Severe Acute Respiratory SyndromeOverview

Severe acute respiratory syndrome (SARS) is a serious, potentially life-threatening viral infection in humans caused by a previously unrecognized virus from the Coronaviridae family. This virus has been named the SARS-associated coronavirus (SARS-CoV). Previously, Coronaviridae were best known as the second most common cause of the common cold. SARS is associated with the onset of a flulike syndrome, which may progress to pneumonia, respiratory failure, and, in some cases, death. There was one major epidemic to date, between November 2002 and July 2003, with 8,096 known cases of the disease, and 774 deaths (a mortality rate of 9.6%) being listed in the World Health Organization's April 21, 2004 concluding report. This outbreak of SARS affected mainland China (5327 cases, 349 deaths), Hong Kong (1755 cases, 299 deaths), Singapore, and Taiwan (346 cases, 37 deaths). Canada experienced a significant outbreak in the area around Toronto, Ontario (251 cases, 43 deaths). In the United States, 8 individuals contracted laboratory-confirmed SARS. All patients had travelled to areas where active SARS-CoV transmission had been reported.
Although not strictly an STD, SARS can be transmitted through sexual contact, its primary means of transmission being close person-to-person contact. When someone with SARS coughs or sneezes, infected droplets are sprayed into the air. Like other coronaviruses, the SARS virus may live on hands, tissues, and other surfaces for up to 6 hours in these droplets and up to 3 hours after the droplets have dried.
The incubation period of SARS ranges between 2 to 7 days, although it may be as long as 10 days and rarely 14 days.

SIGNS AND SYMPTOMS

SARS develops in two stages. The first stage begins approximately 2-7 days after exposure to the virus and is characterized by flulike symptoms. These symptoms include fever (>100.4F [38C]), fatigue, headaches, chills, gastrointestinal symptoms, cough, sore throat, myalgias, malaise, anorexia, and, sometimes, diarrhea. This stage lasts 3-7 days.
The second stage begins 3 or more days after the initial infection and it is characterized by a dry cough, dyspnea (shortness of breath, difficult or laboured breathing), and, in many cases, progressive hypoxemia (low oxygen levels in the blood). Approximately 1020% of cases require mechanical ventilation (the use of a mechanical device to inflate and deflate the lungs).
Clinical investigations leading to the diagnosis of SARS include: chest X-ray or chest CT scan, complete blood count (CBC) (White blood cell, lymphocyte, and platelet count may be low), blood clotting tests, blood chemistries (LDH levels, ALT and CPK are sometimes elevated, sodium and potassium are sometimes low).
There also specific tests such as ELISA (enzyme-linked immunosorbent assay), which can detect antibodies to SARS 21 days after the onset of the symptoms, an immunofluorescence assay, which can detect the antibodies 10 days after the onset of the disease, and the last one is a PCR (polymerase chain reaction) test that can detect genetic material of the SARS virus in specimens ranging from blood, sputum, tissue samples and stools. The latter has proved to be not very specific, which means that a positive result certainly indicates an infection with SARS while a negative result does not exclude the possibility that the person is infected with SARS.

TREATMENT

Currently, no definitive medication protocol specific to SARS has been developed, although various treatment regimens have been tried without proven success. The typical treatment approved by the CDC is that administered to any serious community-acquired pneumonia.
Antibiotics are not indicated because SARS is a viral infection. Various steroid regimens have been used around the world as part of the initial SARS treatment cocktail, but they have not subsequently been confirmed in a clinical trial. Other treatments include antiviral medications such as Ribavirin (usually in conjunction with steroids), and interferon, but no published evidence has supported this therapy.
In December 2004 it was reported that Chinese researchers had produced a SARS vaccine. It has been tested on a group of 36 volunteers, 24 of whom developed antibodies against the virus.

COMPLICATIONS

As with most viral illnesses, SARS encompasses a spectrum of disease severity. Mortality statistics have shown a significant increase with advancing age. Mortality rates are approximately 4-5% in the third decade of life or younger and are approximately 50% in patients older than 65 years. The overall mortality rate is approximately 10%. Recovery may be prolonged, including care in an ICU setting and mechanical ventilation. Complications related to a prolonged illness (e.g. deep venous thrombosis, myocardial infarction, and stroke) can occur.

PREVENTION

SARS infection may be prevented by minimizing contact with infected persons, which means to avoid travelling to locations where there is an uncontrolled outbreak. The CDC has identified hand hygiene as the cornerstone of SARS prevention. This might include hand washing or cleaning hands with an alcohol-based instant hand sanitizer.
People should be taught to cover the mouth and nose when sneezing or coughing. Respiratory secretions should be considered to be infectious, which means no sharing of food, drink, or utensils. Commonly touched surfaces can be cleaned with an EPA disinfectant.
Since it can be sexually transmitted, SARS may be prevented by reducing the number of sex partners.