The H5N1 strain of Avian Influenza-commonly known as bird flu-has been making significant strides into domestic territories, sparking concern among scientists and public health officials. Over the past two years, the virus has been circulating among wild migratory birds, with substantial spillover into poultry farms. However, the recent discovery of the virus in dairy cows and the subsequent infection of a dairy farm employee—the second person in America so far—has raised eyebrows in the scientific community. As of now, the virus has spread to 16 herds across six states, according to the United States Department of Agriculture (USDA), raising fear regarding potential further transmission to humans.
Johns Hopkins Public Health experts, however, suggest that though the virus is now seen circulating among dairy cows, the risk of human exposure still remains quite low.
Avian Flu Q&A with Professionals
Stephanie Desmon from Public Health on Call held an enlightening Q&A on April 8, speaking with Meghan Davis, an Associate Professor in the Department of Environmental Health and Engineering, and Andrew Pekosz, a Professor in the Department of Molecular Microbiology and Immunology. They discussed the bird flu’s jump between species, its pandemic potential, and the impact of the virus appearing in the dairy industry.
What’s Going on With the Avian Flu?
According to Pekosz, the virus’s increased activity in the last couple of years is of concern. It’s been mutating over time and has seen an alarming spike in incidences of infecting wild birds. This in turn has led to increased spillover infections into poultry farms and other mammals, including skunks, bears, and foxes who presumably contracted the virus by feeding on dead infected birds. Alarmingly, the virus has also recently spilled over into dairy cows.
Was the H5N1 Outbreak Unexpected?
Davis expressed surprise that the outbreak has reached dairy cows, as when it comes to animal models for influenza, mustelids such as ferrets or mink are generally considered. The surprising part about seeing H5N1 in dairy is that researchers have not typically focused on biosecurity and biocontainment for viruses like Avian Influenza, which is typically transmitted from bird reservoirs. As a potentially consequential symptom of disease, some infected cows stop eating or milking well, though there’s no report of high mortality yet.
Is the Consumed Milk Safe?
There’s no substantial evidence suggesting concern for the average person consuming commercial milk. If the milk is pasteurized and procured from a commercial dairy processor, the risk is extremely low. Davis advises strongly against the consumption of raw milk products due to the associated risks.
What Can We Learn From Infected Cows?
The infection pattern in cows tells us two important things, as per Pekosz. First, the virus, upon entering a new host, has traveled beyond the respiratory tract and made it all the way into the milk. This suggests something unique about the H5N1 virus in contrast to common human strains. Second, if the virus transmits from cow to cow, it indicates the virus is adapting and becoming better fit to spread in cows. This information is critical in understanding the virus’s potential to infect humans and how the sequence of the virus changes.
What About the Transmission Among Cows?
Davis brings attention to the way cows are frequently moved and swapped in the dairy industry, and the potential need to educate farmers about this if it poses a risk of introducing bird flu. And Pekosz suggests that contaminated milking equipment could contribute to the virus spread, as the amount of virus in the milk is much greater than in the cow’s nose. Hence, instituting equipment disinfection protocols could slow or stop the virus spread.
Is Avian Flu a Major Threat at This Time?
Pekosz admits that H5N1 does pose a pandemic potential. As humans have very little inherent immunity against H5 viruses, there could be massive increases in the number of cases if the virus enters and starts to spread among humans.
For the average person, Davis suggests simply being aware of the situation and avoiding things like raw milk products. Moreover, since the possibility of disease in cats has been observed, it’s a good idea to limit your cats’ contact with wild birds.
