A recent outbreak of avian influenza in Nevada has raised concerns about the potential threat to humans due to a genetic mutation that may allow the virus to copy itself more easily in mammals, including people.
According to a technical brief from the US Department of Agriculture’s Animal and Plant Health Inspection Service, a dairy farm worker in Nevada recently tested positive for H5N1, the first human infection identified in the state. The worker exhibited symptoms such as red, inflamed eyes or conjunctivitis.
Scientists are closely monitoring the situation due to the genetic change found in the affected cattle, which is associated with D1.1, a subtype of the H5N1 virus linked to two severe human infections in North America.
Researchers believe that the cows encountered infected birds or their droppings before becoming infected, and that wild birds may have brought the mutated strain onto farms. This new variant has a mutation that enhances its replication efficiency into mammalian cells.
“This mutation provides the virus with the ability for enhanced replication, which poses a threat to humans that are exposed to these cows,” said Dr. Seema Lakdawala, a microbiologist and immunologist at Emory University.
The situation highlights concerns about why some bird flu viruses, like B3.13, have been mild in humans despite being high-pathogenic in birds. Scientists theorize that the changed N segment of the D1.1 virus may help evade immunity from seasonal flu strains, increasing the potential for more severe infections.
Experiments are underway to investigate whether the N segment of the mutated virus allows the H protein to change and infect humans more easily. The Centers for Disease Control and Prevention (CDC) is investigating further clues to understand why D1.1 was associated with two severe human cases.
Source: https://edition.cnn.com/2025/02/08/health/bird-flu-variant-nevada-human-case/index.html