Deadly Bird Flu Strain Doesn’t Spread Easily to Humans

Outbreaks of a deadly strain of bird flu have infected poultry and wild birds across the globe. The H5N1 strain is spreading to more wild bird species than previous outbreaks of bird flu, and the virus has also been found in cattle.

The first human case in the United States was reported in 2022, but the risk remains low. Farm workers and others who have prolonged exposure to poultry are at higher risk. In general, people should avoid contact with wild birds and bird feces, says the Centers for Disease Control and Prevention.

UH infectious disease specialist Keith Armitage, MD, Medical Director of the University Hospitals Roe Green Center for Travel Medicine & Global Health, answers common questions about bird flu.

What is bird flu?

Dr. Armitage: Influenza viruses like those that circulate each year among humans exist in bird populations. The viruses are similar and can exchange genetic information, producing hybrid viruses. There are some flu viruses that exist in bird populations that can cause serious illness in humans. But so far, they have not been highly contagious or spread from human to human.

How does bird flu spread to humans?

Dr. Armitage: The virus is spread through the respiratory tract from droplets or airborne particles. The risk of this happening is low, but if there is significant human contact with poultry, it could happen.

Can it also spread to humans through bird droppings? Can it be transmitted by coming into contact with bird droppings in your yard, for example?

Dr. Armitage: Infection with this virus from bird droppings is very low risk. The real risk is a novel strain that jumps from birds to humans and has the potential to cause serious illness.

Could the bird flu virus mutate to make it more contagious to people?

Dr. Armitage: All viruses have certain properties that make them pathogens. These include the ability to cause infection and evade the immune system, and the ability to spread. There is always the possibility that we could see a novel flu virus that the human population lacks immunity to that is capable of causing serious illness and highly transmissible from human to human. The worldwide influenza pandemic of 1918 was such a scenario.

Is there cause for concern from a public health standpoint?

Dr. Armitage: It is important to continue to invest in public health infrastructure to monitor potential critical public health challenges such as bird flu. But there is no reason for alarm at this point in time.