Bird Flu Detected In 4 RivCo Rats: What To Know

RIVERSIDE COUNTY, CA — For the first time, avian flu has been detected in rats — a discovery made in Riverside County earlier this month.

The four black rats that tested positive were reportedly living in an area where two poultry farms had been infected, the Los Angeles Times reported.

As bird flu continues to hamper the supply of eggs across the country, more reports of infections in humans, their pets and other mammals have surfaced.

Since the virus — H5N1 — can spread through saliva, blood, urine and feces, rodent control is becoming an important part of biosecurity efforts, Lyndsay Cole, a spokesperson for the United States Department of Agriculture, told Patch.

"The finding of HPAI in rats is not unexpected, as we know rodents and many other species of mammals are susceptible to the virus," Cole said on Friday.

Currently, Cole says there is no 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.

Riverside County's Department of Public Health was unable to comment on the detection and could not confirm which agency tested the rats.

Riverside County is currently the only place in the nation where black rats have tested positive for the virus. The avian flu detection was confirmed on Feb. 14, according to USDA.

And while this is the first known instance of transmission to a black rat, it isn't the latest mammal to test positive in California.

On Feb. 20, another domestic cat in Imperial County was infected, according to data from USDA. Since 2022, nearly 100 domestic cats have tested positive for bird flu.

Bird flu has continued to bedevil egg production facilities, poultry farms and consumers alike as egg prices soar. California is being hit particularly hard this time, compared with past outbreaks.

What's more, the U.S. Agriculture Department predicts record egg prices could skyrocket more than 40 percent this year.

Egg prices have climbed alongside the euthanasia of more than 166 million birds to limit the spread of the infection where it's found.

"Infected chickens show signs of severe illness or death very quickly, and the current standard practice is to euthanize the entire flock if the virus is detected on a property," according to Amy Murillo, assistant professor of veterinary entomology at University of California, Riverside.

READ MORE: When Will Bird Flu End? UC Riverside Experts Weigh In

Since avian flu quickly kills birds within 24 to 48 hours, euthanasia is considered the most humane and effective way to keep the spread at bay. But with no signs of the outbreak slowing, experts remain concerned about long-term effects on poultry supply and food prices, poultry production expert, Richard Blatchford, previously told Patch.

As the virus continues to spread to new mammals, Blatchford says we're in "unknown territory."

Blatchford is an Associate Specialist of Cooperative Extension at the UC Davis College of Agricultural and Environmental Sciences.

The sheer speed of spread has also been concerning. Outbreaks have spread from remote farming communities to the more populous part of the state, with outbreaks in Southern California's Inland Empire.

"We’ve never seen a global spread of avian influenza virus like this,” Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota told Time. “We’ve seen an explosion in the number of outbreaks in poultry and duck operations over the course of recent weeks. This reflects the fact that there is so much H5N1 in migrating waterfowl."

READ MORE: Bird Flu Symptoms: New Strain Discovered In CA As Outbreaks Spread