OIE says wild bird deaths from H5N1 may be cyclical

May 21, 2007 (CIDRAP News) – In the first half of 2007, countries reported fewer migratory bird deaths from the H5N1 avian influenza virus, but the virus is still circulating among poultry flocks in several countries, the World Organization for Animal Health (OIE) said today.

The drop in wild and migratory bird deaths could indicate that the disease is nearing the end of a cycle, said Bernard Vallat, director-general of the OIE, in a press release. However, the fact that poultry deaths steadily continue sends an important message, he said: "That shows the international community needs to keep up its high level of prevention and control measures of the disease in animals."

Michael T. Osterholm, PhD, MPH, director of the University of Minnesota Center for Infectious Disease Research and Policy, publisher of the CIDRAP News, said the presence of disease cycles in birds should not be interpreted to mean H5N1 does or doesn't still pose a risk. "Like any other disease, there are ebbs and flows," he said, adding that as birds which build up immunity to the virus die off, the new populations that replace them are vulnerable to avian flu, which then can lead to a surge in wild bird cases.

Disease trends in wild birds will always differ from those seen in domestic birds, because animal health officials have few intervention options. Said Osterholm, "The cycle in wild birds is pretty much on its own."

The OIE said 59 countries have reported H5N1 outbreaks in birds since 2003. Vallat said he was encouraged by the improvements many countries have made in their disease control efforts. "Globally, countries have improved governance on implementation of preventive measures as recommended by the OIE, the FAO [United Nations Food and Agriculture Organization], and the WHO [World Health Organization] to avert the disease," he said in the press release.

Highly pathogenic avian influenza remains endemic in three countries—Indonesia, Nigeria, and Egypt—and continues to appear in previously unaffected countries, according to the OIE press release. In 2007 so far, H5N1 avian influenza has for the first time struck birds in Ghana, Bangladesh, Saudi Arabia, and Britain.

The OIE emphasized the need for global solidarity in the fight to control H5N1 in birds. "A single failing country, and the whole world is at risk of infection," the organization said.

Juan Lubroth, senior officer of the FAO's infectious disease unit, said in a Feb 20 FAOAIDE News report that transparency around disease outbreaks, direct involvement of farmers in surveillance and reporting, and compensation are key to global efforts to control the disease. He said the lower number of bird outbreaks in 2007 is partly due to less migration by wild birds from Asia to Europe last fall. However, the FAO report said poultry trade and the transport of live birds could still spread the virus, which requires strong vigilance.

See also:

May 21 OIE press release
http://web.oie.int/eng/press/en_070521.htm

Feb 20 FAOAIDE news report

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