A person in Missouri has become the first case in the United States of H5 avian influenza without a known exposure to sick or infected animals, according to the US Centers for Disease Control and Prevention (CDC). This case marks the 14th reported human infection with H5 avian influenza in the U.S. for 2024 and is notable for being identified through the national flu surveillance system, rather than through targeted animal surveillance.
The patient, who had underlying medical conditions, was hospitalized on August 22 and subsequently tested positive for influenza A. The individual received antiviral treatment and has since recovered and returned home, as reported by the Missouri Department of Health and Senior Services (MDHSS).
A sample from the patient was sent to the CDC, which confirmed the presence of H5 avian influenza. The specific strain’s neuraminidase (N) type has not yet been identified. The CDC is currently working on isolating the virus and analyzing its genetic sequence to determine how closely it is related to viruses causing ongoing outbreaks in birds and other mammals in the U.S.
The CDC has noted that there are no current cases of bird flu in cattle in Missouri, though poultry outbreaks have been reported in the state. Despite the confirmation of this case, the CDC’s risk assessment for H5N1 avian influenza for the general public remains low. The agency continues to monitor the situation and will provide updates as more information becomes available.
