According to a Sept.6 news release, CDC has confirmed a human case of avian influenza A(H5) ("H5 bird flu") reported by the state of Missouri. The case was identified through that state's seasonal flu surveillance system. The specimen was forwarded to CDC for confirmatory testing per usual protocols and confirmed yesterday. An investigation into the potential exposure is ongoing by the Missouri Department of Health and Senior Services (DHSS).
The news release says that “Missouri DHSS reports that the patient, who was hospitalized, had underlying medical conditions, was treated with influenza antiviral medications, subsequently discharged, and has recovered. There is no immediate known animal exposure. No ongoing transmission among close contacts or otherwise has been identified.”
This case marks the 14th human case of H5 reported in the U.S. during 2024 and the first case without a known occupational exposure. Additionally, this is the first time the country’s national flu surveillance system has detected a case of H5.
CDC says it will continue to closely monitor available data from influenza surveillance systems, particularly in affected states.
Identification of the neuraminidase (the "N") in the patient specimen is pending further sequencing. Attempts to sequence the genome of the virus also are underway at CDC.
The news release concluded by saying that “Based on available data, CDC's current assessment is that the risk to the general public from H5N1 remains low. CDC's recommendations related to H5 virus have not changed at this time. As always, circumstances may change quickly as more information is learned. The results of this investigation will be particularly important in light of the current lack of an obvious animal exposure. It is important to note that, while rare, there have been novel influenza A cases where an animal source cannot be identified. The main concern in these situations is that no onward transmission is occurring. Findings from the ongoing investigation will inform whether guidance changes are needed.”
