H5N1 Bird Flu in Illinois
Recombinomics Commentary
September 29, 2006
The U.S. Department of Agriculture (USDA) and Department of the Interior (DOI) today announced a detection of the H5 and N1 avian influenza subtypes in samples from wild, migratory Green-winged Teals in Illinois. Initial tests confirm that these wild duck samples do not contain the highly pathogenic H5N1 strain that has spread through birds in Asia, Europe and Africa.
The bird samples were collected on Sept. 24 in the Rice Lake Conservation Area of Fulton County, Illinois, through a partnership between USDA and the Illinois Department of Natural Resources as part of an expanded wild bird monitoring program.
Eleven samples were collected directly from the ducks. Of those samples, a pool of five samples tested positive for H5 and were sent to USDA's National Veterinary Services Laboratories (NVSL) in Ames, Iowa, for confirmatory testing. One of the five samples screened by NVSL tested positive for both H5 and N1.
The above comments strongly suggest H5N1 bird flu has been found in Illinois. The announcement is similar to earlier announcements of H5N1 in mute swans in southern Michigan, mallards in Maryland and Pennsylvania, and Northern pintail in Montana. In all cases, cloning yielded one or more H5N1 isolates.
In each case low path North American strains were isolated. It remains unclear if additional H5 serotypes were detected. Last year Canada found H5N1, H5N2, H5N3, and H5N9 in various provinces across southern Canada. This year Canada has detected H5N2 and H5N6 and overall results mirrored last year’s results, but numbers, locations, and serotypes have not been delineated other than the one report from Quebec.
The data from both country suggests H5 has been widespread in North America since August of 2005, and this year H5N1 is common across the northern regions of the lower 48 states in the US, as well as southern Canada.
Thus far, only sequences from one H5N2 in British Columbia collected in August 2005. That sequence had some Canadian swine and Asian polymorphisms, signaling evolution via recombination.
In addition, H5 was detected in a dead goose on Prince Edward Island. The other three dead geese were not tested, but all four died suddenly after showing symptoms found in H5N1 infections of waterfowl by the high path Qinghai strain. These results strongly suggest the Qinghai strain of H5N1 has already migrated to North America. Low path H5N1 rarely kills waterfowl.
Wild birds are frequently infected with multiple strains. Cloned isolates listed for sequencing by OSU frequently have serotypes that do not match the initial serotype for the un-cloned samples. Thus, there are several ways that low path H5N1 can mask the presence of high path H5N1.
Sequence analysis however, can frequently detect prior interactions and recombination between high and low path H5N1. Therefore, sequences from the 2005 and 2006 isolates should be released. OSU has sent earlier samples for sequencing under in NIAID Influenza Sequencing Project.
However, the most recent table of submitted samples does not include any recent H5N1 collections.
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