US confirms two human bird flu cases in Washington state

WASHINGTON (Reuters) -The U.S. Centers for Disease Control and Prevention on Thursday confirmed two of the four presumptive positive bird flu cases among poultry farm workers in Washington state.

The agency also ruled out bird flu infections among healthcare workers who tended to a person who contracted the virus in Missouri, officials said in a press call.

All of the 31 confirmed U.S. human cases of bird flu but the one in Missouri have been among farm workers who had contact with infected poultry or dairy cows. Officials have said the risk to the general public from bird flu remains low.

The CDC expects the number of confirmed cases in Washington to rise as it completes confirmatory testing of additional presumptive positives, said Principal Deputy Director Nirav Shah on the call.

Serological testing of healthcare workers who came in contact with the sick individual in Missouri showed they were not infected with bird flu, a CDC official said on the call.

The agency's Missouri investigation ruled out person-to-person spread but some tests of a household contact of the sick individual suggested an infection, officials said. The agency said it suspects both people may have been exposed to a sick animal that they could not identify.

The CDC has deployed teams to California, Michigan, Colorado, and Washington to assist with its bird flu response, Shah said.

(Reporting by Leah Douglas and Ahmed Aboulenein in Washington and Julie Steenhuysen in Chicago; Editing by Bill Berkrot)