Hendra outbreak a rain-spawned 'aberration'

TONY MOORE
27 Jul, 2011 11:48 AM


Record-breaking rain over summer has left flying foxes undernourished, with weakened immune systems and a higher amount of Hendra virus in their bodies.

Biosecurity Queensland principal veterinary epidemiologist Hume Field, who played a key role in identifying fruit bats as the natural host of the Hendra virus, said he believed the rain was the reason for the increase in virus cases in 2011.

Dr Field said it was likely the spike in Hendra virus cases this year was a change in flowering patterns of trees since the heavy rainfall from November 2010 to February 2011.

"There is indications that the extensive rainfall last year has disrupted flowering this year, the trees are putting their growth into leaves, rather than flowering," he said.

"That is causing flying foxes to range far and wide in small groups trying to find food.

"That then has the the potential to impact on their immune system to fight off the infection and is likely that the infection in flying foxes is higher this year than in previous years."

Dr Field said the lack of proper food impacted the size of flying fox populations.

"What we are seeing this year is very fragmented flying fox populations, flying foxes that are undernourished," he said.

Dr Hume suspected 2011 was "an aberration", but said studies over time would have to be completed.

However, he ruled out culling as a short-term solution that was "doomed to failure".

"I think culling is not an option," Dr Field said.

"Firstly, flying foxes are not sedentary, they are nomadic, they are a migratory species.

"To suggest a local cull to remove animals from a particular area is doomed to failure because other animals will simply migrate into the space that is left if you like."

Dr Field said the only way culling could be effective was to remove the entire population of flying foxes from Australia.

"Apart from being ethically unacceptable, it would have major biodiversity impacts and unknown impacts," he said.

"So I would seriously suggest that it is not an option."

Dr Hume said the best source of protection was increasing research and by property owners being safe around sick horses and bat populations.
Queensland's chief health officer Jeannette Young said there were 64 people under observation with "low or negligible" symptoms after coming into contact with Hendra virus.