First severe case of H5N1 bird flu in the United States confirmed

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A Louisiana patient has been hospitalized with a severe case of avian influenza A(H5N1) virus (“H5N1 bird flu”) infection. According to the Centers for Disease Control and Prevention (CDC), this marks the first instance of severe illness linked to the virus in the United States.

Partial viral genome data of the H5N1 avian influenza virus that infected the patient in Louisiana indicates that the virus belongs to the D1.1 genotype related to other D1.1 viruses recently detected in wild birds and poultry in the United States. This H5N1 bird flu genotype is different than the B3.13 genotype detected in dairy cows, sporadic human cases in multiple states and some poultry outbreaks in the United States. At press time, additional genomic sequencing and efforts to isolate virus from clinical specimens from the patient in Louisiana are underway at CDC.

While an investigation into the source of the infection in Louisiana is ongoing, it has been determined that the patient had exposure to sick and dead birds in backyard flocks. Avian influenza A(H5N1) virus infection has previously been associated with severe human illness in other countries during 2024 and prior years, including illness resulting in death. No person-to-person spread of H5 bird flu has been detected. This case does not change CDC’s overall assessment of the immediate risk to the public’s health from H5N1 bird flu, which remains low. However, for pest management professionals (PMPs), it’s a good reminder to wear appropriate personal protective equipment (PPE) and take serious precautions to avoid possible exposure while doing any pest control at poultry and dairy accounts or at residential accounts where there are backyard chickens present.  Similar precautions should be taken at all bird control and exclusion accounts.

CDC reports the best way to prevent H5 bird flu is to avoid exposure whenever possible. Infected birds shed avian influenza A viruses in their saliva, mucous and feces. Other infected animals may shed avian influenza A viruses in respiratory secretions and other bodily fluids, such as in unpasteurized cow milk, also known as “raw milk,” the organization says.

For more information regarding avian flu, read these prior reports: