New research has shown pigs can contract the bat-borne virus. The finding raises the prospect that pigs could act as intermediate hosts, contracting Hendra from bats and passing it to humans in the same way horses have done.

"The new findings indicate that pigs are susceptible to HeV (Hendra) infections and could potentially play a role as an intermediate host in transmission to humans,'' said a report on the research by Canadian bodies including the National Centre for Foreign Animal Disease.

Hendra is closely related to the potentially fatal Nipah virus - another bat-borne virus found in Southeast Asia which is transmitted from bats to pigs and from pigs to humans.

Dr Peter Reid, an Australian veterinarian involved in the first known Hendra outbreak, said the Canadian research was important. "Hendra is more likely to occur in free range pigs and feral pig populations where fruit bats are, rather than intensive piggeries which are enclosed,'' Dr Reid said.