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.

A routine flu screening in late summer found the H5N1 virus in a Missouri patient. Unlike the other reported cases of avian flu, this person did not report being in recent contact with animals.

Chances are low that human-to-human spread of bird flu occurred in a group of people who were exposed to a patient infected with the virus in Missouri, US health authorities said.

Health officials in California are investigating a possible third human case of bird flu, the California Department of Public Health announced Saturday.

Kern County Public Health announced an ongoing investigation Saturday into a person who possibly came in contact with a cow infected with bird flu. An individual working at a dairy farm has potentially been infected with H5N1 bird flu after coming in contact with a cow carrying the virus,

The Centers for Disease Control and Prevention should have results later this month that provide more insight into how a Missouri resident, who hadn’t had any contact with infected animals or food, contracted a case of highly pathogenic avian influenza.