Highly pathogenic H5N1 avian influenza has returned to commercial poultry in the northern United States. Since 1 September the US Department of Agriculture's Animal and Plant Health Inspection Service has confirmed seven detections in commercial operations across North Dakota, South Dakota, Minnesota and Idaho, according to the University of Minnesota's CIDRAP tally.

The affected sites are a turkey facility of 29,800 birds in Wright County, Minnesota; turkey farms of 61,300 birds in McPherson County and 43,800 in Turner County, South Dakota; a 41,600-bird commercial site in LaMoure County, North Dakota; and a commercial breeding operation of 30,200 birds in Edmunds County, South Dakota. Idaho reported two backyard outbreaks, in Canyon and Gem counties.

Over the past 30 days eight commercial and six backyard flocks have been infected, affecting about 360,000 birds.

Separately, two more dairy herds in Idaho have been confirmed infected. Idaho and Texas have together reported the virus in five herds in the past 30 days, and there have been 88 H5N1 detections in cattle nationwide so far this year.

The detections fall in the weeks when turkeys are being grown for the year-end market; for the dairy sector the Idaho cases show the cattle strain has not been cleared from western herds.

Source: The Poultry Site