Outcomes

The results so far are promising. Mosquito numbers were effectively reduced in areas with stations, and early findings suggest that people living in controlled areas were at lower risk of infection compared to those in untreated areas.

These findings are currently undergoing peer review. While it is too early to draw final conclusions, the approach looks very promising.

This represents one of the first community-wide interventions against Buruli ulcer transmission in a temperate, urban setting, and we hope that the findings and conclusions drawn here in Australia can help guide research and control efforts in other parts of the world where Buruli ulcer remains a challenge.

Next Steps

While reducing mosquito populations is a critical goal, the Beating Buruli in Victoria team also studies how mosquitoes interact with pathogens and is currently exploring questions such as: where and how mosquitoes acquire M. ulcerans, whether they pick it up directly from wildlife, humans, or the environment, and what role breeding, feeding, and mating sites play in transmission.