Highly pathogenic avian influenza (HPAI) can spread among dairy cows via virus from birds, pigs and humans and even into cows’ udders, report researchers at Iowa State University’s College of Veterinary Medicine.
Examining tissues of infected dairy cattle revealed that both the cows’ mammary glands and respiratory tissues had receptors for flu strains that originated from birds, as well as humans and pigs, the university said in a news release.
The presence of the receptors in the udders of dairy cows is new, and indicates how the HPAI virus has spread to samples of raw (unpasteurized) milk.
Of broader concern is the presence of receptors from both avian, and human and swine, origin, as a single cell infected by avian and mammalian viruses could lead to potentially dangerous mutations, they said.
Cows’ udders are apparently susceptible to HPAI transmission when there is a supply of a sugar called sialic acid in the mammary glands.
The connection could shed light on how the virus attaches to hosts and help develop measures to slow the spread.
At least the research indicates that the glands are part of the direct vector of transmission of the virus, as opposed to being passively infected as the virus is transmitted along other pathways.
The research is detailed in an article in the July 2024 issue of the Centers for Disease Control and Prevention’s peer-reviewed journal, Emerging Infectious Diseases.