Blood tests of several people who were in contact with a patient in Missouri who caught H5N1 bird flu without any known exposure to infected animals reveal that at least one of them — a person who lived in the same house and had symptoms at the same time — also had the virus, according to two sources with knowledge of the investigation.
H5N1 is a type of influenza that’s rare in humans but is highly contagious and deadly in several species of animals, including poultry and dairy cattle, raising fears that it could mutate and become a virus that preys on people, too.
The specialized blood tests, which were conducted by scientists at the US Centers for Disease Control and Prevention in Atlanta, looked for immune proteins called antibodies made in response to an infection. These antibodies confirm that a person has had an infection with a particular pathogen. The results were shared more widely with public health officials, scientists and the media in several calls hosted by health officials on Thursday morning.
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