Avian Influenza (H5N1)

Avian Influenza Photo
In efforts to prevent further spread of H5N1, wild bird species are also being monitored for the disease.
©Angela Yang

Some avian influenza viruses are relatively harmless, but others are deadly and highly contagious. In the 1918 flu epidemic, a strain of avian influenza killed an estimated 40 million people around the world. In the mid-1990s, a strain emerged in Asia that was lethal to poultry, humans, and wildlife. That latter strain—called highly pathogenic avian influenza (H5N1), or HPAI H5N1—moves from region to region mainly via the poultry trade and in some cases through the movement of wild birds. Authorities have spent billions of dollars and destroyed billions of domestic birds in efforts to curb the virus’s spread and ensure the safety of the food supply. To date, the virus has killed more than 260 people.


Infected humans have typically acquired the virus through close contact with infected birds. So far, there has only been limited human-to-human transmission of HPAI H5N1. However, should the virus develop the ability to move easily between humans, a pandemic could result. Containing the virus to lessen the opportunities for transmission and mutation is vital for protecting human, livestock, and wildlife populations.


  • Expand the capacity for field monitoring of wild birds globally
  • Improve the understanding of viral strains and the transmission of influenza viruses in wild birds
  • Disseminate avian influenza information to all levels of governments, international organizations, the private sector, and the general public.

What WCS is Doing

In 2005, HPAI H5N1 killed several thousand wild birds in central China--the first time the virus had significantly spread within a wild animal population. Until then, spread of the virus had been limited to poultry populations in Asia. Subsequent WCS research found the virus in whooper swans in Mongolia. With expansion of the disease in the poultry sector and its spread to wild bird populations, the need to monitor wild bird populations and to provide the best data possible to minimize the risk of disease spread became evident.

Consequently, WCS-Global Health launched GAINS (the Global Avian Influenza Network for Surveillance). With few exceptions, current global disease surveillance efforts focus on humans and domestic livestock. Funded primarily by USAID and the Centers for Disease Control and Prevention (CDC), GAINS fills the wildlife “gap” by conducting bird surveys, collecting thousands of biological samples, and training more than 2,000 people around the world in bird identification and sampling techniques. Working in more than 30 countries, GAINS has developed an open-access, data-sharing system that holds millions of data points.

From the Newsroom

Which Way Will This Bird Flu Fly?May 16, 2013

With the emergence of a new zoonotic disease, H7N9, WCS’s Bird Coordinator Steve Zack reflects on the increasing mingling of birds, humans, and domesticated animals across the globe, and the need for improved management practices by poultry farms and markets.

Mapping the Illegal Wildlife TradeFebruary 17, 2012

A new collaboration between WCS and Children's Hospital Boston uses media reports to help track wildlife trade and reduce its associated disease risks.

Serendipity in SumatraJune 1, 2010

WCS field veterinarians tracking avian influenza catch a glimpse into the life of a little-known bird, Nordmann's greenshank, as it flies between the Russian seacoast and the beaches of Sumatra.

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