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H5 in Dead Duck in Lakeport California
September 30, 2006
The City Council will soon discuss banning any feeding of ducks or waterfowl at Library Park. This comes after another dead duck was found last weekend at Library Park and one of the ducks tested previously by the California Department of Fish and Game has tested positive for H5 avian influenza.
"In this particular case, we had a positive hit for avian influenza and the subtype is H5 category," said Retallack.
The above comments indicate H5 has been detected in a dead duck at Library Park in Lakeport, CA. Last month dead ducks were tested and were said to have died from avian botulism. However, the presence of H5 raises additional concerns.
Test results have not been announced by the National Veterinary Services Laboratories (NVSL) in Ames, IA. In the past they have announced the detection of H5N1 in mute swans in Michigan, mallards in Maryland and Pennsylvania, Northern pintail in Montana, and Green-winged Teals in Illinois. These isolates have been characterized as low path and the North American strain based on sequence data and in some instances, followed up with a pathologenicity index.
However, the numerical result of the pathogenicity test has not been disclosed. Moreover, no sequence data has been released.
H5N1 is problematic because wild birds are frequently infected wsith multiple strains, and the strain that grows out in chicken eggs in the testing lab frequently does not match the serotype of the initial test on the uncloned samples. In addition, the various serotypes detected have not been released. Many sampes have been positive for H5, but negative for N1.
The distribution of H5 serotypes remains unclear. This year Quebec has reported H5N2 and H5N6. Last year Canada reported H5N1, H5N2, H5N3, and H5N9. However, all of these earlier reports were from healthy birds tested under a surveillance program. In additiona H5 was detcted on a live market in New Jersey, but the serotype was withheld, and the manadtory OIE report was not filed.
The only dead birds reported to be positive were from four dead geese on a farm on Prince Edward Island (PEI). Those geese suddenly died after neurological symptoms. One was tested and was H5 positive, but virus was not isolated and sequence data was not generated from the insert from the PCR test. The size of the insert was withheld and an OIE report was not filed.
The Qinghai strain of H5N1 produces sudden death in waterfowl following neurological symptoms. Neurological problems are also associated with botulism poisoning, so the diagnosis of botulism poisoning in H5 positive dead waterfowl is cause for concern.
More information on the number of dead ducks, as well as the serotype and sequence of the H5 detected, would be useful.