"Even sporadic cases of human-to-human transmission indicate a big change in the virus and suggest it is exploring new ...

Hospital workers reported respiratory symptoms after encountering a Missouri patient with H5N1 who had not been exposed to ...

The latest developments are highly concerning, as they raise the possibility that the H5N1 virus has evolved the ability to ...

Further testing could confirm whether the patient, who has since recovered, actually had bird flu despite testing positive.

U.S. health officials have run into obstacles in their efforts to determine whether a Missouri person infected with H5N1 bird ...

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

The CDC said an investigation into a human H5N1 bird flu infection in Missouri has found four additional health care workers ...

In what could be the first cases of bird flu spreading between humans in the United States, a group of potential H5N1 ...

Chances are low that human-to-human spread of bird flu occurred in a group of people who were exposed to a patient infected ...

Seven people fell ill with flu-like symptoms after contact with someone infected with H5N1, raising fears that the virus has ...

More than a month after a person in Missouri mysteriously fell ill with H5-type bird flu, investigators in the state are ...

Four more health-care workers who tended to a person hospitalized with H5N1 bird flu have revealed that they had respiratory ...