Forbes Scientists have proven how cows have spread H5N1 bird flu across the country and infected other cows, wild birds and even mammals like cats and raccoons, according to research published in Nature Wednesday, findings that suggest it may be capable of spreading effectively between people in the future as outbreaks on poultry and dairy farms spark concerns the virus could trigger a pandemic in humans. Using genomic data, computer modeling and data about the virus’ spread, researchers from Cornell University have shown how infected cows from Texas spread H5N1 avian influenza to a farm with healthy cows in Ohio, as well as to cats, a racoon and wild birds in the area.
It is one of the first times scientists have seen “evidence of efficient and sustained mammalian-to-mammalian transmission” of the H5N1 bird flu strain, said Diego Diel, an associate professor of virology at Cornell and one of the study’s authors.
While it primarily infects birds, the so-called highly pathogenic avian influenza strain is capable of infecting mammals—including humans—and Diel said repeated spillovers into mammals from birds or transmission between mammals raises the risk of the virus mutating in a way that “could lead adaptation to mammals, spillover into humans and potential efficient transmission in humans in the future.”
This H5N1 strain is particularly capable of targeting and infecting cells for the mammary gland, a specialized gland that produces milk and is unique to humans and other mammals, the researchers found, and milk from infected animals contained high quantities of the virus.
Genetic data showed the infected cows transmitted the virus to cats and a racoon found dead at affected farms, likely through drinking raw milk from infected cows, as well as wild birds, which the researchers suspect were infected from environmental contamination or aerosols kicked up during milking or cleaning.