Bushra Jamil, Kiren Habib.
Mers-cov - are we on the verge of a pandemic?.
J Pak Med Assoc Jan ;63(11):1329-31.

Coronaviruses are single stranded RNA viruses found throughout the world. The six well-known human coronaviruses are 229E, OC43, NL63, HKU1, SARS-CoV1,2 and the most recently discovered Middle Eastern Respiratory Syndrome coronavirus (MERS-CoV). Coronaviruses, commonly associated with colds and upper respiratory tract infections, are also known to cause pneumonia in the elderly and immunocompromised individuals. The most well-known outbreak caused by a coronavirus in recent times was the SARS outbreak (2002-2003) which began in China and rapidly spread throughout the world leading to about 8000 cases and 700 deaths.3 The origin was later linked to bats which are commonly sold in markets in China, primarily as food for civet cats, which in turn serve as a delicacy for humans. With stringent infection control measures worldwide, the outbreak was eventually curtailed and there have been no new reported cases after 2004. MERS-CoV-related illness was first recognized in early 2012. The origin of the virus however, remains unknown. MERS-CoV virus is thought to be an animal virus; humans are infected sporadically. The "alternative explanation to explain the sporadic appearance of severe human cases with long periods of time between them, and the wide geographical area over which the virus was apparently distributed, is unrecognized ongoing transmission in people. Surveillance efforts since the discovery of the virus and retrospective testing of stored respiratory specimens suggest this is not the case."4

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