Avian Influenza

Since December 2003, highly pathogenic H5N1 avian influenza viruses have swept through poultry populations across Asia and parts of Europe. The outbreaks are historically unprecedented in scale and geographical spread. Their economic impact on the agricultural sector of the affected countries has been large. From December 2003 to mid-July 2005, outbreaks of avian influenza A(H5N1) in poultry occurred in nine countries (Cambodia, China, Indonesia, Japan, the Republic of Korea, the Lao People's Democratic Republic, Malaysia, Thailand and Viet Nam). Since late July 2005, outbreaks in domestic poultry as well as wild birds have been reported in the Russian Federation, Kazakhstan, Romania, Mongolia, Turkey and Croatia. In addition, during this period outbreaks in poultry have increased again in Indonesia, Thailand, Viet Nam and China.

Three contiguous WHO regions – Western Pacific, South-East Asia and Europe – now have H5N1 activity in wild fowl and poultry stocks. Evidence shows that the H5N1 virus is most likely endemic in many parts of Asia. It has established an ecological niche in poultry, making it extremely difficult to control outbreaks. Outbreaks have recurred despite aggressive control measures, including the culling of more than 140 million poultry as of September 2005.

Human cases, with an overall fatality rate around 50%, have been reported in Cambodia, Indonesia, Thailand and Viet Nam. Almost all human infections can be linked to contact with infected poultry, but isolated instances of inefficient human-to-human transmission may have occurred in Viet Nam in 2004, and possibly in Thailand and Indonesia. Influenza viruses are genetically unstable and their behaviour cannot be predicted. The risk of further human cases persists, as do opportunities for a human pandemic strain of the virus to emerge. For these reasons, the current outbreaks of influenza A(H5N1) in poultry and humans in Asia, has moved the world closer to a pandemic than any time since 1968, when the last such event occurred.

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Fact sheets

News and press releases

11 June 2008
WHO to review its work in the Western Pacific Region
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07 December 2007
Lao PDR tests its pandemic preparedness
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28 March 2007
Rapid-containment exercise will test plans to avert an influenza pandemic
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Relevant publications and documents

WHO Global Influenza Preparedness Plan
The WHO global influenza preparedness plan has been prepared to assist WHO Member States and those responsible for public health, medical and emergency preparedness to respond to threats and occurrences of pandemic influenza

WHO Influenza Pandemic Preparedness Checklist
November 2004 version

Influenza pandemic preparedness and response

Stop the Spread - Measures to Stop the Spread of Highly Pathogenic Bird Flu at its Source
This document outlines strategies to minimise the disease in the production, distribution, processing and marketing of poultry, thereby reducing the risk to human health from Avian Influenza.The strategies where developed during the FAO/OIE/WHO Consultation on Avian Influenza and Human Health: Risk Reduction Measures in Producing, Marketing, and Living with Animals in Asia, held in Kuala Lumpur, Malaysia, from 4 to 6 July 2005 (full meeting report is below).