Just one further HPAI outbreak was added to the official count from the USDA Animal and Plant Health Inspection Service (APHIS) on 14 May:

• Iowa, Lyon county - 275,000 commercial chickens.

The cause has been confirmed as the H5N2 subtype of highly pathogenic avian influenza virus of mixed Eurasian and American origin.

The report does not give the migratory bird flyway involved; all previous outbreaks in Iowa have been linked to the Mississippi flyway.

One new outbreaks in Minnesota

The Minnesota Board of Animal Health has announced one new presumptive virus-positive flocks in the state:

• Kandiyohi 33 - commercial turkeys (number pending)

This brings the state totals to more than 5.76 million poultry affected on 88 farms in 21 counties.

Minnesota state lawmakers have approved $20 million to help farmers with loans and state agencies trying to contain the virus, reports CBS Local.

Lawmakers from some of the hardest hit areas of the state say the challenge here is figuring out how to stop the spread of the virus.

The State Fair is cancelling all bird exhibits this year as a precaution, CBS Local added.

On 16 May, Star Tribune reported that bird flu had struck another farm belonging to Rembrandt Enterprises farm, marking the state’s single largest outbreak of the deadly virus. Two million egg-laying chickens will be destroyed over the next four weeks at the company’s Renville operation, officials said.

One barn holding around 200,000 birds was infected but the entire flock will be killed as a precaution.

Chickens at the farm have tested 'presumptive positive' for the disease “despite the herculean efforts of Rembrandt’s employees to keep our facilities virus-fee,” said Jonathan Spurway, the company’s vice president of marketing.

According to Star Tribune, Rembrandt Enterprises is one of the nation’s largest egg producers and it suffered an outbreak in its facility in Rembrandt, Iowa, on 1 May.

Testing to start for avian flu vaccine

An Iowa biotech firm is expected to begin testing as soon as next week a vaccine that could protect poultry from the avian flu virus that has resulted in the deaths of millions of birds, reports Des Moines Register.

Harrisvaccines will test the vaccine with the Agriculture Department at its National Veterinary Services Laboratories in Ames – first on turkeys, with a second test on chickens and ducks soon after at the government's Southeast Poultry Research Laboratory in Georgia.

No new outbreaks suspected in Iowa

Iowa Department of Agriculture and Land Stewardship (IDALS) has reported no new probable cases of HPAI and so the state total remains at 52.

No new outbreaks in Nebraska

The Nebraska Department of Agriculture has not reported any new confirmed or suspected cases of H5N2 HPAI and so the state total remains at two - in adjacent commercial layer flocks owned and operated by the same producer.

No new outbreaks in South Dakota

South Dakota Animal Industry Board has reported no new confirmed or suspected cases of H5N2 HPAI and so the state total remains at nine, affecting 1,650,900 birds.

No new outbreaks in Wisconsin

Wisconsin Department of Agriculture, Trade and Consumer Protection reported no new cases of H5 HPAI on 14 May.

The total number of birds affected is over 1.76 million, comprising more than 1.11 million chickens and 652,000 turkeys (41,760 hatching eggs).

Overview of high-path avian flu outbreaks in US poultry

The following information is based on published USDA APHIS outbreak reports:

• The latest cases bring the total number of confirmed high-path avian flu outbreaks since December 2014 to 163.
• Outbreaks have occurred in poultry in 15 states.
• Three of the early outbreaks were caused by the H5N8 sub-type of the virus but in almost all those since mid-February 2015, an H5N2 variant of mixed Eurasian and American origin has been confirmed.
• The majority of outbreaks have been in commercial turkeys (116); 30 have been in commercial chickens, one in a mixed commercial flock and 16 in backyard flocks.
• The number of poultry known to have been affected by these outbreaks now exceeds 33.79 million. This figure includes more than 27.80 million commercial chickens and 5.91 million commercial turkeys as well as 7,173 backyard poultry.
• The disease has also affected seven captive wild birds at five locations.