An investigation into the still unexplained human H5N1 bird flu infection in Missouri has turned up four additional health care workers who developed mild respiratory illness symptoms after caring for the patient in hospital in August, the Centers for Disease Control and Prevention reported on Friday.
It is not clear if any of these people were actually infected with H5N1; they were not tested at the time when they were ill. But the fact that they became ill after caring for this patient raises the specter of person-to-person spread of the virus — a possibility that flu experts say needs further exploration. Testing their blood for antibodies to H5N1 should answer the question.
“CDC continues to closely monitor available data from influenza surveillance systems, particularly in affected states, and there has been no sign of unusual influenza activity in people, including in Missouri,” the agency said in the update, posted to its website.
The CDC continues to characterize the risk posed to the general public by the H5N1 outbreak as “low.”
In the more than a quarter century that H5N1 bird flu has been circulating, there have been rare occasions when it was thought that person-to-person spread had probably occurred. But ongoing chains of transmission involving several generations of cases have never been detected.
