Bird Flu Infection Cases Increase in California

Cows graze in a field at a dairy farm in Petaluma, Calif., on April 26, 2024. Justin Sullivan/Getty Images

New incidents of likely bird flu infections among human beings were identified in California over the past three days, with dairy cattle being the source of the disease, according to the California Department of Public Health (CDPH).

The agency reported six confirmed bird flu cases in the state and five potential cases, according to an Oct. 14 statement. All the reports were from the Central Valley, and the individuals had direct contact with infected dairy cattle.

The five cases now need to be confirmed by the Centers for Disease Control and Prevention (CDC) with samples expected to arrive at the agency this week.

“Given the amount of exposure to infected cows, evidence continues to suggest only animal-to-human spread of the virus in California,” the CDPH stated.

“Additionally, based on CDC’s genomic sequencing of three California bird flu cases, there is no evidence to suggest an increased ability for the virus to infect or spread between people and no known reduced susceptibility to antiviral medications.”

People with confirmed and possible infections all have experienced mild symptoms like eye redness and were treated per guidance from the CDC, the agency noted. None were hospitalized.

The CDPH stated that the risk to the public from bird flu “remains low” but that poultry farm or dairy employees are at higher risk.

The agency advised such individuals to use personal protective gear when working with animals or any material that is infected or potentially infected with the virus.

“To protect California farm workers from bird flu, during the last four months CDPH has distributed more than 400,000 respirators, 1.4 million gloves, 170,000 goggles and face shields, and 168,000 bouffant caps,” the agency stated.

“People exposed to infected animals should monitor for the following symptoms for 10 days after their last exposure: eye redness (conjunctivitis), cough, sore throat, runny or stuffy nose, diarrhea, vomiting, muscle or body aches, headaches, fatigue, trouble breathing, and fever.”

Infections in the US

A total of 20 human avian flu cases have been reported this year in the United States so far since April, according to the CDC. The figure includes 10 incidents linked to exposure to infected birds and nine associated with sick cows.

Ten of the cases were in Colorado, six in California, two in Michigan, and one each in Missouri and Texas.

Since late March, more than 5,000 people have been monitored after they were exposed to infected animals, out of which more than 250 were tested. Over 100 million poultry, more than 10,000 wild birds, and 299 dairy herds have contracted the avian flu virus, according to the CDC.

The federal agency has set aside “more than 100,000 doses of seasonal influenza vaccine to 12 states with dairy herds that have tested positive for H5 bird flu.” The states are California, Colorado, Idaho, Iowa, Kansas, Michigan, Minnesota, New Mexico, North Carolina, Ohio, South Dakota, and Texas.

“CDC also has awarded approximately $2 million in funding to support the operational costs of the various activities jurisdictions are implementing to encourage and facilitate the uptake of seasonal flu vaccination among farm workers,” the CDC stated.

The agency recommended that people avoid exposure to sick or dead animals as well as animal waste, unpasteurized milk, bedding, and any materials that have come in contact with animals with confirmed or suspected flu.

The federal agency also advised people to consume only pasteurized milk.

In July, the Colorado Department of Agriculture instituted mandatory surveillance for all commercial cow dairies in the state licensed by the region’s Department of Public Health and Environment.

“We have seen devastating impacts of this disease not only to our dairy industry, but our poultry industry as well,” Dr. Maggie Baldwin, Colorado state veterinarian, said at the time.

“With the strong support of the dairy and poultry industries, we feel that this is the best next step in order to protect these vital industries in our state.”