Authorities in Hawaii are warning residents who attended a local pet fair to watch for symptoms of avian influenza after a local flock of ducks and other birds tested positive for the H5N1 virus that has fueled a global outbreak of infections.

Officials suspect wild migrating birds are likely to blame for the first known infection of a flock in Hawaii, which had been the last state in the country with no reported cases in poultry or wild birds during the current outbreak. 

Sequencing done by the U.S. Department of Agriculture’s national lab in Iowa confirmed the infection, federal officials announced Monday. 

The specific genotype of the virus that infected the birds is known as A3, said Lyndsay Cole, a spokesperson for the federal Animal Plant Health Inspection Services. 

This is different from the B3.13 genotype that has been fueling this year’s unprecedented outbreak on dairy and poultry farms and suggests the virus spilled over into the flock in Hawaii from migrating wild birds.

Investigators have not turned up any links so far between the flock and imported animals or travel, a spokesperson for Hawaii’s Agriculture Department said. The island has “strict importing regulations for birds and other animals,” the spokesperson said.

All the infected birds were housed at the same site, though investigations are ongoing to root out other potential cases. The birds were also not symptomatic until several days after the fair, the state Health Department said, lowering the risk to humans.

“As the birds were not showing signs of infection at the time of the fair, the likelihood of spreading H5N1 to humans is low. However, out of an abundance of caution, DOH recommends that individuals who attended the fair and touched a duck or goose monitor for influenza-like illness (ILI) and conjunctivitis,” the state said in a release. 

A quarantine order was issued for the property where the birds lived and all will be required to be “depopulated and the premises cleaned and disinfected,” the state Agriculture Department said. An order was also issued to prevent any animals from being moved in or out of the site.

At least 10 birds, which included ducks, a goose and a zebra dove, had been reported dead at the property on Nov. 12. Samples from the dead birds were sent to be tested for the virus.

Closely watching for human cases

Confirmation of the infected flock in Hawaii follows a detection of the virus in the area from wastewater samples collected by the state earlier this month.

Health officials around the country have been closely watching for signs of H5N1 spreading in their communities amid mounting cases in humans across North America.

At least 53 cases have been confirmed across seven states so far this year, the federal Centers for Disease Control and Prevention (CDC) says. Most are linked to the B3.13 version of the virus that has been infecting workers at dairy farms and nearby poultry farms in recent months. None of them are known to have been severely ill.

Health officials in Canada announced this month that they had detected a case of H5N1 bird flu in a critically ill hospitalized teenager. That patient had been infected by the D1.1 genotype of H5N1, which is related to another ongoing poultry outbreak in British Columbia, the Canadian province where they lived.

Experts say the virus that infected the teenager does appear to have some worrying mutations, which might explain why the case was more severe.

“The preliminary sequence from the H5N1 human case in British Columbia has been posted and it is not good news,” Scott Hensley, a professor of microbiology at the University of Pennsylvania, posted on Nov. 16.

Genetic sequencing data from human cases so far in the U.S. have not found any signs of the virus mutating to spread more efficiently between humans or to be significantly more dangerous, the CDC says.

But the agency also recently found evidence that several cases had been asymptomatic and gone undetected during the outbreak so far, prompting stepped up testing recommendations.