Research News

Emerging epidemiology of H7N9 avian flu

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f2717 (Published 01 May 2013) Cite this as: BMJ 2013;346:f2717

Enhanced surveillance for the new H7N9 avian flu identified 82 confirmed cases in six areas of China between 25 March and 17 April 2013. Seventeen infected people died of respiratory complications or multiorgan failure a median of 11 days after the first signs of illness, according to the first epidemiological study of the outbreak. Sixty others were still critically ill on 17 April.

Most of those affected were older (median age 63 years, interquartile range 50-73), men (60/82), and had a history of recent exposure to live animals (59/77), usually chickens or ducks. Fifty four of the 71 cases with data available had underlying medical conditions, most commonly hypertension, diabetes, or heart disease. Only two patients were under 5 years old and both had mild upper respiratory symptoms only. Researchers identified three clusters of cases within families and can’t rule out human to human transmission.

Infected poultry is the most likely source of the outbreak, and public health authorities should consider early control measures, such as disinfecting or even closing live poultry markets, while we wait for further confirmation, say the researchers. A separate study reported close genetic similarities between H7N9 viruses isolated from cases and from local chickens.

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Cite this as: BMJ 2013;346:f2717