Biosecurity Queensland says the rate of Hendra virus infection in flying foxes has quadrupled.
Almost one third of Queensland's bats are now infected with the Hendra virus, more than four times the normal rate, new tests reveal.
Based on research on infected bat populations earlier this year, Biosecurity Queensland last night confirmed the rate of Hendra virus infection has quadrupled.
Studies done during the current incidents indicate that up to 30 per cent of flying foxes are carrying the virus
Biosecurity Queensland bat expert Dr Hume Field said the summer floods and cyclones had increased the number of malnourished bats, putting them at risk of becoming infected.
"Studies done during the current incidents indicate that up to 30 per cent of flying foxes are carrying the virus," a Biosecurity Queensland spokesperson confirmed.
"Normally the infection rate in Queensland flying fox colonies is around seven per cent."
However a bat infected with Hendra doesn't necessarily carry enough of the virus to pose a risk of passing it on to a horse or another animal.
Tests this year were carried out at Logan, Boondall, Hervey Bay, Beaudesert, Mt Alford, Park Ridge, Kuranda and Chinchilla.
The figures come as vets call for the state government to re-introduce a bat cull, claiming Queensland's bat population has tripled since 2007.
Brian White, an agricultural scientist who runs an equestrian centre in Brisbane's semi-rural Moggill, said Queensland's overpopulation of bats had triggered the high Hendra infection rate.
He said the Queensland Government must re-consider culling bats, a measure it ruled out in 2008.
"The cull needs to be done regularly, because if we don't do it that way we end up with this situation where you have a population explosion and environmental factors like the cyclones and the floods affecting their food supply," he said.
"It creates that perfect storm situation for the Hendra virus."
Mr White said the research by Dr Field showed overpopulation stressed bats, which led to their increased susceptibility to Hendra virus.
However Dr Field said culling was "doomed to failure" and described the current situation as an "abberation" triggered by low food and stressed bats.
Mr White disagreed, saying the breeding population had reached a tipping point.
"We are probably looking at a [bat] population of three times the 2007 year, combined with a massive food shortage caused by the cyclones and the floods," he said.
Moggill vet Mandy Finnimore said vets were told last Friday by CSIRO bat expert Dr Linfa Wang that infection rates in some bat populations reached between 30 and 60 per cent.
However the 60 per cent figure was dismissed last night by Biosecurity Queensland.
Bat experts agree the creatures are very nomadic, with little red bats favouring flowering eucalypts as foods, while black and grey species prefer fruit-growing regions.
Yesterday, it was announced Hendra virus research funding would be increased by $6 million over the next three years.
The extra funding will allow scientists to study bat populations at night, using infra-red cameras, Premier Anna Bligh said.
"So you are going to see scientists with infra-red cameras out monitoring bat and horse populations in Queensland and New South Wales in high risk areas," she said.
"They will get a better understanding of not only what is happening at day time, but what is happening at night with these species."
Meanwhile, Brisbane City Council said it would wait for advice from the Department of Environment and Resource Management before deciding to allow vegetation to be cleared, as suggested yesterday by Liberal National Party leader Campbell Newman.
On June 30 Lord Mayor Graham Quirk said the emphasis needed to be on finding a human vaccine for Hendra virus.
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