Bird flu continues to spread across the United States and behave in uncanny ways.
Last week, a Louisiana resident became the first human in the country to die from the H5N1 influenza virus, after being hospitalized with severe illness. The patient, who was older than 65 and had underlying health conditions, contracted the infectious disease from exposure to wild birds and a backyard flock of chickens, the Louisiana Department of Health reports.
Experts monitoring and investigating the virus say the news is not a reason to panic, and the risk remains low to the public. But the rapid rate at which H5N1 is infecting not only wild birds and poultry but also cattle and other mammals, including humans, raises concerns for infectious disease experts, who say that additional tracking and preventive measures are necessary: If the virus mutates in a way that allows it to pass from one human to another, experts fear it could become an epidemic or pandemic.
To prevent the spread of avian flu:
- Avoid raw milk products and raw or undercooked meat products, including eggs; consume pasteurized milk and pasteurized milk products only
- Do not touch or handle dead or dying birds, animals, and mammals
- Protect your pets: Keep cats indoors, keep dogs away from areas with migratory birds, and avoid feeding raw milk and raw meat pet food diets
- Contain backyard chickens and change your clothes and wash your hands after visiting the coop
“At this point, we’ve seen no evidence of human-to-human transmission,” says Johns Hopkins molecular epidemiologist and environmental microbiologist Meghan Davis. “Signs indicate that it could happen, but no one knows for certain whether it will or not.”
Davis, who spent more than a decade working as a veterinarian, is an associate professor of environmental health and engineering at Johns Hopkins’ Bloomberg School of Public Health, with joint appointments in the School of Medicine. Recently, she had a discussion with the Hub regarding the changing bird flu situation and provided advice for the public on how to stay safe.
H5N1 has been a concern for some time, but what makes it particularly worrisome now is its ability to persist and spread to dairy cows and other mammals. This unusual behavior, including infecting marine mammals in South America, is a cause for concern as the virus continues to evolve and adapt.
The symptoms of H5N1 vary depending on the source of infection, with wild birds and backyard flocks causing more severe respiratory symptoms, while infections from dairy cows may present as milder flu-like symptoms with conjunctivitis. The differing severity and symptoms are due to the different genotypes of the virus associated with each source of infection.
The ability of the virus to adapt and change, as well as the varying levels of illness it can cause, highlight the importance of taking precautions to prevent exposure. Studies have shown that some individuals infected with H5N1 may experience no symptoms, potentially contributing to the virus’s ability to mutate and spread. Therefore, we are essentially conducting an experiment where the more times we flip the coin, the higher the likelihood of achieving five heads in a row, which in this case, translates to human-to-human transmission or a more consistently severe illness.
Do we see signs indicating human-to-human transmission? Yes, sustained animal-to-animal transmission has been observed, raising concerns about the adaptability of the virus. There is a possibility of the virus jumping from cows to birds and back to cows, although not confirmed. The more the virus mutates, the higher the chances of human-to-human transmission, as influenza viruses are known for their mutation capabilities.
What would trigger H5N1 to become a pandemic? A potential scenario involves a co-infection of H5N1 with another strain of influenza, like the seasonal flu, in a person or animal. This could lead to the virus reassorting and gaining characteristics that make it more transmissible among people, crossing the threshold towards a pandemic.
How is the virus being monitored and controlled? State governments, with federal support, are tracking and reporting cases. However, the numbers reported may not reflect the full extent of the outbreak. Measures like increased milk testing and better surveillance are being implemented to identify unreported cases in both humans and animals.
How can we halt the spread of H5N1? Containing the virus is challenging, especially in states like California with close-knit dairy farms and migratory bird pathways. Improving biosecurity measures on farms and addressing factors like migratory bird presence can help prevent further spread of the virus.
