First U.S. H5N1 Bird Flu Death Reported in Louisiana Amid Low Overall Risk

• The first U.S. death from H5N1 avian influenza has been reported in Louisiana, involving an individual over 65 with underlying conditions who had exposure to backyard poultry.
• Of 954 global H5N1 cases tracked by WHO since 2003, 48.6% resulted in death, while the U.S. has documented only 58 confirmed cases across eight states.
• CDC analysis confirms the virus remains primarily bird-to-human transmission with no evidence of human-to-human spread, maintaining a low public health risk despite isolated cases.

The Louisiana Department of Health has reported the first U.S. death from H5N1 avian influenza, marking a significant development in the surveillance of bird flu cases nationwide. The deceased patient, aged over 65 with underlying medical conditions, contracted the virus after exposure to noncommercial backyard flock and wild birds in December.

The Centers for Disease Control and Prevention (CDC) confirmed the H5N1 infection on December 18, following the patient's hospitalization. Genetic analysis of the virus samples revealed slight mutations from the original avian strains, though these changes occurred after infection and maintain the same D1.1 genotype.

Current U.S. Surveillance Data

The U.S. has documented 58 confirmed cases of H5N1 as of December 2024, with state distribution as follows:

• California: 37 cases
• Washington: 11 cases
• Colorado: 10 cases
• Michigan: 2 cases
• Iowa, Oregon, Texas, and Wisconsin: 1 case each
• Louisiana: 1 case (fatal)

Global Context and Risk Assessment

WHO data presents a stark contrast between global and U.S. outcomes. Since 2003, the organization has tracked 954 cases worldwide, with 464 deaths representing a 48.6% mortality rate. The years 2003-2009 saw 468 cases with 282 deaths, while 2010-2014 recorded 233 cases and 125 deaths.

Transmission Patterns and Risk Factors

The CDC emphasizes that the overall health risk to the general public remains low. Key findings include:

• No documented person-to-person transmission in the U.S.
• Primary transmission occurs through close contact with infected birds
• Highest risk groups include poultry workers and those with occupational exposure
• Current virus strains show compatibility with existing candidate vaccine viruses

Broader Animal Impact

While human cases remain limited, the virus has shown significant presence in animal populations:

• Multistate outbreak among dairy cattle
• Widespread infections in wild bird populations
• Sporadic cases in poultry and other mammals
• California reports the highest human exposure incidents (34) linked to commercial agriculture

The CDC continues to monitor the situation closely, particularly focusing on any virologic changes that could increase human transmission risk. Current evidence suggests that while mutations can occur, the virus has not developed characteristics for efficient human-to-human spread.