California now has 15 confirmed cases of bird flu in humans, all of them dairy farm workers, up from the previous count of 13, said the state Department of Public Health on Wednesday. “While the risk to the general public remains low, additional human cases of bird flu are expected to be identified and confirmed in California among individuals who have contact with infected dairy cattle.”
With the new cases, California accounts for more than half of the 29 infections confirmed in five states since late March. The Washington Department of Health said that four poultry workers were treated for bird flu over the weekend and that samples were sent to the CDC for confirmatory tests, which could increase the U.S. total to 33 human cases.
To date, the infections appear to be the result of exposure to infected animals, and tests have not found mutations in the avian flu virus that would make it spread between people.
Outbreaks of bird flu in dairy cattle have been identified in 334 herds in 14 states. California, the No. 1 dairy state, has had the most infected herds, 134.
In the weeks after bird flu was identified for the first time in dairy cattle, state and livestock industry officials argued for, and won, a less stringent regulation than the USDA originally considered on the interstate shipment of milk cows, reported Reuters. The regulation requires dairy farmers to test lactating cows for bird flu at least seven days before shipping them across state lines. It is the only federal regulation aimed at preventing transmission of the virus.
Initially, the USDA considered requiring a test showing cattle were free of bird flu no more than three days before transport. The longer time span between testing and shipping “potentially contributed to transmission of the disease across state lines,” said the news agency.