Mosquito autodissemination stations cut Buruli ulcer risk by 83% in Melbourne trial
核心洞察
A randomised controlled trial across 12 Melbourne areas found autodissemination stations reduced Aedes notoscriptus (搜索) mosquito egg counts by roughly 70% over eight weeks.
The intervention was associated with an 83% lower incidence of Buruli ulcer (搜索) among nearby residents during the predicted peak effect period (IRR 0.167, 95% CI 0.026–1.054, P = 0.047).
Researchers used genomic epidemiology and incubation-period modelling to attribute locally acquired Mycobacterium ulcerans (搜索) infections, overcoming the disease's ~138-day incubation period.
A Melbourne-led randomised controlled trial has demonstrated for the first time that suppressing mosquito populations directly reduces a person's risk of contracting Buruli ulcer (搜索), a serious skin and soft-tissue infection caused by Mycobacterium ulcerans (搜索). Published in Nature Microbiology, the study found that targeted mosquito control using autodissemination stations cut the incidence of Buruli ulcer by over 80 per cent among people living in treated areas.
The trial, conducted by University of Melbourne researchers from the Peter Doherty Institute (搜索) for Infection and Immunity (Doherty Institute), was carried out across 12 areas in Melbourne's inner north-west, including Brunswick West, Essendon and Moonee Ponds. Six areas received specialised mosquito control traps, known as autodissemination stations, while six matched areas served as controls.
How the intervention works
The In2Care mosquito station consists of a reservoir holding 3.5–4.5 litres of water with yeast tablets to attract gravid mosquitoes. A floating platform equipped with a statically charged gauze strip coated with a powder containing pyriproxyfen (搜索) (74%) and Beauveria bassiana (搜索) (10%) provides a resting place for adult mosquitoes. When mosquitoes land on the gauze, the bioactives transfer to them; after depositing eggs, the mosquitoes leave and disseminate pyriproxyfen to other breeding sources.
Pyriproxyfen (搜索) inhibits the metamorphosis of mosquito pupae into adults, preventing adult emergence, while B. bassiana causes mortality within 8–10 days. The stations target Aedes notoscriptus (搜索), a common Australian backyard mosquito that breeds in small, hidden sources of water around homes.
"After eight weeks, we found that mosquito egg counts had dropped by around 70 per cent across areas with the control stations," said Dr Véronique Paris, Medical Entomologist at the Doherty Institute (搜索) and co-first author of the paper.
Trial design and mosquito reduction
The study selected a 50 km² area across inner northwestern suburbs of Melbourne with active Buruli ulcer (搜索) transmission based on 2023 human case data. Twelve areas were matched, and a random number generator assigned six treatment and six control areas, each comprising roughly 80 residential houses. Approximately 100 In2Care stations were deployed in each treatment area over an eight-week period from 25 January 2024 to 21 March 2024.
Mosquito populations were evaluated using egg counts from 480 ovitraps distributed across the study area. Before the intervention, roughly 80% of ovitraps across all sampling areas were positive, with no significant difference between treatment and control areas. After the intervention, the proportion of positive ovitraps in treatment areas significantly decreased to 33.4% (z = 18.588, P < 0.001), compared with 52.7% in control areas. The difference between control and treatment areas after the intervention was highly significant (z = 7.844, P < 0.001).
A synthetic control analysis confirmed a 70.3% decrease in average egg numbers across all treatment areas compared with all control areas in the three weeks after intervention. In mosquito breeding hotspots, mean egg counts declined by 96.9% in treatment areas versus 93.0% in control areas, with the magnitude of decline significantly greater in treatment areas (Welch's t-test, t = −3.25, d.f. = 12.17, P = 0.007).
Linking mosquito reduction to human disease
Assessing the impact on human Buruli ulcer (搜索) cases posed a significant challenge because of the disease's long incubation period—a mean of 138 days with an interquartile range (IQR) of 101–171 days. "Because symptoms typically appear around five months after infection, we had to work backwards to estimate when infection happened and use forensic genomic analysis to determine which cases were acquired locally," said Dr Andrew Buultjens, Senior Research Fellow at the Doherty Institute (搜索) and co-first author.
The researchers used M. ulcerans genome sequence data from bacterial isolates cultured from patients to confirm that cases were acquired in the study area, referencing the core genome phylogeny to attribute infections to the specific Melbourne genotype. They reconstructed probable exposure dates by sampling incubation times from empirical distributions and subtracting them from known symptom-onset dates across 200 Monte Carlo iterations.
Using a Poisson likelihood ratio test at the predicted peak impact of the In2Care stations (week 8 of deployment, 21 March 2024), the team observed an incidence rate ratio (IRR) of 0.167 (95% CI 0.026–1.054, P = 0.047)—an 83% reduction in incidence in treatment zones relative to control zones. Comparisons for the same date in 2023 and 2025, when no interventions were run, showed no significant difference in IRR.
"By intersecting timing and location of infections, we found that when we reduced mosquito numbers by 70 per cent over an eight-week period, there was an 83 per cent lower incidence of Buruli ulcer (搜索) among people living nearby," Dr Buultjens said.
A sliding-window analysis further supported the finding. The difference in cases between treatment and control zones tracked the reduction in mosquito egg counts across all exposure windows, following a positive linear trend (R² = 0.85). An inverse sliding-window profile between control and treatment zones was observed only in 2024, not in the same date range in 2023 or 2025.
Public health significance
Professor Tim Stinear, Director of the WHO Collaborating Centre for Mycobacterium ulcerans (搜索) at the Doherty Institute (搜索), said the findings have for the first time unlocked a feasible way to prevent Buruli ulcer (搜索) across an urban area.
"While we knew mosquitoes played an important role in spreading Mycobacterium ulcerans (搜索), this study shows for the first time that reducing mosquito populations can reduce the risk of disease in people," Professor Stinear said. "These findings provide evidence for public health control strategies to help communities affected by Buruli ulcer (搜索)."
Dr Finn Romanes, Director of the Western Public Health Unit in Victoria, recognised the significance of the findings. "There is now an opportunity to apply this research to find ways to respond at scale to reduce mosquito populations in areas where they contribute to Buruli ulcer (搜索) infection," Dr Romanes said.
Professor Ary Hoffmann from the School of BioSciences and Bio21 Institute highlighted the broader implications of mosquito-borne disease transmission. "As climate change leads to extreme rainfall and warmer temperatures that favour mosquito breeding, we are likely to see an increase in transmission of a variety of mosquito-borne diseases like Buruli," Professor Hoffmann said. "We need to focus on reducing mosquito breeding sites and adopting new technologies like the autodissemination approach used here to facilitate this outcome."
The study is part of Beating Buruli in Victoria, a collaborative research initiative funded by the National Health and Medical Research Council of Australia (NHMRC) and the Victorian State Government, with additional support from the Wellcome Trust. The project is led by the WHO Collaborating Centre for Mycobacterium ulcerans (搜索) at the Doherty Institute (搜索), with partners including Western Public Health Unit, Agriculture Victoria, Austin Health, the Victorian Department of Health, CSIRO, and other organisations.