A genetic mutation of the H5N1 bird flu virus—a mutation associated with increased infectiousness and disease severity—has been found in two cats, in what scientists say is another indication of the risks posed by the virus.

Mutated H5N1 Bird Flu Found in Cats: Scientists have identified a genetic mutation in two infected cats that is linked to increased infectiousness and disease severity. Mutation Similar to One Found in Cows: The mutation, PB2 E627K, is similar to one found in San Bernardino dairy cows, though the cats were infected with a different strain.

Scientists are sounding alarms about a genetic mutation that was recently identified in four dairy cow herds, nearly one year after H5N1 bird flu was first reported in Texas dairy cattle.