Across the world, mosquito-borne diseases like Dengue, Malaria, and Zika virus are on the rise, spreading into regions previously considered low-risk. Many experts are turning their attention to climate change, highlighting its growing influence on the spread of mosquito-borne illnesses.

Experts from Stanford University and other climate researchers caution that climate change is driving more extreme weather—both floods and droughts—which, ironically, can each increase the risk of mosquito-borne diseases. Floodwaters create stagnant pools ideal for mosquito breeding, while drought often leads people to store water around their homes, providing mosquitoes with yet another breeding ground.

Australians are no strangers to the impacts of extreme weather. This summer has already seen sweltering heatwaves scorch parts of the country, while other regions battle floods and heavy rainfall. These weather extremes are not only disruptive—they’re also creating the perfect breeding conditions for mosquitoes, raising concerns of an increase in mosquito-borne illnesses.

The link between climate change and mosquito-borne diseases

While mosquitoes have always been part of life in Australia, their growing connection to disease outbreaks is becoming harder to ignore. But how exactly does climate change fuel this increase in disease? The answer lies in the mosquito’s unique relationship with temperature, moisture, and human environments.

Warmer temperatures speed up disease transmission

Mosquitoes are cold-blooded creatures, meaning their body temperature depends on their environment. As global temperatures rise, mosquitoes develop faster, bite more frequently, and reproduce at an accelerated rate.

But the heat doesn’t just make mosquitoes more active—it also affects the viruses and parasites they carry. Warmer weather shortens the time it takes for a virus (such as Dengue or Malaria) to develop inside a mosquito, meaning infected mosquitoes can start transmitting diseases sooner.

In places like northern Australia, where temperatures are climbing, this means longer mosquito seasons, faster transmission cycles, and a greater risk of outbreaks.

More rain, more mosquitoes

Australia’s climate is becoming increasingly unpredictable, swinging between searing heatwaves and torrential downpours that cause flooding. While heavy rain might seem like it would wash mosquitoes away, it actually leaves behind pools of stagnant water—the ideal breeding ground for mosquito larvae.

Flooded parks, waterlogged gardens, and blocked drains quickly become nurseries for mosquito populations, allowing mosquito numbers to surge in the days and weeks following extreme rainfall.

Even urban areas aren’t spared—water trapped in pot plants, buckets, or clogged gutters provides mosquitoes with everything they need to multiply right outside our homes.

Extreme weather creates long-term risk

It’s not just heat and rain on their own—extreme weather events like cyclones, floods, and droughts compound the problem.

• Flooding leaves water everywhere, creating vast breeding sites.
• Drought forces people to store water, often in open containers that attract mosquitoes.
• Cyclones and storms can displace communities, forcing people into crowded shelters where disease transmission is more likely.

So, while climate change doesn’t introduce mosquitoes or diseases into Australia, it creates the perfect condition for both to flourish.

Mosquito-borne diseases in Australia

Right here at home, mosquitoes are responsible for spreading a range of potentially serious viruses, some of which are becoming more concerning as our climate shifts.

While not every mosquito carries disease, certain species in Australia act as carriers (or vectors) for viruses that can cause debilitating symptoms—and, in rare cases, life-threatening complications. Here’s a closer look at some of the key mosquito-borne diseases in Australia:

1. Ross River Virus

Ross River Virus (RRV) is the most common mosquito-borne disease in Australia, with hundreds to thousands of cases reported every year. It’s widespread across the country, but outbreaks tend to surge after periods of heavy rain and flooding (generally between February to May), particularly in Queensland, New South Wales, and Victoria.

While not life-threatening, RRV can cause persistent joint pain, fatigue, and flu-like symptoms, which can last for weeks—or even months—for some people.

2. Barmah Forest Virus

Similar to Ross River Virus, Barmah Forest Virus is another virus spread by mosquitoes in Australia, causing joint pain, rash, and fatigue. It’s less common than RRV, but cases still appear across many parts of the country, particularly in rural and regional areas with wetlands or after flooding.

While most people recover within a few weeks, some experience lingering joint pain and tiredness.

3. Dengue Fever

Dengue Fever is a well-known mosquito-borne disease globally, but outbreaks also occur in northern Australia, particularly in Far North Queensland. Aedes aegypti mosquitoes, which thrive in urban environments, are the main carriers of Dengue, and cases tend to increase after the wet season, especially when stagnant water accumulates around homes.

Symptoms can range from mild fever to severe muscle pain, rash, and bleeding, with severe cases requiring hospitalisation.

4. Murray Valley Encephalitis (MVE)

A rarer but more serious virus, Murray Valley Encephalitis (MVE) is native to Australia, typically emerging after floods along river systems in the Murray-Darling Basin and northern regions. MVE is carried by mosquitoes that have bitten infected waterbirds, and while infections are rare, the disease can be fatal.

Symptoms can start with headaches, nausea, and dizziness, but in severe cases, it can progress to brain inflammation (encephalitis), causing seizures, confusion, and even coma.

5. Japanese Encephalitis (JE)

Japanese Encephalitis (JE) was once thought to be a concern mainly for parts of Asia, but recent outbreaks in Australia have put this virus firmly on the radar, particularly in southeastern regions and areas near pig farms. Like MVE, JE can lead to encephalitis (brain inflammation), with a small percentage of cases resulting in severe neurological damage or death.

Floods, wetlands, and stagnant water contribute to mosquito breeding, and pig farms are known amplifying hosts, increasing transmission risk during outbreaks. Vaccination is available for those in high-risk areas, particularly agricultural workers and those living near affected regions.

Protect yourself from mosquito-borne diseases

While climate change and shifting mosquito patterns may feel beyond our control, there’s still a great deal individuals can do to reduce their risk of bites and the diseases mosquitoes carry, whether you’re spending time outdoors, relaxing at home, or travelling to mosquito-prone regions.

1. Apply insect repellent

One of the simplest and most effective defences is using insect repellent. Products containing DEET or Picaridin are proven to offer long-lasting protection against mosquitoes.

• DEET-based repellents are highly effective, though some people may find them strong-smelling or harsh on sensitive skin.
• Picaridin repellents are a milder alternative but still provide robust protection, making them a great option for families and those with skin sensitivities.
• Natural repellents using plant-based oils like lemon eucalyptus or tea tree can be helpful for light outdoor use, though they may need to be reapplied more frequently.

Whichever repellent you choose, applying it consistently is crucial—especially during dawn, dusk, and after rain, when mosquitoes are most active.

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Climate Change Extreme Weather Health & Wellbeing Insect Repellent Mosquito Mosquito-borne diseases Pest Control Safety & Protection Seasonal Care Summer