Bird Flu Spreads To SoCal Dairy Farms: What To Know

SAN BERNARDINO, CA — The H5N1 bird flu has been detected at four dairy farms in Southern California, public health officials announced on This week.

The affected farms are located in San Bernardino County, which was home to some 809 farms in 2022, according to the latest census report from the U.S. Department of Agriculture. The county also hosts at least 63 registered egg handlers, according to data from the California Department of Food and Agriculture.

For infected laying hens, avian influenza in poultry is controlled through the rapid euthanasia of any flock that tests positive or is presumed positive, according to Richard Blatchford, associate specialist of Cooperative Extension at the UC Davis College of Agricultural and Environmental Sciences.

But at dairy farms like the ones recently affected in San Bernardino County, the response can look a little different.

Since cattle are much more expensive than hens tend to be and they don't become as sickened as birds, cattle are generally treated before they are released back into their herd. The next step in terms of biosecurity could be an avian flu vaccine for livestock, Blatchford speculated.

Since the outbreak began in 2022, more than 166 million laying hens have been killed in what has been deemed the worst bird flu outbreak in recent memory.

The rapid spread of the disease continues to bedevil consumers as the cost of eggs hit a record high in January.

U.S. egg prices hit an average of $4.95 per dozen in January, surpassing a previous record set in January 2023, according to federal data. In some parts of the country, they’re much higher. A Safeway supermarket in San Francisco was selling a dozen eggs for $10.99 this week.

And while experts assure that human infection remains "relatively low", officials are urging the public to take caution — particularly those who are in frequent, close contact with laying hens, dairy cows or wildlife.

Because it is a respiratory virus that is spread by breathing air containing viral particles of infected animals, experts say people who work with infected dairy cows or raw milk should use protective gear to reduce the risk of contracting bird flu.

At this time, experts say bird flu poses very little risk and is very rare for humans, but it did kill one person in the U.S., officials confirmed on Jan. 6. Since the outbreak began in the spring of 2022, 38 of the nation's 67 human cases, have occurred in California, according to the Centers for Disease Control and Prevention.

“The detection of this virus in animals across multiple farms serves as a reminder to practice caution when handling animals or animal products,” said Sharon Wang, San Bernardino County's health officer. “It’s crucial to avoid raw milk consumption and follow proper food safety practices to reduce any potential risk of exposure.”

The news of the bird flu detection in San Bernardino County comes shortly after the first-ever discovery of the virus in four black rats in neighboring Riverside County in mid-February — the only place in the nation where such rodents have tested positive.

As bird flu exacerbates a chicken-and-egg problem at unprecedented levels, reports of infections in humans, their pets, and other mammals have continued to surface.

Following the detection of avian flu in rats, rodent control is becoming an important part of biosecurity efforts, Lyndsay Cole, a spokesperson for the United States Department of Agriculture, previously told Patch.

This is because the virus can spread through saliva, blood, urine and feces.

Cole said there hasn't been any evidence of rats or other rodents spreading the virus directly to other species. However, transmission isn't impossible as rodents transport wildlife feces and secretions onto equipment and facilities, she said.

The outbreak took another unexpected turn recently when it began killing domestic cats.

Blatchford says we're in "unknown territory."

But the largest concern about bird flu is how it will evolve as it spreads.

"It's evolution alongside seasonal flu and other strains, could, in the future, produce new versions of the virus that spread more easily among humans," said Rais Vohra, a professor at UC San Francisco and interim health officer for the Fresno Department of Public Health.

Symptoms of H5N1 in humans:

• Eye redness or discharge
• Cough or sore throat
• Runny or stuffy nose
• Diarrhea or vomiting
• Muscle or body aches
• Headaches
• Fatigue
• Difficulty breathing
• Fever

Blatchford, an expert on the welfare of small-to-large-scale poultry production, echoed that sentiment.

"Every time it infects an organism, it mutates," he said. "And so the worry is generally that the more it infects mammalian species, the more likely it is to become a virus that is much more like the flu viruses that we already contract and can spread from person to person."

READ MORE ABOUT BIRD FLU:

• Bird Flu Symptoms: New Strain Discovered In CA As Outbreaks Spread
• When Will Bird Flu End? UC Riverside Experts Weigh In
• Bird Flu Detected In 4 RivCo Rats: What To Know