Highly-pathogenic avian influenza has spread to 93 dairy herds in California, but dairy industry officials are uncertain what it means for milk supplies.
Usually the disease in cattle is mild, but is deadly to poultry. It is turning out to be more serious among cattle than previously thought.
California has about 1,100 dairy herds and 1.7 million cows which account for about 20 per cent of the U.S. milk supply.
State and federal health authorities insist that H5N1 poses little threat to humans and that it is safe to drink milk that has been pasteurized, because the process kills the virus.
However, dairy farmers and veterinarians are reporting far greater rates of mortality among infected herds than anticipated and steep drops in the rate of milk production among recovered cows.
At the same time, some epidemiologists fear that as the virus spreads among California farms, it greatly increases the odds that it can mix with a human virus and create a health threat for people.
“I was shocked the first time I encountered it in one of my herds,” said Maxwell Beal, a Central Valley-based veterinarian who has been treating infected herds in California since late August.
“It was just like, wow. Production-wise, this is a lot more serious than than we had hoped. And health-wise, it’s a lot more serious than we had been led to believe.”
