Scientists have discovered that bats are highly likely to be the natural host of the virus responsible for SARS.
Collaborative research involving scientists in Australia, China and the United States concludes that bats are highly likely to be the natural host of the virus responsible for severe acute respiratory syndrome (SARS).
SARS, caused by a previously unrecorded coronavirus, emerged in the southern China province of Guangdong in 2002. By July 2003 it had spread worldwide killing 774 people and infecting a further 8000.
SARS research team leader Dr Linfa Wang, based at Geelong's Livestock Industries' Australian Animal Health Laboratory (AAHL), said although earlier studies indicated a cat-sized mammal found throughout Asia - the civet - could be a natural host of SARS, subsequent studies have revealed no widespread infection in wild or farmed civets.
"Bats are known reservoir hosts of an increasing number of zoonotic viruses [viruses capable of infecting both animals and people], but they rarely display clinical signs of infection," said Dr Wang, whose laboratory is part of part of the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
"It was these characteristics and the fact that bats are present in Asian food markets that led us to survey them," he said.
The study, the results of which have been published in Sciencexpress, the online edition of Science, sampled more than 400 bats in their native habitat from four locations in China.
Blood, faecal and respiratory swabs were collected and independently analysed at AAHL and the Chinese Academy of Sciences' Wuhan Institute of Virology.
"Among the six genera of bats surveyed, three species from the genus Rhinolophus (horseshoe bats) showed high antibody prevalence. More than 70 per cent of R. macrotis bats from Hubei had SARS coronavirus antibodies in their blood, said a research team member from the Queensland Department of Primary Industries and Fisheries, Dr Hume Field.
The serological findings were supported by genetic analysis of the faecal samples.
Dr Wang said: "The viruses detected from bats show greater genetic variation than those SARS coronaviruses which cause disease in humans and other animals. This variation suggest it's highly likely that the 2002/3 SARS outbreak originated from bats."
"Now," added Dr Field, "we need to find out how these viruses 'jump' from bats to other animals and people. This is crucial if we are to manage the risk of future outbreaks."
The five institutions involved in this research were: Institute of Virology and Institute of Zoology, Chinese Academy of Science (China); AAHL; the Department of Primary Industries and Fisheries Queensland; and the Consortium for Conservation Medicine, New York (USA).
Fruit bats in Australia are already known to be reservoirs for Hendra, which can be passed on to horses and then to humans. No cases have been reported of Hendra directly passing from a bat to a human.