Possible resurgence of H5N1 feared

The United Nations Food and Agriculture Organization warned of a possible resurgence of H5N1 bird flu because of a vaccine-evading strain that recently appeared in Vietnam and China, but other experts disagree with the report.

Some influenza experts said that the FAO statement was not only not surprising, but offered little in the way of information that would suggest an increase in the risk posed by the virus, according to CIDRAP News.

H5N1 has killed poultry in a total of 63 countries since 2003 and, since that time, has caused more than 550 confirmed cases in humans. Of those cases, 331 have resulted in death.

"Wild birds may introduce the virus, but people's actions in poultry production and marketing spread it," FAO Chief Veterinary Officer Juan Lubroth said, CIDRAP News reports.

After reaching a peak in 2006, outbreaks of avian flu declined until mid-2008, when they began to increase in number and scope, probably due to migratory patterns, according to the FAO.

There were 302 outbreaks recorded in the first half of 2008, when the disease began its second round of expansion. Since then, H5N1 has appeared in countries that had been from infection for several years, including Israel, Bulgaria, Romania, Nepal and Mongolia.

"Vietnam's veterinary services are on high alert and reportedly considering a novel, targeted vaccination campaign this fall," the FAO stated, CIDRAP News reports. "Virus circulation in Vietnam poses a direct threat to Cambodia, Thailand and Malaysia as well as endangering the Korean peninsula and Japan further afield. Wild bird migration can also spread the virus to other continents."

An avian health expert from the University of Minnesota in St. Paul, David A. Halvorson, said he saw nothing unexpected in the FAO’s warning.

"This appears to be a continuing situation where the Asian lineage HPAI [highly pathogenic avian influenza] H5N1 virus escapes from an endemic region and causes infection in another area," Halvorson said, according to CIDRAP News. "That spread may come about by poultry movement or wild bird movement."

Halvorson also commented on the growing number of reported outbreaks. He said that countries have varying degrees of incentives and disincentives to report outbreaks and it therefore becomes difficult to accurately understand what is really happening in a given location.

Dr. Michael Olsterholm, another expert from the University of Minnesota, voiced similar concerns about the FAO’s analysis.

"I'm not sure what it means that the number of outbreaks is up this year. We don't know how good the surveillance is," Olsterholm said, CIDRAP News reports. "We all know there's a risk of H5N1 changing and becoming much more lethal again in birds and humans. But there's no data that supports that's happening."