U.S. efforts to monitor H5N1 could easily miss entry of the virus into North America

Dec 13 2007

A University of Kansas investigator closely following the spread of the avian influenza known as H5N1 said that U.S. government monitoring efforts easily could miss the entry of the virus into North America.

A. Townsend Peterson, University Distinguished Professor of Ecology and Evolutionary Biology and senior curator in the Natural History Museum and Biodiversity Research Center, directs teams of scientists who travel from Kansas to far-flung corners of the globe to map the spread of avian flu and other pathogens.

Peterson said the governmental scheme to detect the arrival of H5N1 in North America — the Highly Pathogenic Avian Influenza Early Detection System — overemphasizes testing of wild water birds in Alaska while neglecting other possible “entry pathways” from Eurasia.

“If you take a careful look at bird migration in North America, you probably wouldn't want to, excuse the pun, ‘put all your eggs in one basket',” said Peterson.

The KU researcher said that the Alaskan focus of the program is sensible for monitoring a set of wild Asian birds that spend winter in Asia and sometimes summer in Alaska. But other birds possibly carrying the avian influenza could be overlooked.

“There's another component of birds which spend the winter in America,” Peterson said. “They migrate north in the summer and basically consider western Siberia to be eastern Alaska. That component of birds migrates deep into the Americas, doesn't really stop in Alaska at all, and would be missed by the current monitoring plan.”

According to Peterson, a more effective system to detect the appearance of H5N1 would track wild birds all along the Atlantic and Pacific “flyways” of North America.

“I'm essentially suggesting that we should be considering the entire coastal regions and that the monitoring scheme should be much more based on hard data instead of supposition and just eyeballing the situation,” said Peterson.

Peterson's team published initial results of its research on the official H5N1 tracking program earlier this year in PLoS ONE , a peer-reviewed science journal.

As of this month, government surveillance remains focused on Alaska: According to the detection system, it sampled 11,819 wild birds in that state, compared with 4,054 birds in California, the second-highest state total. No highly pathogenic H5N1 virus has been found in any of these samples.

Peterson said global efforts to track the avian flu also exaggerate the role of wild waterfowl, such as ducks and geese.

Early research showed a higher percentage of these birds contained the H5N1 virus, with lower rates among land birds. “But that seems to have evolved into the idea that only water birds are the reservoir of avian flu,” Peterson said. “As near as I can tell, there are no data behind that. It's just that prevalances are higher. What gets forgotten is that numbers of waterfowl are lower. So, how many bird-fulls of virus are out there in the world flying around? It could easily be more land birds than water birds.”

These gaps in surveillance plans could slow the response to a serious public health risk. According to the World Health Organization, in 2007 there have been 49 human fatalities from H5N1 reported worldwide, out of 74 confirmed cases.

“It has every possibility of turning up in North America, but it hasn't essentially gotten in the door yet, that we know of,” Peterson said. “These are rare events and it can take time. But I see no reason why anybody would believe that it can't happen. If it gets to North America, it's not going to be a terrible plague or anything. But it increases the probability of evolving new virus strains that could turn into something much more dangerous.”