United States: The origins of the bird flu in dairy cattle remain unknown. However, recent cases have been reported in both North Carolina and South Dakota, bringing the total number of affected states to eight.
Cases of Infection Among Cattle and Humans
Currently, scientists are investigating cases of unexpected infections in dairy workers and cattle to understand the potential animal-to-human transmission, highlighting wildlife as a potential intermediary.
Experts suggest that the risk of infection in mammals depends on the virus’s evolution, particularly its ability to adapt to infect different species.
There is some reassurance, though. Recent findings from the US Department of Agriculture suggest that the virus currently does not exhibit characteristics of respiratory illness in cows, meaning that the animals do not appear to release large amounts of virus from their noses and mouths, as reported by NPR News.
Federal health officials investigating the spread and outbreak suspect “mechanical transmission” within the herd, possibly occurring during the milking process, as the virus is believed to be present in high concentrations in milk.
Thijs Kuiken, a professor of comparative pathology at Erasmus Medical Center, emphasized the unusual nature of this situation, stating, “In other mammalian species with influenza viruses, it’s primarily a respiratory disease, which doesn’t seem to be the case in these cattle.”
Potential Spread to More Mammals
While the virus found in infected animals does not appear to have undergone significant changes to be classified as a new variant, scientists anticipate it could infect more mammals.
Michelle Wille, a senior research fellow at the Center for Pathogen Genomics at the University of Melbourne, warned, “We really need to keep on top of this because I think we are at a bit of a precipice where something interesting or unfortunate could happen,” according to NPR News.
More about the Genetic Strain
Genetic analysis of the virus strain found in Texas among dairy workers revealed a mutation in the PB2 gene, which is known to affect mammals.
Nichola Hill, a disease ecologist at the University of Massachusetts Boston, explained that the prevailing strain of the virus is evolving to replicate better inside mammals. However, this does not necessarily make it more transmissible between humans.