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As floodwaters recede in parts of southeast Queensland and northern New South Wales, communities are now facing another challenge—mosquito-borne diseases. Stagnant water left behind by the floods creates ideal breeding grounds for mosquitoes, increasing the risk of infections such as Ross River virus and the potentially fatal Japanese encephalitis virus.
The Mosquito Surge Post-Floods
Following extreme weather events, mosquito populations often surge. In February 2020, floods in northern NSW led to increased cases of Ross River and Barmah Forest virus infections in the months that followed. While a rise in mosquito numbers does not always result in disease outbreaks, experts warn that the combination of flooding and warmer temperatures this year could lead to more cases.
Japanese Encephalitis Virus on the Rise
Despite drier conditions this summer, cases of Japanese encephalitis virus (JEV) have been detected in Victoria, NSW, and Queensland. The virus, which first appeared in southeastern Australia in 2021–22 after extensive flooding, can cause severe illness, including brain inflammation, coma, and, in rare cases, death. This year, human infections have already been recorded, and one fatality has occurred.
The unexpected rise in JEV cases has puzzled scientists, as mosquito numbers remain lower than during past La Niña seasons. Regions such as Darling Downs in Queensland and Moree in NSW, where the virus is already present, may experience further risk with additional rainfall from ex-Tropical Cyclone Alfred.
The Continued Threat of Ross River Virus
Ross River virus infections, though not fatal, can cause debilitating joint pain and fatigue for weeks or even months. Thousands of cases are reported annually, with numbers typically peaking in late summer and early autumn. With heavy rain and flooding in northern Australia this season, there is concern about increased transmission in the coming months.
Protecting Yourself from Mosquito-Borne Diseases
As flood clean-up efforts continue, experts recommend taking precautions to minimize mosquito exposure:
- Eliminate Breeding Grounds: Empty any containers holding stagnant water, including boats, trailers, and debris that can collect water.
- Wear Protective Clothing: Cover up with long-sleeved shirts, long pants, and closed-toe shoes when outdoors.
- Use Insect Repellent: Apply repellents containing DEET, picaridin, or oil of lemon eucalyptus to exposed skin for long-lasting protection.
- Consider Vaccination: Residents in high-risk areas of Queensland, NSW, and Victoria should consult their healthcare provider about the Japanese encephalitis vaccine.
Looking Ahead
Predicting mosquito-borne disease outbreaks remains challenging, as transmission depends on complex factors such as mosquito activity, climate conditions, and wildlife reservoirs. However, the combination of extreme weather and increased mosquito populations raises concerns about potential health risks in flood-affected communities.
Disclaimer: This article provides general information on mosquito-borne disease risks and prevention. For specific health advice, consult medical professionals or local health authorities.
