Wildlife Health Bulletin #06-07
To: Natural Resource/Conservation Managers
From: Leslie Dierauf, Director, USGS National Wildlife Health Center
Title: Low-path Avian Flu H5 and N1 Found in Michigan and Ohio, and Confirmation on Results from Illinois and Montana
Date: October 23, 2006
Low-path Avian Flu H5 and N1 Found in Michigan Green-winged Teal:
The U.S. Department of the Interior (DOI) and Department of Agriculture (USDA) announced on October 20 the detection of H5 and N1 avian influenza subtypes in a sample collected from a green winged teal on Saginaw Bay in Tuscola County, Michigan.
Initial tests confirm that this sample, taken from a wild bird, does not contain the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa. The sample was collected from an apparently healthy bird and initial test results indicate the presence of low pathogenic avian influenza (LPAI) virus, which poses no threat to human health.
Fifty-one bird samples were collected on October 15 as part of an expanded wild bird monitoring program through a partnership between USDA and the Michigan Department of Natural Resources. USDA and DOI are working collaboratively with states to sample wild birds throughout the United States for the presence of highly pathogenic avian influenza (HPAI). Although not a cause for concern, USDA and DOI expect to identify additional cases of common strains of avian influenza in birds.
Of the 51 samples collected, five were sent to USDA's National Veterinary Services Laboratories (NVSL) in Ames, Iowa, for confirmatory testing. One sample tested positive for both H5 and N1 subtypes. However, this does not mean these birds are infected with an H5N1 strain, as it is possible that the sample contained two separate avian influenza viruses, one containing H5 and the other containing N1.
Confirmatory testing underway at NVSL will clarify whether one or more strains of the virus are present and the specific subtype, as well as confirm the pathogenicity. Results are expected within 2 to 3 weeks and will be made public when completed.
Low-path Avian Flu H5 and N1 Found in Ohio Northern Pintails:
On October 14, the USDA and DOI announced detection of H5 and N1 avian influenza subtypes in a sample from an apparently healthy wild Northern pintails in Ottawa County, Ohio. Initial tests confirm that the wild bird sample does not contain the highly pathogenic H5N1 strain.
The samples were collected from birds on October 8 as part of an expanded wild bird monitoring program coordinated through a partnership between USDA and the Ohio Division of Wildlife. Thirty-five samples were collected directly from apparently healthy wild birds and screened for H5 at the Ohio Department of Agriculture Animal Disease Diagnostic Laboratory. Two samples were sent to NVSL in Ames, Iowa, for confirmatory testing; one sample tested positive for both H5 and N1 subtypes. However, this does not confirm that these birds are infected with an H5N1 strain. As stated above, it could be two separate avian influenza viruses, one containing H5 and the other containing N1.
Confirmatory testing is underway at NVSL and results are expected within 1 to 2 weeks.
Illinois Preliminary Low-path Avian Influenza H5 and N1 – Confirmed as H6N2:
On October 17, the NVSL confirmed the presence of H6N2 through virus isolation in five of 11 samples collected from wild green-winged teal in the Rice Lake Conservation Area of Fulton County, Illinois. Initial screening results announced on September 29 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 the presence of many strains of active and inactive viruses in samples. Because these rapid screening tests are highly sensitive, it is common to have positive results for a specific subtype on the initial screen test and yet not be able to isolate a virus of that subtype in the confirmatory test. This was the case for the N1 subtype in the sample that resulted in a weak positive for both H5 and N1 in the initial screen tests. During confirmatory testing, H5 and N1 subtypes were not found; instead, H6 and N2 were found, confirming that the virus is LPAI.
Montana Preliminary Low-path Avian Influenza H5 and N1 – Confirmed as H5N3
On October 7, the NVSL confirmed the presence of low pathogenic H5N3 avian influenza through virus isolation in 2 of 16 samples collected from wild pintails in Cascade County, Montana. Initial screening results announced on September 21 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, and the pathogenicity.
For additional information on avian influenza, please go to:
For information about the federal government’s overall efforts related to avian influenza and human pandemic preparations, go to www.avianflu.gov.