“Bird flu” continues to pose challenges for public health officials. They are increasingly concerned about the potential for person-to-person transmission of H5N1 influenza. This strain of influenza has been circulating in wild birds for decades. The first human cases were reported in 1997, when 18 people were infected in Hong Kong. Six of them died, which is a very high rate of mortality. The virus was not spreading between patients, however. All of the people who became ill at that time had contact with infected poultry such as chickens, ducks or geese. In subsequent years, various forms of this influenza virus spread around the globe. Although some humans became ill, for the most part the virus was confined to birds.
Can H5N1 Influenza Spread Among Humans?
That changed last year. Throughout 2024, public health officials worried about the sparse evidence that dairy cattle were contracting and transmitting the virus. Although several human cases were reported, most were agricultural workers with close contact with cattle. It seems that may not continue, though.
In Missouri, an individual no known contact with chickens or cows became ill with H5N1 influenza in early September. Since then, the CDC has reported that 3 additional people in contact with the patient also developed symptoms. One was a member of the same household. The two other cases occurred in healthcare workers who looked after the original patient.
This cluster raises the fear that the H5N1 virus has mutated so that it can spread from one person to another. Public health officials have been downplaying the risk, but the acting director of epidemic and pandemic preparedness and prevention at the World Health Organization is calling for better surveillance and testing in the US. She is also calling for improved collaboration between animal health experts and human health sectors.
At last count there have been 14 confirmed human cases of H5N1 influenza in the US. If this virus begins to infect people the way it has attacked poultry and cattle, we could be in for another pandemic. That is why we think it is imperative to act swiftly to track and treat it. Perhaps with intervention and attention to OneHealth priorities, we could prevent pandemic problems.
