Surveillance programme finds avian influenza in the US
The US Departments of Agriculture and Interior today announced that
routine surveillance has indicated the presence of H5 and N1 avian influenza
subtypes in samples from two wild mute swans in
Testing has ruled out the possibility of this being the highly pathogenic
H5N1 strain that has spread through birds in Asia, Europe and Africa. Test
results thus far indicate this is low pathogenicity avian
influenza, which poses no threat to human health.
The swans were sampled as part of the expanded avian influenza surveillance
programme. They were showing no signs of sickness, which suggests that this is
low pathogenicity avian influenza. Additionally, genetic analysis of the virus
conducted at USDA's National
Veterinary Services laboratories (NVSL) in Ames, Iowa, suggests that it is
similar to a low pathogenicity strain that has been found in North America.
"This is not the highly pathogenic avian influenza virus that has spread
through other parts of the world," said Dr Ron DeHaven, chief of the Animal and Plant Health
Inspection Service at the Agriculture Department. "We do not believe that it
represents a risk to human health."
Because federal and state game rangers and university ornithologists are
testing thousands more birds since Congress approved $29 million for expanded
bird flu screening, Dr DeHaven said it was 'no surprise' that the virus had been
It is possible that these birds were not infected with an H5N1 strain, but
instead with two separate avian influenza viruses, one containing H5 and the
other containing N1. The confirmatory testing underway at NVSL will clarify
whether one or more strains of the virus are present, the specific subtype, as
well as pathogenicity. These results are expected within two weeks and will be
made public when completed.
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