U.S. Wild-Bird Survey Finds No Evidence of H5N1
WASHINGTON -- Tests on nearly 75,000 wild ducks, gulls and other birds have turned up no sign of dangerous H5N1 avian influenza in the United States, a federal agency said Thursday.
"The program was unprecedented in scope in terms of the range of species of birds sampled, which included waterfowl, shorebirds, gulls and terns, among others," Hon Ip of the U.S. Geological Survey said in an e-mail posted to an infectious-disease message group.
"As of today, the testing of over 74,506 samples in wild birds from across the United States has been completed, and no highly pathogenic avian influenza viruses have been found," said Ip, who works at the USGS National Wildlife Health Center in Madison, Wisconsin.
The tests did turn up several samples of a low-pathogenic H5N1 virus, which is not particularly dangerous to either birds or to people, the USGS reports on its Web site at http://wildlifedisease.nbii.gov/ai/.
Canada has run similar surveys and found no dangerous bird flu.
Birds infected with low-pathogenic H5N1 were found in states including Delaware, Illinois, Michigan, Pennsylvania and Maryland. This virus is apparently not dangerous to the birds, although Ip said he wanted to study infected birds to see if it has subtler effects on their ability to survive and migrate.
USGS, the U.S. Fish and Wildlife Service and experts from other federal agencies have been testing birds since 2005 for H5N1 avian influenza, concentrating on Alaska but looking in all regions.
Experts expect the virus to eventually arrive in North American birds, carried by migrating birds as it has been to various parts of Asia.
This year, outbreaks in birds have caused concern in Japan, South Korea, Vietnam, Turkey, Pakistan, Hungary and in Nigeria, which reported its first human death earlier this month.
The disease continues to kill people and poultry in Indonesia, as well. WHO says there have been 273 human cases worldwide and 166 deaths since 2003. More than 200 million birds have died or been slaughtered.
The virus can be carried by both wild birds and by the commercial poultry trade. Ip said it was important to get hard data on when the virus is spread by wild birds and when it is spread by other means -- from truck tires to infected feathers.
There are dozens of different kinds of avian influenza. The highly pathogenic H5N1 is particularly deadly to chickens and is thus a threat to the poultry industry.
H5N1 poses an additional threat to people because it has has shown a tendency to mutate. It could change into a form easily transmitted from one person to another, experts say, in which case it would rapidly sweep around the globe.