WASHINGTON, Oct. 27, 2006 - The U.S. Departments of Agriculture and Interior today announced final test results, which confirm that no avian influenza virus was found in samples collected earlier this month from wild Northern pintail ducks in Ohio.
The USDA National Veterinary Services Laboratories (NVSL) confirmed that there was no avian influenza present in samples collected from wild Northern pintail ducks in Ottawa County, Ohio. Initial screening results announced on Oct. 14 indicated that H5 and N1 subtypes might be present in the collected samples, but further testing was necessary to confirm the H and N subtypes as well as pathogenicity.
The initial rapid screening tests are highly sensitive and can detect inactive viruses in samples. It is not unexpected to have positive results on an initial screening test and then to have confirmatory testing reveal that no active virus is present in a sample. The initial screening tests performed on the Ohio samples resulted in a weak positive for both H5 and N1. During confirmatory testing, H5 and N1 subtypes were not found; no virus could be grown during the virus isolation test.
To date, USDA and DOI have announced 12 presumptive positive and/or confirmatory test results in six states (MI, MD, PA, MT, IL and OH). As the expanded surveillance of wild birds for highly pathogenic avian influenza increases in the coming months, USDA and DOI expect additional detections of the "North American strain" of low pathogenic H5N1 avian influenza (LPAI H5N1).
Because these LPAI H5N1 detections are common and pose no threat to human health , USDA and DOI are transitioning to a new method of notifying the public. In an effort to maintain transparency, USDA and DOI will post all future suspected LPAI H5N1 detections on the Internet. DOI will maintain a list of all such routine detections as part of the National Highly Pathogenic Avian Influenza Early Detection Data System (HEDDS). The low path H5N1 detection list can be accessed at http://wildlifedisease.nbii.gov/ai/LPAITable.pdf. A link also will be available on USDA’s avian influenza Web page at http://www.usda.gov/birdflu as well as on DOI’s avian influenza bridge page at http://www.doi.gov/issues/avianflu.html
In the event of a presumptive H5N1 test result involving a large number of sick or dead birds, or other circumstances that suggest the possibility of a highly pathogenic virus, USDA and DOI will issue a news release or conduct a technical briefing to notify the media and the public.
Low pathogenic strains of avian influenza occur naturally in wild birds and typically cause only minor sickness or no noticeable signs of disease in birds. These strains are common in the U.S. and around the world. Low pathogenic avian influenza viruses are very different from the more severe highly pathogenic H5N1 circulating in parts of Asia, Europe and Africa. Highly pathogenic strains of avian influenza spread rapidly and are often fatal to chickens and turkeys.
The Departments of Agriculture and Interior are working collaboratively with States and academic institutions to sample wild birds throughout the United States for the presence of highly pathogenic avian influenza.
For more information about the collaborative avian influenza efforts go to www.usda.gov/birdflu, www.doi.gov/issues/avianflu or the U.S. Government's Web site for avian influenza and human pandemic preparedness at www.avianflu.gov.