Microbiology Research Paper on SARS

Etiology of SARS

The actual reservoir of SARS-CoV in nature is unknown; however, it is suggested that SARS-CoV originated from a wild animal reservoir in mainland China, supported by a number of factors. Masked palm civets and raccoon dogs in animal markets in China had a SARS-CoV almost identical to that seen in SARS patients. Additionally, more than one third of the early SARS patients in Guangdong were involved in either the trade or preparation of food from wild animals in markets.

Furthermore, there was a much higher seroprevalence of SARS-CoV among wild animal handlers than among controls in Guangdong. Further surveillance on animals is needed to help understand the reservoir in nature that led to the SARS outbreak.

Transmission of SARS

The incubation period for SARS is between 3 and 10 days, with a median of 4 to 5 days. However, it may be as long as 14 days. The SARS-CoV is transmitted predominately through droplets from the respiratory tract of the infected person, particularly when coughing, sneezing, and even speaking. The risk of transmission is highest when there is close face-to-face contact. SARS-CoV transmission is believed to be amplified by aerosol-generating procedures such as intubation or the use of nebulizers. The detection of SARS-CoV in fecal as well as respiratory specimens indicates that the virus may be spread by both fecal contamination and via respiratory droplets. SARSCoV also has the ability to survive on contaminated objects in the environment for up to several days and therefore transmission may occur via fomites. Although SARS spreads rapidly around the world as a result of international travel, relatively few cases were acquired by this route (Olowokure, 92).

Efficient environments for transmission of the SARS-CoV were health care facilities and households, leading to a preponderance of SARS cases who were either health care workers or household contacts of cases. Several risk factors may account for this. In the health care setting, close contact is required to care for severely ill patients. Additionally, efficiency of transmission appears to be directly related to the severity of the illness, and those more severely ill are more likely to be hospitalized. Furthermore, patients with SARS-CoV appear to be most infectious during the second week of their illness, and although transmission can also occur during the first week, they are more likely to present to hospital as their clinical condition worsens, usually during the second week. In ...