First Human Dies of Rare H5N5 Bird Flu Strain. Here’s What You Need to Know

The first person has died from a rare strain of bird flu, H5N5. Here's what you need to know

TO Megan Bartels edited by Lewis asked

A person has died from bird flu in Washington state. This is the first human death from bird flu in the US since January – but the infection was of a different strain than the one that was devastating poultry farms And wild animals over the past few years.

Washington State Department of Health announced his death on Fridaynoting that the deceased had been hospitalized since early November. The agency identified them as an elderly man with underlying health conditions who had pet birds in his backyard. It was also confirmed that the virus was of the H5N5 subtype and not a subtype. The H5N1 strain that has caused 70 human infections and one death in the US since 2024, and countless deaths of wild and domestic animals since its arrival in North America in late 2021.

Many influenza viruses are identified by two classes of proteins that appear on their outer shell: hemagglutinin and neuraminidase. Each of these proteins exists in multiple forms, and different combinations of these two types of proteins are called “subtypes” of the virus. The long-circulating H5N1 virus and the H5N5 virus responsible for a recent human death have the same hemagglutinin (H5) protein on their outer envelopes, but different neuraminidase proteins.

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The deaths aren't cause for alarm and don't mean the risk of bird flu is higher than scientists thought, said Richard Webby, a virologist at St. Jude Children's Research Hospital. “We have no reason to suspect that H5N5 has a greater or lesser pandemic risk than H5N1, and similarly we have no reason to suspect that it causes more severe disease overall,” he says. “Most people are exposed to the H5 virus still with the H5N1 virus only because there is so much more of it in the bird population.”

One concern about the new subtype of the virus infecting humans is that the H5N1 avian influenza virus may have exchanged genes with other influenza viruses circulating in animals. Such a mixture— which influenza viruses are particularly susceptible to — can give rise to new viral strains that can cause more severe infections or spread more easily between people.

Scientists have a long history monitoring program for influenza viruses in wild birds which has collected decades of data on where avian influenza viruses are moving and how they are changing. This surveillance program meant Webby and his colleagues knew that H5N5 viruses were circulating among shorebirds and gulls in eastern Canada. Webby says scientists have confirmed that the virus sequenced from the fatal human case is more closely related to viruses from eastern Canada than to the H5N1 viruses; this supports the idea that this is an existing virus that spread westward among birds, rather than a new virus that suddenly appeared in humans.

The Washington State Department of Health said in a statement that health officials are monitoring people who had close contact with the person who died, but no one else has tested positive for bird flu and there is no evidence of transmission of the virus between people.

Keeping backyard poultry is a known risk factor for avian influenza infection. to death from bird flu in the USAwhich occurred in Louisiana in January also involved a man tending a flock of chickens. This person was also over 65 years old and had underlying health conditions.

Public health experts say that people who keep poultry should work to keep their birds separate from wild birds to reduce the chance of contracting the virus to poultry. In addition, people should wear special clothing and shoes that can be worn outdoors when caring for backyard birds, as well as protective gear, such as a mask and goggles, when cleaning the coop. They should wash their hands thoroughly with soap and water after touching chickens, eggs or the coop.

In general, people should stay away from dead wild animals and animals that are acting strangely, as they may be infected with bird flu or another dangerous disease.

Experts also recommend that all children over six months gets a seasonal flu shot if they haven't already done so this fall. The vaccine will not protect against avian influenza, but it will reduce the likelihood of simultaneous infection with seasonal and avian influenza viruses, which can lead to dangerous mixing of viruses.

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