of mosquito-borne disease across Australia
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In 2024, public health teams mobilised on Mer Island in the Torres Strait to contain dengue.
Eight locally acquired cases had emerged, the first outbreak detected there since 2017.
Responders combined active case finding, health promotion and vector control, which targets disease-carrying mosquitoes.[6]
A new Monash University review places that outbreak inside a wider global pattern of climate-driven disease risk.
Dr Toby Cumming, a research fellow at the Monash School of Public Health and Preventive Medicine, led the work.
The review examines how climate and other forces shape malaria and dengue risk.[1]
Cumming says rising temperatures and altered rainfall expand areas where Anopheles and Aedes populations can thrive.
Anopheles mosquitoes spread malaria, a parasitic disease, while Aedes mosquitoes spread dengue, a viral illness.
Local variability and seasonal effects complicate the picture, yet the impacts on both diseases look broadly similar.[1]
CSIRO ranks mosquito-borne illness as the most climate-sensitive type of communicable disease in Australia. Its 2024 discussion paper expects warming, rainfall and flooding changes to aid transmission. The national science agency treats the threat as a planning priority rather than a distant possibility.[3]
CSIRO identifies three mechanisms. Pathogens mature faster inside the mosquito, which shortens the incubation period before a bite can transmit infection. Suitable habitat spreads to new regions, and mosquito survival and breeding seasons lengthen.[3]
Dengue-affected areas keep growing as temperatures rise across the world. Transmission now reaches higher altitudes and temperate regions with little historical experience of the disease. Australian health planners face a map that shifts with every warm season.[2]
Southern Australia sits outside the malaria risk zone, yet dengue already affects warmer areas such as far north Queensland. Anders, an associate professor at Monash, warns that outbreaks could spread further south as temperatures rise. Far north Queensland therefore offers an early indicator for the rest of the country.[2]
Places without a long history of dengue are increasingly recording local outbreaks. Anders points to southern Europe and the southern United States. She says Australia needs to stay highly aware of that trend, because local outbreaks can follow.[2]
A peer-reviewed study modelled the range of Aedes aegypti, the main dengue vector. It tested today's climate alongside projected warming scenarios for 2030 and 2050. Researchers then compared the results with transmission limits drawn from historical Australian epidemics.[4]
South-east Australia has dried, and communities face escalating water restrictions. The study concludes that a proliferation of domestic water storage tanks could expand the mosquito's range. That would create dengue risk in most major cities during their warm summer months.[4]
Dengue rates are rising globally. Malaria has declined in general, despite more favourable climate conditions. Anders says better drugs and risk-reduction campaigns could explain the gap.[2]
Cumming credits mosquito control and drug therapies with major gains against malaria. The malaria record shows that climate suitability alone fails to predict disease burden. Sustained public health investment can outweigh a climate that favours the mosquito, at least for one disease.[1]
Rapid urbanisation offers a second explanation for the divergence between the two diseases. Aedes mosquitoes, which carry dengue, suit urban environments, while malaria is more typically a rural disease. Tropical cities keep growing, which favours the mosquito that carries dengue.[2]
Anders says a new vaccine and Wolbachia-based control offer a chance to curb dengue. Wolbachia, a bacterium that cuts mosquitoes' ability to transmit viruses, now operates in Cairns, Townsville and other northern Queensland centres. Anders calls it largely responsible for cutting northern Queensland outbreaks to almost zero over a decade.[2]
Japanese encephalitis virus, a mosquito-borne flavivirus, circulated in tropical north Queensland between 1995 and 2005. Until 2022, the disease's southern limit sat in far north Australia. Badu Island, in the Torres Strait, recorded three cases and two deaths in 1995.[5]
In 2022 the virus spread across the southern states, causing 30 confirmed human cases and six deaths. La Niña, a Pacific Ocean climate pattern, delivered extraordinary rainfall in 2021 and 2022. An estimated 740,546 Australians live within the dispersal range of mosquitoes from infected piggeries.[5]
Authorities declared the outbreak a communicable disease incident of national significance on 4 March 2022. By mid-July, more than 70 piggeries across four states carried the virus. Heavier rainfall had drawn migratory water birds further south and increased mosquito breeding.[7]
Researchers at QIMR Berghofer, a Brisbane medical research institute, feared the virus had become endemic, meaning permanently established. Clinicians could only manage symptoms, because infection has no specific treatment. Two effective vaccines existed in 2022, yet limited supplies forced authorities to prioritise high-risk groups.[8]
The Mer Island outbreak affected a Torres Strait Islander community off the northern tip of Queensland. Authors from the Torres and Cape Public Health Unit documented the response. They stress the importance of testing in primary healthcare, vector control and ongoing surveillance to limit local transmission.[6]
CSIRO proposes criteria for assessing future communicable disease risk across Australia. The criteria include disease severity and the disproportionate burden on Aboriginal and Torres Strait Islander peoples. Those criteria place First Nations health inside national risk planning.[3]
A February 2025 Medical Journal of Australia editorial reviewed Australia's Japanese encephalitis surveillance efforts to date. It urged authorities to shift from a reactive surveillance and response approach. Australia had launched its first National Health and Climate Strategy in 2023.[9]
Cumming says the research reinforces the need for a coordinated approach. That approach spans interventions on both climate and non-climate factors driving mosquito-borne disease. Effective tools already exist, so the remaining gap lies in delivery.[1]
Mosquito-borne disease is reaching further into Australia as the climate warms and rainfall patterns shift. Dengue risk could extend south, and Japanese encephalitis has already reached the southern states. The evidence demands attention from every level of government.
Evidence from Queensland and from global malaria control shows that targeted tools can suppress disease despite favourable climate conditions. Success depends on sustained investment, surveillance and rapid response. Delay hands the advantage back to the mosquito.
Accountability rests with governments that fund surveillance, vaccines and vector control. Frontline communities, including Torres Strait Islanders, face the earliest exposure and warrant prioritised protection before the next outbreak arrives. Preparation costs far less than a failed response.
1. Monash University Researchers Warn Climate Change Expands Mosquito Disease Risks . Summarises the Monash review and quotes lead researcher Dr Toby Cumming on climate drivers and coordinated responses.
2. Climate change raises major disease risks for Australia (AAP) . Reports Associate Professor Katie Anders on southern dengue risk, the malaria decline and Wolbachia in northern Queensland.
3. Climate and communicable disease: Discussion paper (CSIRO, 2024) . Rates mosquito-borne disease as the most climate-sensitive communicable disease type and proposes risk assessment criteria.
4. Australia's Dengue Risk Driven by Human Adaptation to Climate Change (PLOS Neglected Tropical Diseases) . Models Aedes aegypti range under 2030 and 2050 scenarios and links domestic water tanks to dengue risk in major cities.
5. Japanese Encephalitis Emergence in Australia: The Potential Population at Risk (Clinical Infectious Diseases) . Documents the 2022 range expansion, its drivers and the population living near infected piggeries.
6. An outbreak of dengue virus type 3 on Mer Island in the Torres Strait, Australia in 2024 (Communicable Diseases Intelligence) . Describes the first detected Torres Strait dengue outbreak since 2017 and the community public health response.
7. Japanese encephalitis: a recent rise in Australian cases (Medicine Today) . Outlines the national significance declaration, infected piggeries and weather drivers behind the 2022 outbreak.
8. Extreme concern over Japanese encephalitis risk this summer (QIMR Berghofer) . Warns of possible endemic spread and limited vaccine supplies after the 2022 outbreak.
9. Policy responses to climate crisis and health in Australia: a need for urgency (Medical Journal of Australia, 2025) . Reviews Japanese encephalitis surveillance and urges a shift beyond reactive responses.
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