Severe acute respiratory syndrome (SARS) is a viral respiratory disease of zoonotic origin caused by the virus SARS-CoV-1, the first identified strain of the SARS-related coronavirus. The first known cases occurred in November 2002, and the syndrome caused the 2002–2004 SARS outbreak. In the 2010s, Chinese scientists traced the virus through the intermediary of Asian palm civets to cave-dwelling horseshoe bats in Xiyang Yi Ethnic Township, Yunnan. SARS was a relatively rare disease; at the end of the epidemic in June 2003, the incidence was 8,422 cases with a case fatality rate (CFR) of 11%. No cases of SARS-CoV-1 have been reported worldwide since 2004. In December 2019, a second strain of SARS-CoV was identified: SARS-CoV-2. This strain causes coronavirus disease 2019 (COVID-19), the disease behind the COVID-19 pandemic.
Signs and symptoms SARS produces flu-like symptoms which may include fever, muscle pain, lethargy, cough, sore throat, and other nonspecific symptoms. SARS often leads to shortness of breath and pneumonia, which may be direct viral pneumonia or secondary bacterial pneumonia. The average incubation period for SARS is four to six days, although it is rarely as short as one day or as long as 14 days.
Transmission The primary route of transmission for SARS-CoV is contact of the mucous membranes with respiratory droplets or fomites. As with all respiratory pathogens once presumed to transmit via respiratory droplets, it is highly likely to be carried by the aerosols generated during routine breathing, talking, and even singing. While diarrhea is common in people with SARS, the fecal–oral route is another mode of transmission. The basic reproduction number of SARS-CoV, R0, ranges from 2 to 4 depending on different analyses.
Diagnosis
SARS-CoV may be suspected in a patient who has:
Traveled to China or Taiwan or has been in close contact with an ill person from those areas, A laboratory worker or a healthcare in contact with a laboratory worker in contact with live SARS-COV-1 virus, A patient with atypical pneumonia and no alternative diagnosis. The appearance of SARS-CoV in chest X-rays is not always uniform but generally appears as an abnormality with patchy infiltrates.
Prevention In 2017 immunologist Anthony Fauci said the CDC had developed a vaccine for SARS-COV-1 and placed it in the Strategic National Stockpile. The vaccine was not deployed because public health measures defeated the outbreak. A vaccine developed by a team led by Peter Hotez sits in a freezer at the University of Texas. To prevent the spread of SARS in a hospital setting, detection and strict clinical isolation is combined with droplet and contact contamination prevention measures through the use of personal protective equipment. Tracing and quarantine of people who contact infected individuals is effective in preventing the spread in the community. Public health measures ended the 2002 SARS outbreak. No cases have been reported since 2004. Precautions recommended should an outbreak reoccur include:
Hand-washing with soap and water, or use of alcohol-based hand sanitizer Wearing masks and gloves Washing the personal items of someone with SARS in hot, soapy water (eating utensils, dishes, bedding, etc.) Disinfect any surfaces which may have come in contact with any bodily fluids of an infected person. A 2017 meta-analysis found that for medical professionals wearing N-95 masks could reduce the chances of getting sick up to 80% compared to no mask. A screening process was also put in place at airports to monitor air travel to and from affected countries. SARS-CoV is most infectious in severely ill patients, which usually occurs during the second week of illness. This delayed infectious period meant that quarantine was highly effective; people who were isolated before day five of their illness rarely transmitted the disease to others. As of 2017, the CDC was still working to make federal and local rapid-response guidelines and recommendations in the event of a reappearance of the virus.
Treatment
There is no treatment shown to be effective against SARS; some attempted treatments may have been harmful. As SARS is a viral disease, antibiotics do not have direct effect but may be used against bacterial secondary infection. Treatment of SARS is mainly supportive with antipyretics, supplemental oxygen and mechanical ventilation as needed. While ribavirin is commonly used to treat SARS, there seems to have little to no effect on SARS-CoV, and no impact on patient's outcomes. There is currently no proven antiviral therapy. Tested substances include ribavirin, lopinavir, ritonavir, type I interferon, but have thus far shown no conclusive contribution to the disease's course. Administration of corticosteroids, is recommended by the British Thoracic Society/British Infection Society/Health Protection Agency in patients with severe disease and O2 saturation of <90%. People with SARS-CoV must be isolated, preferably in negative-pressure rooms, with complete barrier nursing precautions taken for any necessary contact with these patients, to limit the chances of medical personnel becoming infected. In certain cases, natural ventilation by opening doors and windows is documented to help decreasing indoor concentration of virus particles. Some of the more serious damage caused by SARS may be due to the body's own immune response. Understanding this effect maybe critical to developing effective treatments.
Vaccine Vaccines can help the immune system to create enough antibodies and decrease a risk of side effects like arm pain, fever, and headache. According to research papers published in 2005 and 2006, the identification and development of novel vaccines and medicines to treat SARS was a priority for governments and public health agencies around the world. In early 2004, an early clinical trial on volunteers was planned. A major researcher's 2016 request, however, demonstrated that no field-ready SARS vaccine had been completed because likely market-driven priorities had ended funding.
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