As California's Central Valley makes headlines for the growing number of people testing positive for the bird flu from exposure to dairy cows, Rais Vohra , MD, professor at UC San Francisco, Fresno and interim health officer for the Fresno Department of Public Health (DPH), is in the eye of the storm. An emergency medicine physician, Vohra serves as the medical bridge between county health and farmers, and guides prevention protocols for Fresno and neighboring Tulare and Kern counties, where dairy and poultry farms have been directly impacted by the virus.
Vohra explains what we know about bird flu and the precautions we can take to prevent it from becoming a public health emergency.
What is bird flu?
Bird flu is a common name for the H5N1 virus, a strain of influenza that has been affecting wild birds and poultry for decades. This strain was originally seen in wild birds and poultry farms but made the jump from birds to mammals in a Texas dairy cattle ranch in March 2024, and is now knocking on the door of humans.
How many cases of the bird flu have we seen in the U.S. in 2024?
From April to mid-October, there have been 20 confirmed human cases of bird flu in the U.S. Six of those cases were in California's Central Valley.
How does it spread?
We know that this is a respiratory virus and is not bloodborne. It is spread by breathing air containing floating viral particles, similar to the common cold.
Has there been any recorded instance of human-to-human transmission in the U.S.?
No.
Is it highly contagious?
So far, it is mainly contagious among poultry and dairy cows. Farmers who tested positive in California have all been in close contact with dairy cows, so all dairy farms in the Central Valley are on alert. None of the six California patients were in contact with each other, nor did they transmit the virus to others in their household.
Is there a vaccine to protect people from the bird flu?
Yes and no. Vaccines for the bird flu are in development and are being actively researched, but nothing is available to the public at this time.
Will the seasonal flu vaccine protect the public from the bird flu?
No, the seasonal flu vaccine will not protect patients from catching the bird flu. However, I strongly encourage everyone to get this year's flu vaccine, especially those who work closely with dairy cattle or poultry farms. There is a concern among infectious disease experts that if a person with the common flu virus also becomes infected with the bird flu, the two viruses in the same body could mutate causing variants that will more easily spread through human contact.
