Commentary
H7N3 in Arkansas Raises Surveillance Concerns
Recombinomics Commentary 12:50
June 4, 2008
Jones speculated that migratory geese brought this low pathogenic strain to Northwest Arkansas, and it was spread to the breeder hens by accident.
“Typically these things happen in spring and fall, when we get water fowl migration. There’s been a lot of water fowl that have come through,” Jones said.
The Tyson Foods breeder flock tested positive for the H7N3 antibodies found in the blood stream, but tested negative for actually having avian flu, Fitch said.
The above comments describe the detection of H7N3 antibodies in poultry flocks in Arkansas. However, the reports also highlight surveillance failures of finding H7N3 in wild birds prior to the outbreak, as well as H7N3 virus prior to the development of antibodies in the affected flocks.
Recent scientific reports have highlighted concerns of H7 infections in humans. The receptor binding domain activity of A/New York/107/2003(H7N2) was increased for human receptors and decreased for avian receptors. Moreover, the virus was transmitted ferret to ferret to produce respiratory disease. HA related to the above isolate is widespread in domestic poultry in the northeast, but also not found in wild birds.
A recent report has raised questions about mismatched primers used to detect H7 in wild birds. These primers do not match the H7 in the birds, and therefore produce false negatives. It is unclear if this flawed approach contributed to the failure to find H7 in the hens with H7N3 antibodies.
In addition to the H7N2 case in New York, almost exactly one year ago England reported H7N2 in small holdings that were linked to H7N2 infections in humans. Although only four patients were confirmed, many more had symptoms and some were hospitalized.
Similarly, the H7N7 outbreak in The Netherlands in 2003 was linked to PCR positive tests in 89 cullers. Most had mild disease, including conjunctivitis. However, testing for H7 antibodies identified over 1000 positive contacts, demonstrating the efficient human to human transmission.
Therefore, the possibility of human infections in Arkansas is real, but unlikely to be reported because of a fatally flawed surveillance program in North America, which has failed tom find H5N1 in wild birds, although PCR confirmed H5 was reported in a dead gosling (in association with the death of all 3 goslings) on Prince Edward Island.
These serious surveillance failures remain causes of concern.
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