Hospital workers reported respiratory symptoms after encountering a Missouri patient with H5N1 who had not been exposed to farm animals. Officials say bird flu transmission is unlikely.

In what could be the first cases of bird flu spreading between humans in the United States, a group of potential H5N1 infections in Missouri has now grown to eight.

Missouri officials are under growing pressure from national public health experts to pinpoint the source of the state’s first human bird flu infection.

Two dairy workers in California have been infected with the state’s first human cases of bird flu, federal and state health officials said. The late Thursday announcement of two confirmed

California said on Thursday it confirmed a fourth human case of bird flu in a person who had contact with infected dairy cattle. All four people who have tested positive for the virus in the most populous U.

While California reports more human cases of bird flu, experts say the true number of cases could be much higher

U.S. and California health officials confirmed two new cases of H5N1 bird flu in dairy farm workers in the state on Friday, bringing the total of infected dairy workers in that state to six, and the total of human cases nationwide this year to 20.

The Centers for Disease Control and Prevention said Thursday California has confirmed a third human case of H5 bird flu. All three confirmed cases had occupational exposure to infected dairy cows.