Research into bat-borne viruses in Asia supports links made between outbreaks of the deadly Hendra virus and the mammals' breeding season, an Australian scientist says.

Experts from around the world met on Queensland's Sunshine Coast on Tuesday to discuss rare diseases transmitted by bats to livestock and to humans.

Biosecurity Queensland scientist Dr Hume Field, who gave a presentation on Hendra virus, told AAP later that Australia can expect to have a Hendra outbreak at least once a year, as it has become almost seasonal.

"In the last four or five years there has been an annual spillover of the event and it's all been in the June-July-August time," Dr Field said.

"When we compared that to what was happening in Bangladesh and Thailand we saw the same sort of thing - the clustering (of Hendra and Nipah-like viruses) within a three or four month period.

"In Australia, it's during the time when flying foxes are pregnant."

He said cases of Hendra-like viruses in Asia also appeared to be centred around the bat breeding season.

"Hendra appears to be associated with (bat) pregnancy and lactation but we do need to look for other reasons as to why there is more during that time," he said.

"People need to be aware of it all the time and not just only during that time period."

Horses are believed to contract Hendra when coming into contact with birthing matter dropped on the ground by bats.

The virus is then transmitted from infected horses' secretions to humans.

It has about a 50 per cent mortality rate similar to other viruses like Nipah - a virus from bats to pigs to humans found in Malaysia.

Dr Field said in Bangladesh a Hendra-like virus had about a 75 per cent mortality rate but this could be linked to a lack of medical care available.

Meanwhile, quarantine restrictions have been lifted on properties in central and north Queensland at the centre of the latest Hendra outbreak.

The five remaining properties involved in the recent Hendra virus incidents at Cawarral and Bowen have been given the all-clear with horse test results finalised on Tuesday.

Biosecurity Queensland deputy chief veterinary officer Rick Symons said an all-clear was given only after 32 days had elapsed since the time of last exposure, and definitive test results were negative for Hendra virus.

Veterinarian Dr Alister Rodgers died on September 1 after treating horses stricken with Hendra virus.

Seven people have contracted Hendra virus since 1994 and Dr Rodgers was the fourth of them to die from the disease.