dairy

Dairy industry experts say the virus entered California after local cows were shipped to another state and then returned to California.

Centers for Disease Control and Prevention shows the virus is more widespread in dairy workers than had previously been assumed.

An examination of antibodies in 115 dairy workers from Michigan and Colorado showed that eight people were positive for the disease, or 7% of the study population — indicating that either workers were not reporting illness, or they were asymptomatic.

Nuzzo also pointed to a recent study published in Nature, led by Yoshihiro Kawaoka, an H5N1 expert at the University of Wisconsin, in Madison, that showed the virus that infected the first reported dairy worker in Texas had acquired mutations that made it more severe in animals as well as allowing it to move more efficiently between them — via airborne respiration.

Although California dairy farmers anticipated a bird flu mortality rate of less than 2%, some say between 10% and 15% of infected cattle are dying.