The arrival of spring means that your animals want to go outside, not just dogs and cats but the increasing number of backyard chickens that are tired of being literally cooped up.

Yet there’s a reason to think twice: Highly pathogenic avian flu, which is not only killing birds but starting to kill mammals, including pets.

“It’s here, it’s absolutely here,” said State Veterinarian Stephen Crawford. “We continue to see it in wild birds when they are surveyed – waterbirds, shore birds, raptors, but especially waterbirds.”

Since this virus showed up in the U.S. in January of last year, more than 58 million chickens, turkeys and other poultry have died from the disease or been killed as part of an “emergency depopulation” of a farm to halt its spread. This carnage has contributed to a sharp rise in the price of eggs and occasional shortages of chicken meat.

The virus has also caused die-offs of wild birds, from geese to bald eagles. But birds aren’t the only concern.

Some mammals are also at risk of this strain. While the most affected so far are sea mammals like seals, presumably because they live among virus-carrying sea birds like gulls, there have been three known cases in which pet cats have died from the disease contracted by eating wild birds.

“The risk is from your dogs and cats consuming infected wildlife. Always keep them away from sick or injured wildlife, or really any wildlife,” said Crawford. “That’s the most important message you can get across.”

A different strain

The latest avian-flu outbreak is called H5N1 after mutations in proteins on its surface. It is a different mutation than an avian flu outbreak in 2015 that resulted in the death of more than 5 million poultry in the U.S. but had no major crossover into mammals. That outbreak never showed up in New Hampshire, Crawford said.

The H5N1 strain appears to have originated in China and showed up in the U.S. in January of last year, arriving here from Europe. It has since spread to South America. It is almost always fatal, hence the term “highly pathogenic” to differentiate it from flu viruses that cause sickness but rarely kill their host.

As well as alarming poultry farms, its spread has raised concern about the effect on wild bird populations, especially those that are already endangered. About 150 different species of birds in the U.S. have been found to carry the H5N1 virus. Of particular concern are ducks and geese.

It is “well-adapted to spread in waterfowl. It doesn’t kill them all,” saId Dr. Nicola Hill of the University of Massachusetts-Boston during a recent SciLinewebinar sponsored by the American Association for the Advancement of Science. “Ducks are great hosts. They swim and fly; there are multiple modes of spreading it.”

Wild birds can spread the virus to chickens, turkeys and other free-range domestic poultry through direct contact or when poultry encounter their feces on the ground or in water.

New Hampshire has seen three known cases of H5N1 in domestic poultry, the most recent in January, but no major outbreaks, Crawford said.

Of particular concern is how H5N1 has evolved to spread to mammals, a recent development seen most dramatically in the March deaths of thousands of sea lions on the coast of Peru. While there is no evidence yet that the virus is spreading from mammal to mammal, there is no guarantee that the virus won’t evolve in that direction.

Worldwide, there have been a few cases of human infection, most related to open-air markets where live poultry is sold and slaughtered on site. None were in the U.S.

Avoiding contamination is key

There is no vaccine against the virus, and although research is ongoing, officials say that realistically it would not be possible to vaccinate the world’s huge population of domestic birds, which number in the hundreds of millions, if not billions. As a result, there is concern that this virus will become endemic in a highly pathogenic form.

Treatment is often difficult, so avoiding contamination is the best defense through practices known overall as biosecurity. That mostly involves limiting birds’ contact with people, animals or wild birds and avoiding situations where contamination might be carried from one building to another on clothing or boots.

“It’s important to keep visitors away from your birds, in particular visitors who own their own birds,” said Crawford.

“We follow the recommendations of the NH State veterinarian and USDA. Both are currently recommending that poultry be housed in a manner that isolates them from wild birds, particularly migratory waterfowl. Poultry owners are also advised to monitor their bird’s health and immediately isolate any sick birds,” wrote Mary Davis, a field specialist with 4-H animal science for UNH Cooperative Extension, in response to a Monitor query.

For commercial poultry operations Crawford suggested having dedicated sets of boots or clothing that can be left in each poultry area, to minimize spread of any disease. Quickly cleaning spills of chicken feed to reduce the attraction of wild animals is important, as is ventilation and wash stations of employees or even vehicles.

The AAAS webinar noted that in places where the virus has been found, free-range certification – important for farms selling eggs or meat in organic markets – can be maintained even if birds must be kept indoors for a time.

The big concern is exposure to wild waterfowl like ducks, which seem to be acting as a reservoir for the virus, said Crawford.

“If your birds are outdoors, allowed to roam around, you should probably be more thoughtful about how close they are to open water bodies,” said Crawford. “That’s a fairly consistent risk factor in a lot of these small flocks that have had problems – a water body within a half-mile or so.”

The state will conduct tests of chickens and other domestic non-waterfowl poultry at the owners request, “as often as possible at no charge” thanks to a U.S. Department of Agriculture fund. They collect blood to test for influenza and salmonella from birds that are not sick and test it at the state veterinary diagnostic lab in Durham. For sick birds they’ll take swabs and send them to a national lab in Connecticut, since the Durham lab doesn’t have the proper PCR equipment for those tests yet. “We’re working on it,” Crawford said.

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