A person in Missouri has been infected with bird flu, the Centers for Disease Control and Prevention announced on Friday. The adult, who had no history of contact with poultry or dairy cows, was hospitalized on Aug. 22 and has since recovered.
This case marks the first known case of infection in the United States in someone who had never handled poultry or dairy cows, adding to growing concerns about the risk of bird flu spreading among humans.
The CDC said the risk among the general public remains low.
According to the CDC, at least 196 dairy herds in 14 states have confirmed cases of the H5 influenza virus. Poultry infections have been confirmed in 48 states. The Missouri patient is the 15th human case of H5 reported in the United States since 2022, according to CDC data. Since the beginning of 2024, 14 poultry and dairy workers have been infected. Most had mild flu-like symptoms, such as fever and runny nose. Many also suffered from conjunctivitis and measles.
There have been no reported cases of H5 infection in dairy cattle in Missouri. Several cases have been reported in commercial poultry, home chicken flocks and wild birds.
“The question now is, how did this patient become infected?” said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center in Nashville, Tenn. “That requires a very thorough investigation.”
There is currently no evidence that H5N1, the H5 virus that is prevalent in dairy cows, is being transmitted from person to person. Samples from the Missouri patient need to be studied in a lab to see whether the H5 virus has acquired a mutation that makes it easier to transmit to people, Schaffner said.
“This is going to be very interesting,” he said.
Missouri health officials said in a separate statement that they have not seen any signs of unusual human flu activity in the state, such as increased emergency room visits or flu testing.
Missouri health officials said in a statement that samples taken from the patient were sent to the Missouri State Public Health Laboratory, which will then send them to the CDC for further testing.
According to Missouri officials, the adult patient has underlying health conditions and tested positive for influenza A. No close contacts of the patient have been found to have the virus.