Frequently Asked Questions about SARS and Other Coronaviruses

What causes SARS?
Scientists at the Centers for Disease Control and other laboratories have detected a previously unrecognized coronavirus in patients with SARS. This new coronavirus is the leading hypothesis for the cause of SARS. Prior to SARS, coronaviruses appeared in humans and caused mild disease, most often the common cold. Coronaviruses cause more severe diseases in animals, however, which has led some researchers to speculate that the coronavirus detected in SARS patients originated there.

“Presumably, this virus originated in animals and mutated or recombined in a fashion that permitted it to infect, cause disease, and pass from person to person,” Dr. Thomas Ksiazek, a veterinarian with the Centers for Disease Control, wrote in the April 10, 2003 New England Journal of Medicine. “The available sequence data on this coronavirus suggest that it is sufficiently distinct from those previously reported in animals and humans that its source may be yet to be discovered.”

What is a coronavirus?
Coronaviruses are a group of viruses that have a halo or crown-like (corona) appearance when viewed under a microscope. These viruses are a common cause of mild to moderate upper-respiratory illness in humans and are associated with respiratory, gastrointestinal, liver, and neurologic disease in animals, including cats, dogs, pigs, mice, and birds. The most common encountered by pet owners are feline infectious peritonitis (FIP) and canine coronavirus. Canine coronavirus is not a serious disease, but FIP is particularly devastating for young cats coming from purebred catteries and shelters. It can cause up to 5 percent mortality over the long run. Almost all cats that get FIP will die. This severity has researchers concerned about coronaviruses in humans.

“Although the known human coronaviruses are associated with a mild disease (the common cold), the ability of coronavirus to cause severe disease in animals raises the possibility that coronavirus could also cause more severe disease in humans,” Dr. Ksiazek wrote. “Other than rare instances in children or immunocompromised patients, it appears that SARS-related coronavirus may be the first example of a coronavirus that causes severe disease in humans.”

Can my dog, cat, or bird contract SARS?
Chinese authorities and media have spread misleading information on this point, which contributed to the pet panic gripping the country. One news story described three ill dogs discovered in Beijing (two of which were foaming at the mouth) and said they were suspected of having SARS. They may have been suspect, but chances are they did not have the disease.

“There have been no recognized cases of SARS-like disease in pet dogs, birds, or cats, so we have to assume that they are not susceptible,” Dr. Niels Pedersen of UC Davis told the CVMA. “Coronaviruses are very species adapted, and the SARS coronavirus has only a 60 percent genetic relationship with known coronaviruses of dogs, cats, cattle, mice, chickens, and humans. This relationship is really quite small and prevents the SARS agent from easily jumping from man into our pets .”