Experts say record-breaking floods in Australia are allowing mosquitoes to thrive, increasing the risk of spreading diseases like Japanese Encephalitis.

Communities across three states have in recent days been hit by flooding, and more torrential rain is forecast this week. Parts of eastern Australia have been repeatedly flooded in the past two-years.

Mosquitoes need stagnant water. Immature insects emerge from eggs and develop underwater until they become pupae, and then adults. Females require blood before laying eggs and can inject saliva and virus into humans when they bite.

Mosquito-borne diseases are a perennial problem in Australia, where thousands of people are infected with the Ross River virus each year.

In 2021, Japanese Encephalitis gained a significant foothold in Australia for the first time.

More than 40 people were infected with the virus, and seven people died, according to government data.

The virus moves between mosquitos and water birds. Pigs, too, can also harbor the virus.

The illness it causes can be mild, but in some cases, patients can suffer seizures.

Experts have said that fewer than one percent of people infected will develop a severe brain condition — called encephalitis — which can be fatal.

Associate Professor Cameron Webb from the New South Wales Health Department told the Australian Broadcasting Corp. that recent flooding increases the risk of Japanese encephalitis infection.

“There [are] hundreds of different types of mosquitos in Australia, but there is one mosquito in particular that we are concerned about when it comes to Japanese encephalitis virus,” he said. “It is a mosquito that thrives in freshwater environments, the type of environments that have been created by excessive rainfall and flooding across much of the country.”

Two naturally occurring climatic phenomena — La Niña and the Indian Ocean Dipole — are fueling the flooding. Experts have said that their impact is being intensified by climate change.

Australian troops and residents have been racing to build a two kilometers long levee to stop floodwaters from inundating the town of Echuca, north of Melbourne. Parts of eastern Australia have had their worst flooding in decades.

With heavy rain in the forecast later this week, regions from Queensland to Tasmania in eastern Australia are once again on flood watch.
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