On 6 September 2024, the USA notified WHO of one additional laboratory-confirmed human case of avian influenza A(H5) virus infection in an individual aged >18 years, with a history of severe underlying disease in the state of Missouri. The individual developed symptoms on 20 August 2024. Symptoms were acute in onset and included the following: chest pain, nausea, vomiting, diarrhea, and weakness. The patient was hospitalized, treated with oseltamivir and recovered from the illness. The individual reported not having contact with animals within the 10 days prior to symptom onset; however, the investigation into potential sources of exposure was ongoing at the time of reporting. A nasopharyngeal swab specimen was collected and tested by with a multiplex PCR respiratory panel at the hospital laboratory, where the specimen was positive for influenza A virus, and negative for both the A(H1) and A(H3) markers. Based on surveillance submission guidance for influenza A unsubtypable results, the specimen was forwarded to the Missouri State Public Health Laboratory (MSPHL) with the Department of Health and Senior Services where the specimen underwent further testing. The specimen was received at CDC on 4 September and confirmed to be positive for influenza A(H5) on 5 September. At the time of reporting, there was no information on the N-type or other characteristics of the virus. Genetic sequencing and virus culture were underway at the time or reporting.

 

One close contact of the patient developed symptoms of cough and tiredness the same day as the case; however, no diagnostic testing was performed, and the individual recovered from their illness without seeking medical care. This individual reported not having contact with animals within the 10 days prior to symptom onset. No additional illnesses have been reported among close contacts of the case. Case investigation and surveillance activities were ongoing by public health officials at the time of reporting.