What To Know about The H5N1 Bird Flu Virus

Infectious disease experts are closely monitoring cases of H5N1 or avian flu in animals as well as humans. While Centers for Disease Control (CDC) has identified at least 66 human cases, the risk of infection to people remains low.

“When bird flu does infect a human, the mortality rate is about 50%” said Yale New Haven Hospital Infectious Disease specialist Scott Roberts, MD, assistant professor in infectious diseases at Yale School of Medicine. “For that reason, there’s a lot of concern about how this will adapt. Is it going to evolve and lead to a human pandemic down the road?”

A new mutation was recently identified in a patient in Louisiana. The mutation was not identified in animal samples taken from that patient’s farm, suggesting the virus mutated while in the patient. Dr. Roberts says this indicates the virus is mutating to better be able to infect humans.

How does bird flu spread?

Human strains of the flu are typically spread through respiratory transmission. However, Dr. Roberts says it’s likely humans and other animal species are getting infected with bird flu in other ways. For example, an animal may eat an infected bird, or a human may encounter a contaminated bird’s secretions, or touch their eyes after touching a sick bird.

What are bird flu symptoms?

Symptoms of bird flu are similar to the regular flu including:

• Fever
• Cough
• Sore throat
• Runny nose
• Body aches

One person who had a confirmed case also presented with an eye infection.

Currently there have been rarely identified cases of human-to-human transmission. It’s more likely to appear in people who have close contact with sick animals, like poultry farmers. Therefore, testing is not currently recommended for the average person. However, anyone with symptoms who works on a farm should tell their doctor.

Tamiflu, which is also used to treat H1N1 and H3N2 appears to be effective at blocking the viral replication in H5N1.

Is there bird flu in milk?

Since bird flu has been showing up in cows and chickens, should we worry about the milk and eggs we eat? The U.S. Food and Drug Administration (FDA) says remnants of bird flu have been found in samples of pasteurized milk but deemed the milk supply safe because it was not a live, viable virus.

“There's little risk of transmission in eggs and milk because you need to have direct contact with the infected animal itself. But more than that, the pasteurization process would kill any viable virus in there,” said Dr. Roberts.

In addition, farmers are incentivized to swiftly identify and kill sick flocks to prevent these products from ever entering the supply chain. To be on the safe side, Dr. Roberts recommends avoiding raw products, and instead sticking to pasteurized milk and eggs.

Bird flu in cats and other animals

While bird flu has mostly been identified in wild and farm animals, cases have also been found in some domesticated animals including cats. These cases have been linked to pets eating raw foods, so it is recommended pet owners use the same precautions recommended for humans: Avoid raw products. Anyone concerned about possible infection should speak with their veterinarian.

How to avoid getting bird flu

Of course, people should also avoid areas of outbreak. Because while the threat of bird flu to humans is currently low, Dr. Roberts says current trends should serve as a warning because the virus will continue to mutate over time.

“People are certainly more aware of the threat of pandemics now than they were five years ago,” said Dr. Roberts. “In contrast to COVID, we know this is circulating and we know this is a growing problem. So hopefully that gives us enough planning time where we can stop any future potential pandemics 10 years down the road.”

Bird flu vaccines already exist, but Dr. Roberts says they are old and likely have diminished efficacy against these new outbreak strains. An updated vaccine is underway, but the success of a bird flu vaccination campaign would depend on the resources provided for that effort.