Bird Flu Hits Dairy Cows in California – Number 1 Milk Producing State in US

Cows in California have tested positive for highly pathogenic avian influenza (HPAI) and are now in quarantine, according to the state's Department of Food and Agriculture (CDFA).

California hosts a fifth of the nation's dairy cows, and it is the number one producer of milk, butter, and ice cream, and the number two producer of cheese and yogurt in the US.

A CDFA statement assures the public that the state's supply of pasteurized milk and dairy products remains safe for consumption, but an outbreak of bird flu at three different dairy farms is an event officials are not taking lightly.

"We have been preparing for this possibility since earlier this year when HPAI detections were confirmed at dairy farms in other states," says CDFA Secretary Karen Ross.

"Our extensive experience with HPAI in poultry has given us ample preparation and expertise to address this incident, with workers' health and public health as our top priorities. This is a tough time for our dairy farmers given the economic challenges they're facing in a dynamic market, so I want to assure them that we are approaching this incident with the utmost urgency."

The current infections of HPAI among cattle in the US started in March, when a 'mysterious' illness broke out among dairy cows in Texas, causing thick and discolored milk.

These cows were the first in the world to officially test positive for the bird flu virus.

Thankfully, the infection seems to be non-lethal, but it does cause a temporary drop in milk production for a week or more. Officials still don't know how the virus is transmitted from cow to cow, but it's possibly spreading through contaminated milking machines.

Only if dairy milk is raw or unpasteurized does it pose a threat to humans.

Since March, the US Department of Agriculture (USDA) reports that 197 cattle in total have tested positive for bird flu in no less than 14 states, including Kansas, Michigan, Idaho, Ohio, Colorado, South Dakota, Minnesota, Oklahoma, Iowa, Wyoming, and New Mexico.

In the last 30 days alone, there have been 17 confirmed cases of bird flu among dairy cows in four states.

On 30 August 2024, three livestock herds in California joined the list. Colorado, meanwhile, is dealing with an outbreak among 12 livestock herds.

At the moment, no domestic poultry flocks are affected by the avian flu in California, which suggests the cows were infected not via birds but from their own kind.

No human cases have been detected in the state, but public health officials urge dairy workers to remain vigilant and to wear protective equipment while handling raw milk.