SARS, or severe acute respiratory syndrome, is the disease caused by SARS-CoV. It causes an often severe illness and is marked initially by systemic symptoms of muscle pain, headache, and fever, followed in 2–14 days by the onset of respiratory symptoms, mainly cough, dyspnea, and pneumonia. Another common finding in SARS patients is a decrease in the number of lymphocytes circulating in the blood.
In the SARS outbreak of 2003, about 9% of patients with confirmed SARS-CoV infection died. The mortality rate was much higher for those over 60 years old, with mortality rates approaching 50% for this subset of patients.
On 12 April 2003, scientists working at the Michael Smith Genome Sciences Centre in Vancouver finished mapping the genetic sequence of a coronavirus believed to be linked to SARS. The team was led by Marco Marra and worked in collaboration with the British Columbia Centre for Disease Control and the National Microbiology Laboratory in Winnipeg, Manitoba, using samples from infected patients in Toronto. The map, hailed by the WHO as an important step forward in fighting SARS, is shared with scientists worldwide via the GSC website (see below). Donald Low of Mount Sinai Hospital in Toronto described the discovery as having been made with "unprecedented speed". The sequence of the SARS coronavirus has since been confirmed by other independent groups.
In late May 2003, studies from samples of wild animals sold as food in the local market in Guangdong, China, found a strain of SARS coronavirus could be isolated from masked palm civets (Paguma sp.), but the animals did not always show clinical signs. The preliminary conclusion was the SARS virus crossed the xenographic barrier from palm civet to humans, and more than 10,000 masked palm civets were killed in Guangdong Province. The virus was also later found in raccoon dogs (Nyctereuteus sp.), ferret badgers (Melogale spp.), and domestic cats. In 2005, two studies identified a number of SARS-like coronaviruses in Chinese bats.
Phylogenetic analysis of these viruses indicated a high probability that SARS coronavirus originated in bats and spread to humans either directly or through animals held in Chinese markets. The bats did not show any visible signs of disease, but are the likely natural reservoirs of SARS-like coronaviruses. In late 2006, scientists from the Chinese Centre for Disease Control and Prevention of Hong Kong University and the Guangzhou Centre for Disease Control and Prevention established a genetic link between the SARS coronavirus appearing in civets and humans, confirming claims that the virus had jumped across species.
^Fehr, Anthony R.; Perlman, Stanley (2015). "Coronaviruses: An Overview of Their Replication and Pathogenesis". Coronaviruses. Methods in Molecular Biology. 1282. Clifton, New Jersey, USA. pp. 1–23. doi:10.1007/978-1-4939-2438-7_1. ISBN978-1-4939-2437-0. ISSN1064-3745. PMC4369385. PMID25720466. SARS-CoV primarily infects epithelial cells within the lung. The virus is capable of entering macrophages and dendritic cells but only leads to an abortive infection [87,88].