Clusters of coronavirus cases put scientists on alert.


Is the coronavirus that has appeared in the Middle East a simmering threat to global public health or a viral footnote that will end up being of interest only to academics? That is the key question that researchers and public-health officials are now struggling to resolve. Two unsettling developments have fed their concerns: fresh hints that the virus might show at least limited spread from person to person, and signs that it has extended its geographical range. Last week, the World Health Organization (WHO) urged that surveillance for the virus, called human betacoronavirus 2c EMC/2012, should be extended to all countries worldwide, with a special focus on all clusters of severe pneumonia, particularly in health workers. Epidemiologists say that the nebulous threat requires close monitoring, by investigating and controlling any new clusters of human cases that could signal that the virus has adapted to spread between people more easily. The coronavirus, first reported on 20 September, causes severe pneumonia and often kidney failure. In the nine cases confirmed so far, it has had a death rate of more than 50%. “It’s an extremely serious disease; it’s very much in the category of H5N1 [avian influenza],” says David Heymann, chairman of the UK Health Protection Agency and former head of the communicable-diseases programme at the WHO during the 2003 SARS epidemic, caused by a different coronavirus. Yet this latest coronavirus is still limited to the Middle East and shows no sign of spreading easily between people, Heymann emphasizes. In late November, however, the WHO reported a household cluster of four cases in Saudi Arabia, in which two people died. Retrospective tests looking for the coronavirus in samples from a cluster of 11 people who were admitted with serious respiratory symptoms to a hospital in Jordan in April have revealed the virus in another two fatal cases. This pushes back the first known date of its emergence by several months and marks the first evidence for infection outside Saudi Arabia and Qatar. Although independent infections from the same animal or environmental source might explain these outbreaks, such clusters always raise the possibility of transmission between humans. Because the disease did not spread any further, however, person-to-person transmission of the virus — if it occurred at all — would have had to have been through close contact. Still, the extension of the disease to Jordan, and the identification of these earlier cases, marks a significant epidemiological development and suggests that infections may have gone undetected in other countries. What is needed now, says Heymann, is “good old shoe-leather epidemiology; that’s what worked in SARS”. Epidemiologists need to talk to the families and neighbours of any infected people; try to track down everyone who has come into contact with them to look for symptoms and test for the virus; and isolate infected people to try to stop any spread. Researchers including Christian Drosten, director of the Institute of Virology at the University of Bonn Medical Centre in Germany, have moved quickly to develop diagnostic tests to determine whether people or samples are infected with the coronavirus. These tests are now being rolled out by many national health authorities, and Drosten says that a survey in Europe is showing a particularly quick response. Teams from the WHO and the US Centers for Disease Control and V I R O L O G Y

DOI: 10.1038/492166a

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@article{Butler2012ClustersOC, title={Clusters of coronavirus cases put scientists on alert.}, author={Declan Butler}, journal={Nature}, year={2012}, volume={492 7428}, pages={166-7} }