More H5N1 in the US: low-pathogenic strain suspected
The H5N1 bird flu virus has been discovered in two locations in the
US, but according to federal officials it is the low-pathogenic strain found
previously in North America, not the deadly Asian
Both cases involved mallards, or wild ducks.
In the most recent discovery of the virus, ducks sampled on 28 August in
Pennsylvania tested positive for the low-grade strain of H5N1.
The other case occurred in Maryland, where faecal samples collected by
University researchers from wild birds on 2 August tested positive for the
The US Department of Agriculture (USDA)
officials said that in both cases the ducks appeared to be healthy, which would
further suggest they were not carrying the high-pathogenic strain of the H5N1 avian
The results of confirmatory tests should be available in two weeks, officials
from the Agriculture and Interior Departments said.
Veterinary expert Dr Sherrill Davison says the discovery of a low-pathogenic
bird flu strain is no cause for alarm.
"A North American strain of avian influenza is unrelated to the Asian H5N1
highly pathogenic virus that has caused so much trouble overseas," she said.
"This finding reminds us of the continuing need for flock monitoring and
biosecurity on poultry farms, but by itself is no threat to the commercial
The low-grade strain of H5N1 has been found many times in North American wild
birds and poses no threat to people, but some commentators expect the deadlier
strain to reach the continent this year.
However, the USDA fears that the distinction will be unclear to consumers,
who may stop eating poultry meat and eggs. The Department has released an updated fact sheet outlining the differences between high- and
low-pathogenic strains of bird flu, to help clarify the issue.
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