Another health care worker who was exposed to a Missouri patient who tested positive for bird flu developed respiratory symptoms but wasn't tested for the flu, U.S. health officials reported Friday.

Missouri healthcare worker who had contact with a hospitalized patient infected with bird flu developed mild respiratory symptoms but was not tested for the virus, U.S. officials said on Friday.

Three people in contact with a hospitalized bird flu patient in Missouri have developed symptoms, officials said.

A close contact of someone with bird flu became ill on the same day, the C.D.C. reported. But the second person was not tested, and the cause of the illness is unknown.

A third close contact of a patient in Missouri who was hospitalized with H5N1 bird flu has reported that they also experienced symptoms, the US Centers for Disease Control and Prevention said Friday.