Avian flu is spreading through Central Valley dairies. Is human-to-human transmission likely?

For months the avian flu, once thought to be only a problem for wild birds and poultry, has spread its way through the nation’s dairies, making cows and workers sick.

In California, the leading milk producer in the U.S., the insidious virus has hit hard, infecting 110 livestock herds, and 11 dairy dairy workers, according to the Centers for Disease Control and Prevention.

Given the size of California’s dairy industry, more than 1,100 dairies located mostly in the San Joaquin Valley, it is likely the numbers of infected cows and workers will grow.

Despite the expected surge, public health officials have said the risk to the public is low.

Could that change and develop into the next pandemic?

Scientists with the CDC along with the California Department of Public Health are tracking that possibility. What is known is that mutations happen in viruses and accumulate with continued spread from human to human.

The mutations result in variants that may have different attributes, including resistance to medication or becoming more contagious.

Although there is no evidence that the human avian flu has spread from human to human, experts are closely watching for any changes through a testing process known as genomic sequencing.

State Epidemiologist Dr. Erica Pan said that by identifying the genetic material, or genotype of an organism, scientists can examine if any mutations have happened.

“By keeping an eye on it, we can tell if it is responding to treatment, or not,” she said.

People infected with human bird flu are given medication to treat influenza and the results have been positive, Pan said.

She added that human avian flu is not new. It has been around globally for more for than 20 years with sporadic human cases.

“I am reassured that in the last 20 years we have not seen very many different variations,” Pan said.

County health officials are also working on tracking the virus among dairy workers who have become infected.

Tulare County is home to at least two dairy workers who tested positive for avian flu.

Carrie Montero, spokeswoman for the Tulare County Public Health Department, said the county did contact tracing with those living in the worker’s household and no one was showing symptoms.

In preparation for more cases of human avian flu, the CDC provided the state with 5,000 additional doses of seasonal flu vaccine for farmworkers.

A spokesman for the state health department said the agency is in the process of coordinating with county health departments with high numbers of farm and dairy workers.