Is there a connection between Japanese encephalitis (JE) and the NSW and Queensland floods?

Japanese encephalitis (JE), a virus that can attack the neurological system of animals, birds, and humans, was first discovered in Australia late in February.

It has since claimed the life of two Australians, while several other severe cases have been reported in South Australia and Queensland.

Dr Ali Zaid, a viral immunologist and research fellow at the Menzies Health Institute at Griffith University in Queensland told ACM the floods are not entirely to blame for the rise in mosquito populations.

But the increased pooled water had helped to bolster the insect birthrate.

"A lot of rain over the last few months was probably enough to get them started and the floods most likely provided this extra benefit of habitat," Dr Zaid said.

The past few years have been wetter than usual due to the La Nina weather system and experts expected a mosquito-borne virus event.

"It's not just the JE virus, but also other viruses that are carried by mosquitoes that we've known for a long time, happen in Australia and the cases are something that we expect to go up if mosquito populations explode as well," Dr Zaid said.

Pooled water provided a perfect breeding ground for mosquitoes, particularly in warm temperatures.

"If it's not very wet for a long time there is less chance for mosquitoes to find new places to breed," he said.

"That means that they'll be restricted to wherever they've been for as long as the dry period has lasted.

"The more water you provide for them, the more you broaden the ecosystem for them."

Dr Zaid said a lot of surveillance work and entomology work - the study of insects - still needed to be done.

"We're still at the beginning of trying to understand where the virus came from, what it looks like, why it came here and what got it to get this far south," he said.

But only about one per cent of people who contracted the virus showed signs of disease.

"Bear in mind that most mosquito-borne viruses don't have any treatment or preventative strategies, but JE does; there are a couple of vaccines available," he said.