New Yorkers, beware: If you encounter a sick, dead, or strangely behaving bird or animal, keep yourself and your pets a safe distance away. The avian influenza virus, H5N1, is present in at least a small fraction of New York City's birds, according to a new study.
The finding is not entirely surprising, given that H5N1 has been shown to affect migratory birds, a wide range of wildlife, poultry and, as of last month, dairy cows. However, its discovery in the city is an unpleasant reminder that urban spaces are not exempt.
People generally associate zoonotic diseases with rural environments, farms or wilderness, said Florian Krammer, an influenza expert at the Icahn School of Medicine at Mount Sinai in New York who led the study, published online last week.
But New York City has many green spaces and bodies of water used by migratory and native birds, he said: “There's a lot of interface between wild animals and humans in cities.”
“There is no reason to panic, but it is good to be aware,” he added.
Last week, the Centers for Disease Control and Prevention warned health workers to watch for signs of avian flu infection. So far, only two Americans have been reported infected with H5N1, one in 2022 and the other earlier this month.
The virus has caused large epidemics among mink and foxes and wiped out thousands of marine mammals, especially in South America. Scientists have tracked the virus along migratory routes and stopovers, among wild birds in rural areas and on commercial poultry farms, and, more recently, among cattle on dairy farms.
But now the virus “is everywhere,” said Seema Lakdawala, a virologist at Emory University. “I would be surprised if in any urban environment I went to, I didn't find a small percentage of H5.”
“This is an important lesson for all big cities,” he added.
Migratory birds and other species live in urban green spaces and wetlands, where they may encounter scavengers, such as squirrels, pets, and even people. Cats and dogs are susceptible to the avian influenza virus and can contract the virus from infected birds, their feces or contaminated water.
“People don't think there's a lot of wildlife in New York City, but we're actually quite wealthy,” said Rita McMahon, director and co-founder of the nonprofit Wild Bird Fund, a wildlife rehabilitation center in New York City.
The new study is a product of the New York City Virus Hunters initiative, a collaboration between the rehabilitation center, Mount Sinai scientists, community members and a scientific outreach organization. Includes high school students who belong to minority groups underrepresented in science.
From January 2022 to November 2023, the researchers collected samples of bird species ranging from wild ducks and geese to shorebirds and birds of prey. Some birds were already dead; others showed neurological symptoms and were euthanized.
Among about 1,900 samples taken from the animals, they found versions of H5N1 in six, four species: Canada geese in the Bronx and Queens; a red-tailed hawk near a major highway in Queens; a Canada goose and a peregrine falcon in Brooklyn; and a chicken in Upper Manhattan.
The researchers were not surprised to find the virus in Canadian geese and birds of prey, but “it was somewhat unexpected to receive samples from a chicken found in Marcus Garvey Park,” they wrote.
Since the end of the study the team has found two more infected birds. “My expectation is that as we continue to look, we will find more,” Dr. Krammer said. The low number of infected birds found so far could be the result of the test used by the researchers, which does not detect small amounts of the virus, he said.
Dr. Lakdawala praised the scientific aspect of the project as a way to collect more samples than would be possible with formal surveillance efforts alone, while also educating the public about safe sample handling.
“The USDA can't do everything, the CDC can't do everything,” he said, referring to the federal agencies that normally carry out such surveillance. “We really need broader networks so we can get a better picture of what's happening and what the viruses are.”
At the same time, he said, residents should be responsible and not touch a dead bird. The New York City Health Department advises residents to report sick, dead or strangely behaving birds and animals by calling 311.
Every year, about 9,000 people bring injured wildlife – from songbirds and pigeons to squirrels and possums – to the Wild Bird Fund's rehabilitation center. Some people are in tears. Others “go as far as kissing a sick goose, thinking that would help the situation,” Ms. McMahon said.
But now, New Yorkers should be even more cautious when they see an injured or sick bird or animal, he said.
“That doesn't mean they can't save him and bring him to us,” Ms. McMahon said. But people should wear gloves, wrap the animal and take other precautions.
And “no kissing,” he said. “Direct physical affection is not an advantage to the animal.”