None of the health care workers or other contact have tested positive for avian flu antibodies so far — but could their illness signal human-to-human transmission?

By Julie Steenhuysen (Reuters) -Four additional healthcare workers in Missouri who came in contact with a hospitalized bird flu patient developed mild respiratory symptoms but the virus was not confirmed in any of them,

Four more health-care workers who tended to a person hospitalized with H5N1 bird flu have revealed that they had respiratory symptoms after their exposures, according to the US Centers for Disease Control and Prevention.