New cases of Eurasian H5 Highly Pathogenic Avian Influenza (HPAI) were detected in domestic flocks in Michigan, Maine and Delaware in recent days, as the bird flu continues to spread in North America and around the world.
On Thursday, an outbreak of HPAI was confirmed by the Michigan Department of Agriculture and Rural Development (MDARD) in a non-commercial backyard flock in Kalamazoo Country, Michigan. Several birds in the flock died and others showed signs of illness before the outbreak was confirmed.
“MDARD is always preparing for situations like this when they arise, which is why we were able to take quick action to contain this disease and help protect against its spread,” said MDARD Director Gary McDowell. “At this time, this is an isolated case. There is no threat to public health or food safety. We do not anticipate any disruptions to supply chains across our state. As this situation develops, we will continue to work with our partners at local and federal levels to best mitigate spread and provide outreach."
The birds in the affected flock have been euthanized and the premises is under quarantine. State health officials called on poultry owners to increase biosecurity measures and keep wild birds away from their flocks.
In New Castle County, Delaware, an outbreak of HPAI was confirmed in a commercial poultry flock.
Two outbreaks of avian influenza have been confirmed in the past week in domestic flocks in Maine, as well. One outbreak was detected in Knox County, while another outbreak was detected shortly afterwards in a flock located about three kilometers away.
The United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) stated that it is working closely with state animal health officials on a joint incident response.
The first confirmed case of Highly Pathogenic Avian Influenza (HPAI) in a US commercial flock since 2020 was detected in a turkey flock in Indiana earlier this month. The flock was infected with the H5N1 subtype, the same strain detected in mid-January in wild birds in North Carolina when the first cases of HPAI this season were detected in the States.
The first case of H5N1 in North America this season was detected in Newfoundland and Labrador in late December. Since then, the virus has spread to other locations in Canada and the US.
As of Saturday, nearly 300 wild birds in South and North Carolina, Virginia, Maryland, Georgia, Connecticut, New Hampshire, Delaware, Alabama, Kentucky, Maine, New Jersey and Florida had been found to be infected with Eurasian H5 HPAI, with a number of cases specified as H5N1.
On Tuesday, the US Centers for Disease Control (CDC) stressed that the current risk to the general public's health from HPAI in the US is low, adding that those who are exposed more to birds, such as poultry workers, may have a higher risk of infection.
HPAI can be carried by wild birds without causing symptoms but can cause illness and death in domestic poultry. Human infections can occur after close contact with infected birds but are rare. No human infections with HPAI have ever been detected in the US.
Some 864 human infections and 456 deaths with the H5N1 subtype have been reported in 19 countries since 2003. The latest human infection was a man who owned ducks in the UK; he recovered from the virus.
A large number of bird flu outbreaks have been reported throughout Europe, Africa and Asia in recent weeks and months, mostly due to the H5N1 subtype, which comes from the H5 lineage, according to the World Organization for Animal Health (OIE). The organization warned that a further increase in outbreaks is expected in the coming months.
According to the Food and Agriculture Organization of the UN (FAO), 935 outbreaks of HPAI have been detected in animals since January 26, 2022. 10 new cases in humans were reported in China, as well.
14 million cases of avian influenza were reported in birds in 2021, more than the previous five years combined, according to figures obtained from the OIE by The Telegraph. 61.4 million birds died either due to the virus or of being culled to prevent its spread.
Scientists warned in The Telegraph report that the increase in outbreaks could help the virus evolve to spread between humans.
The OIE has urged countries to increase surveillance for HPAI outbreaks, as the virus has been reported in over 40 countries since July.
The H5N1-6 and H5N8 subtypes of HPAI are circulating in bird and poultry populations across the globe, sparking concern at OIE, which called this an “unprecedented genetic variability of subtypes... creating an epidemiologically challenging landscape.”
Last month, OIE Director General Monique Eloit told Reuters that "this time, the situation is more difficult and more risky because we see more variants emerge, which make them harder to follow."
"Eventually, the risk is that [the virus] mutates or that it mixes with a human flu virus that can be transmitted between humans then suddenly it takes on a new dimension," she said.