Current antivirals may be less effective against severe infection caused by bird flu virus in cows' milk: Study

Existing antivirals may be less effective against this H5N1 bird flu strain, and prevention measures, such as avoiding raw milk consumption and reducing exposure in dairy workers, may be the most effective way to protect against the virus.

Scientists found that frequently used flu antivirals do not work well against the H5N1 avian influenza virus in cows' milk.

 

Existing antivirals may be less effective against this H5N1 bird flu strain, and prevention measures, such as avoiding raw milk consumption and reducing exposure in dairy workers, maybe the most effective way to protect against the virus.

 

As the H5N1 avian influenza outbreak continues in the United States, scientists are working to better understand the virus's threat to human health.

 

The virus has been found in dairy cows' milk and has infected farm workers, prompting scientists at St. Jude Children's Research Hospital to study potential treatments.

 

Results showed that in a preclinical model, two FDA-approved flu antivirals generally did not successfully treat severe H5N1 infections. Additionally, the researchers found that the route of infection, whether through the eye, the nose or the mouth, significantly impacts a treatment's effectiveness.

 

The findings were published today in Nature Microbiology.

"Our evidence suggests that it is likely going to be hard to treat people severely infected with this bovine H5N1 bird flu strain," said corresponding author Richard Webby, PhD, St. Jude Department of Host-Microbe Interactions.

 

"Instead, reducing infection risk by not drinking raw milk and reducing dairy farm workers' exposures, for example, may be the most effective interventions."

 

Though H5N1 infections in people are rare, there are more than 60 people who have become infected from dairy exposures to date in the current outbreak.

Some were infected through exposure to contaminated raw cows' milk, such as dairy workers who were infected through splashes or aerosolized particles reaching their noses or eyes.

 

Given the risks to human health, the scientists used a mouse model to test how each antiviral drug worked against the virus when it was obtained through three different exposure routes.

 

"In general, baloxavir [Xofluza] caused a greater reduction in viral levels than oseltamivir [Tamiflu], but neither was always effective," said first author Jeremy Jones, PhD, St. Jude Department of Host-Microbe Interactions.

 

The researchers studied exposure routes that included the eye, mouth and nose, which are the most common ways to become infected with the virus. The oral route, which mimics drinking raw infected cow's milk, caused the worst infections that were hardest to treat.

 

In contrast, findings showed that baloxavir controlled infections through the eye fairly well. These results are particularly relevant as the ocular route appears to be the common infection pathway for people who work directly with dairy cows.

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