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, U.S. health officials said on Friday.

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

At least eight people may be infected with H5N1 bird flu in Missouri, marking the first cluster of the disease spreading between humans in the United States. The first case of a human contracting bird flu with no known animal contact happened in Missouri in August,

CDC said that four more healthcare workers have revealed that they had respiratory symptoms. These cases have been linked to the person who was earlier hospitalised with H5N1 bird flu in Missouri. The CDC also revealed that two other healthcare workers had been identified as having symptoms after caring for this patient,