Coronavirus outbreak in cheetahs: Lessons for SARS

In November 2002, a flu-like outbreak caused by a coronavirus now known as SARS-CoV occurred in Guangdong Province in China. In the space of 9 months the disease traveled to 29 countries, infected 8098 people and caused 774 deaths [1]. The SARS epidemic spread with alarming speed among health care workers attending SARS patients (e.g., 112 health care workers at Prince of Wales hospital in Hong Kong became infected contemporaneously), but also indirectly among residents of an apartment complex, many who did not have physical contact with a clinically ill patient. Although the epidemic subsided by May 2003, there is still no clear understanding of the precise mode of transmission, no firm laboratory based diagnostic test, no vaccine, and no efficient treatment for SARS [2]. Recently published reports show that a virus closely related to the SARS-CoV was discovered in samples collected in Chinese food markets from Himalayan palm civets, raccoon dogs, snakes, bats and monkeys [3,4], and that SARS-CoV can infect domestic cats and ferrets [5]. Yet unconfirmed results [3,4] imply that Himalayan palm civets are one animal reservoir for SARS-CoV, and suggest that the deadly SARS-CoV recently emerged from an animal species. A fatal epizootic of a related coronavirus in captive African cheetahs at Winston Safari park in the early 1980s may offer comparative insight into the prospects for a coronavirus-based epidemic [6]. The affected animals died of feline infectious peritonitis (FIP), caused by a feline coronavirus (FCoV, also called FIPV). The presence of a cheetah coronavirus (Aju-CoV, for Acinonyx jubatus coronavirus) was inferred based upon the presence of FIPV antibodies and the observation of coronavirus-like particles [6,7]. In domestic cats FCoV occurs in two varieties: virulent FIPV which causes severe FIPV antibody mediated fatal disease in about 5–10% of infected cats, and a subclinical enteric feline coronavirus (FECV) infection. Within months of arrival of the two infected cheetahs to Winston Safari, other cheetahs in the park fell ill. Retrospective serum samples tested for antibodies demonstrated that prior to 1982 all cheetah serum were negative, but within six months of the Sacramento cheetahs' arrival, 100% of the cheetahs had seroconverted, most with titers >1600 (Supplemental Figure S1). Ninety percent of the 60 cheetahs in the park developed disease symptoms including jaundice, diarrhea, weight loss, gingivitis, hepatic and renal pathology. With a mortality of 60% within 2–3 years, this was the most extreme outbreak of coronavirus in any species …