By Leah Douglas
(Reuters) - Human bird flu cases in California may be undercounted as farm workers avoid testing due in part to economic concerns, according to a labor union and a state expert.
Since early October, bird flu has infected 15 dairy farm workers in California, where the virus has rapidly spread since August to more than 130 dairy herds.
California farm workers with symptoms consistent with bird flu have avoided testing because they fear they would need to isolate at home without pay, said Elizabeth Strater, national vice president of the United Farm Workers labor union.
"There is a very significant undercount of cases because we don't have a way to monitor who is sick because workers are unwilling to test," Strater said.
The symptoms associated with human cases of the virus, like fever and conjunctivitis, are not severe enough to risk the loss of income, Strater added.
People who test positive for bird flu must isolate until public health officials have determined they no longer pose a spread risk, according to guidance from the California Department of Public Health.
Erica Pan, California's state epidemiologist, acknowledged there is a possibility of an undercount among workers.
"People that have milder symptoms may not be coming forward for testing," Pan said.
The state is working with a multilingual team from the U.S. Centers for Disease Control and Prevention in California's Central Valley, where most of the cases have been, to investigate human infections of the virus, Pan added.
Farm workers who contract avian flu on the job are eligible for worker's compensation, said a spokesperson for the California Department of Industrial Relations.
The CDC is spending $5 million on a seasonal flu vaccine push to farm workers, hoping to reduce the risk that a worker would simultaneously contract bird flu and seasonal flu, which could lead to virus mutations that might enable it to spread more easily.