The US Centers for Disease Control and Prevention (CDC) has reported the first serious case of the H5N1 bird flu virus in the country, after a patient was hospitalized in Louisiana.
Partial data from the viral genome of the H5N1 bird flu virus that infected the Louisiana patient indicate that the virus belongs to the D1.1 genotype, related to other D1.1 viruses recently detected in wild and poultry birds in the United States and in recent human cases in Canada and Washington State.
This H5N1 bird flu genotype is different from the B3.13 genotype detected in dairy cows, in sporadic human cases in several states, and in some outbreaks in poultry in the United States. CDC says it is conducting additional genomic sequencing and efforts to isolate the virus from clinical samples from the Louisiana patient.
Although the source of the infection in Louisiana is still being investigated, it has been determined that the patient was exposed to sick and dead birds raised by the patient, making this the first case of H5N1 avian influenza in the US linked to exposure to poultry.
CDC notes that with this case, in addition to the affected commercial poultry and dairy operations, “wild birds may also be a source of exposure.” Therefore, it warns that “people with occupational or recreational exposure to infected animals are at increased risk of infection and should follow recommended precautions when around animals infected or potentially infected with the H5N1 avian influenza virus.”
According to CDC, the best way to prevent H5 avian influenza is to avoid exposure. In this regard, they recall that infected birds shed avian influenza A viruses in saliva, mucous membranes, and feces. In addition, other infected animals can shed avian influenza A viruses in respiratory secretions and other body fluids (for example, in unpasteurized cow’s milk or raw milk).
Since April 2024, a total of 61 human cases of H5N1 avian influenza have been reported in the United States. This case does not change CDC’s overall assessment of the immediate public health risk of H5N1 avian influenza, which remains low.
