In December 2024, the United States confirmed its first severe human case of H5N1 avian influenza in Louisiana. The patient, who had been exposed to sick and dead birds in a backyard poultry flock, was hospitalized with serious respiratory symptoms.
Key Highlights:
- First Severe U.S. Case: This marks the first severe human case of H5N1 in the United States, following 60 milder cases earlier this year.
- Source of Infection: The patient likely contracted the virus through direct contact with infected backyard poultry, not linked to commercial poultry operations.
- Virus Genotype: Genetic analysis identified the virus as the D1.1 genotype, prevalent among wild birds and poultry in North America.
- Public Health Risk: The Centers for Disease Control and Prevention (CDC) maintains that the risk to the general public remains low, with no evidence of human-to-human transmission.
H5N1 avian influenza, commonly known as bird flu, primarily affects birds but can infect humans through direct contact with infected animals or contaminated environments. Since its emergence, H5N1 has caused over 900 human infections globally, with a mortality rate exceeding 50%. In the U.S., human cases have been rare and typically mild until this recent severe case in Louisiana.
The patient, whose identity remains confidential, developed severe respiratory illness after exposure to sick and dead birds in a backyard flock. This case is notable as it is the first in the U.S. linked to non-commercial poultry exposure. Genetic sequencing revealed that the virus belongs to the D1.1 genotype, similar to strains found in wild birds and poultry across the U.S. and Canada.
Upon confirmation of the case, the CDC, in collaboration with Louisiana health authorities, initiated measures to prevent further transmission. These include monitoring individuals who had close contact with the patient and conducting surveillance in local bird populations to assess the spread of the virus. The CDC continues to advise that the risk to the general public is low, emphasizing that there is no evidence of human-to-human transmission of H5N1 in the U.S.
Health officials recommend that individuals avoid direct contact with sick or dead birds and ensure proper hygiene when handling poultry. Backyard poultry owners are advised to implement biosecurity measures to protect their flocks and themselves. The CDC also suggests that people involved in poultry farming or processing should use personal protective equipment and follow safety protocols to minimize the risk of infection.
The confirmation of the first severe H5N1 case in the U.S. underscores the importance of vigilance in monitoring avian influenza. While the risk to the general public remains low, adherence to recommended preventive measures is crucial to prevent potential transmission. Ongoing surveillance and research are essential to understand the virus’s behavior and to develop effective strategies to mitigate its impact on public health.
