Severe Acute Respiratory Syndrome

Current state of etiologic knowledge

The etiology of SARS is still being explored. On April 7, 2003, WHO announced that it was generally agreed that a newly identified coronavirus is the major causative agent of SARS, and that the significance of a human metapneumovirus (hMPV) in SARS remains unclear and would continue to be studied. http://www.who.int/csr/sars/findings/en/ This was followed by an announcement on April 16 that scientists at Erasmus University in Rotterdam, the Netherlands have confirmed that the virus causing SARS is indeed the new coronavirus. In the experiments, monkeys were infected with the coronavirus, and it was observed that they developed the same symptoms as human SARS victims.

Related Topics:
Etiology - April 7 - 2003 - April 16 - Erasmus University - Rotterdam - Netherlands - Monkeys

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Initially, electron microscopic examination in Hong Kong and Germany found viral particles with structures suggesting paramyxovirus in respiratory secretions of SARS patients; subsequently, in Canada, electron microscopic examination found viral particles with structures suggestive of metapneumovirus (a subtype of paramyxovirus) in respiratory secretions. Chinese researchers also reported that a chlamydia-like disease may be behind SARS. The Pasteur Institute in Paris identified coronavirus in samples taken from six patients. The CDC, however, noted viral particles in affected tissue (finding a virus in tissue rather than secretions suggests that it is actually pathogenic rather than an incidental finding). On electron microscopy, these tissue viral inclusions resembled coronaviruses, and comparison of viral genetic material obtained by PCR with existing genetic libraries suggested that the virus was a previously unrecognized coronavirus. Sequencing of the virus genome—which computers at the British Columbia Cancer Agency in Vancouver completed at 4 a.m. Saturday, April 12, 2003—was the first step toward developing a diagnostic test for the virus, and possibly a vaccine. http://www.bayarea.com/mld/mercurynews/news/5629349.htm A test was developed for antibodies to the virus, and it was found that patients did indeed develop such antibodies over the course of the disease, which is very suggestive that the virus does have a causative role. It is generally agreed that this coronavirus has a causative role in SARS: continued study is underway to test the hypothesis that co-infection with other organisms such as human metapneumovirus may also play a role.

Related Topics:
Electron microscopic - Viral - Paramyxovirus - Canada - Metapneumovirus - Chlamydia - Pasteur Institute - Paris - PCR - Genome - Vancouver - April 12 - 2003 - Antibodies

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An article published in The Lancet identifies a coronavirus as the probable causative agent.

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On April 16, 2003, the WHO issued a press release stating that the coronavirus identified by a number of laboratories was the official cause of SARS. http://www.who.int/mediacentre/releases/2003/pr31/en/

Related Topics:
April 16 - 2003

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In late May 2003, studies from samples of wild animals sold as food in the local market in Guangdong, China found that the SARS coronavirus could be isolated from civet cats. This suggests that the SARS virus crossed the species barrier from civet cats; this conclusion is, however, by no means certain as it is certainly possible that the civet cats got the virus from humans and not the other way around or even that the civet cats are a sort of intermediary host. In September 2005, a study was released from China which found that 40 percent of a sample of Horseshoe bats collected near Hong Kong were infected with a close genetic relative of SARS, raising the possibility that SARS originated in bats and spread to humans either directly, or through civet cats. The bats did not show any visible signs of disease. http://news.yahoo.com/s/ap/20050910/ap_on_sc/sars_batsFurther investigations are ongoing.

Related Topics:
Civet - Species barrier - Horseshoe bats

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