Severe Acute Respiratory Syndrome (SARS) is a potentially fatal pneumonia-like illness with outbreaks reported in Asia, North America, and Europe. Almost 3,000 cases have been reported worldwide since November 2002, of which the overwhelming majority are located in Pacific Asia, primarily China. The federal government has added SARS to the list of quarantinable communicable diseases under the Public Health Service Act.
SARS is most likely viral in origin and is apparently contagious primarily through long-term, close contact. The majority of identified SARS patients to date have been adults aged 25 to 70. Until recently, few patients under age 15 were reported, but there are now reports of SARS striking children as young as 3 to 4 years of age.
The alarming Severe Acute Respiratory Syndrome epidemic is only months old, and yet its rapid global spread - fueled in part by international travel - has prompted fast, proactive, technology-assisted initiatives by public health officials and scientists. While work has reportedly begun on the development of a vaccine, some experts are already concerned that containment efforts will not catch up with the rapidly expanding pandemic.
The severity of SARS seems highly variable, ranging all the way from mild illness to death. In 10-20% of cases, the illness becomes severe enough to require mechanical breathing support. The fatality rate among SARS patients is approximately 3%, according to a recent CDC report.
Cases of SARS occur primarily among people who have had direct, close contact with an infected person, such as sharing a household, or have been providing health care without using infection control procedures. The pneumonia-like illness has also occurred among air travelers, primarily travelers to and from Hong Kong, Hanoi, Singapore, and mainland China - the areas where SARS originated.
While a few close contacts of SARS patients have developed a similar illness, the majority have remained well, according to CDC data. Some close contacts have reported a mild fever without respiratory symptoms. This suggests that SARS might not always progress to the respiratory phase.
The illness appears to be spread when a SARS patient coughs or sneezes droplets into the air and someone else breathes them in. It is also possible that SARS can be communicated through the air or from contact with contaminated objects, but observations so far are not conclusive.
The appearance of SARS in some health-care settings has mostly resulted from late implementation of effective procedures for health-care workers. Since early recognition and isolation of possible SARS patients is critical, the CDC has published recommended guidelines for triage of potential SARS cases.
SARS is most likely viral in origin. Several viruses are being studied as potential causes. Supportive evidence points strongly to a newly discovered type of coronavirus detected in several patients. Previously known corona ("crown-shaped") viruses are common causes of upper-respiratory illness, although usually of only mild to moderate intensity. The new coronavirus is being tested against existing antiviral drugs.
Other virus types that are being investigated for a possible role in causing SARS include the metapneumovirus and paramyxovirus (relatives of viruses that cause mumps, measles, and croup).