Animals Sold as Delicacy in China May Transmit Virus to Humans

Chinese researchers say they may have found the hitherto elusive source of the SARS outbreak, tracking the virus that causes it to civet cats sold in a Guangdong marketplace and eaten by some Chinese as a delicacy.

Researchers cannot be certain that the virus was originally transmitted to humans from the weasel-like animals -- it’s possible that the virus was transmitted to the mammals by humans instead -- but the discovery represents the strongest support yet for the widely held idea that the disease originated in animals.

“It is highly likely that the virus jumped from civet cats to humans,” microbiologist Dr. Yuen Kwok-yung of the University of Hong Kong said at a news conference Friday.

Other scientists viewed the announcement with some skepticism but welcomed the finding nonetheless. “It’s certainly too early to draw final conclusions on those findings, but they are clearly quite exciting,” said Dr. Francois Meslin of the World Health Organization.

Researchers have been searching for an animal origin for severe acute respiratory syndrome in the hope that it might provide vital clues for the development of treatments and preventive measures, such as a vaccine. The existence of an animal reservoir for the virus, furthermore, might represent a continuing source of new infections for humans, leading to further outbreaks.

Infectious disease specialists know, for example, that there is an animal reservoir for the Ebola virus and that contact between humans and these animals leads to periodic flare-ups of Ebola fever. They have not yet been able to identify that reservoir, however.

Civets, which are more closely related to mongooses than to cats, have catlike bodies, weasel-like faces and flowing tails that are almost as long as their bodies.

Masked palm civets, the species tested by the researchers, are generally 16 to 26 inches long and weigh from 3 to 10 pounds, although they can get heavier. They live primarily in trees, prowling at night to eat insects, fruits, seeds and small vertebrates.

They are considered a culinary delicacy, but they are also hunted for their fur and the musk they secrete, which is used in perfumes. Guangdong merchants keep them in cages, sometimes beating them to death for customers to ensure their freshness. Like other wild animals in the markets, they are often butchered under unsanitary conditions.

Last month, Yuen and his colleagues collected 25 animals of eight species from a marketplace that supplies restaurants in Guangdong province and tested them for the coronavirus that causes SARS.

All six civets that were tested had large amounts of the virus in their stools and respiratory secretions, Yuen said, but all appeared healthy and did not show symptoms similar to those observed in humans.

The team also found the virus in the feces of one raccoon dog -- a member of the dog family that looks remarkably like a raccoon -- and antibodies to the virus in a badger.

But the virus levels were much higher in the civets. Moreover, China only recently began importing the animals from Vietnam in large numbers, according to a WHO official. The time period fits well with the onset of the outbreak in Guangdong province late last year.

Yuen’s team determined the genetic blueprint of the coronavirus isolated from the civets and found that it was identical to the human form of the virus, except that it has a small additional segment on one end of its RNA genome. Experts speculate that the loss of that segment might have allowed the virus to cross into humans.

Eating the animals could be hazardous, but handling them could be even more so, according to WHO experts. Anyone coming into contact with civets’ feces or saliva might be at risk of contracting the virus.

Experts cautioned, however, that the animals could have been exposed to the virus in human excrement that is used as a fertilizer.

They could also have been infected by another species that is the true reservoir of the virus.