By Apoorva Mandavilli and Emily Anthes
A patient from Louisiana, who had been admitted with severe avian flu, has passed away, representing the first fatality of its kind in the United States, as confirmed by state health officials earlier this week.
The individual was over 65 years old and had pre-existing health issues, according to the officials. The person contracted the H5N1 avian flu virus after coming into contact with a backyard flock and wild birds.
There is no evidence suggesting that the virus is transmitting from person to person anywhere in the nation, and Louisiana officials have not found any additional cases in the state. Pasteurized dairy items continue to be safe for consumption.
“I still believe the risk is low,” stated Dr. Diego Diel, a virology expert at Cornell University.
“However, it’s crucial for people to remain cautious and steer clear of sick animals, ill poultry, sick dairy cattle, and wild birds,” he continued.
This report comes following findings that virus samples from the patient exhibited mutations that could enhance its ability to infect humans.
The Centers for Disease Control and Prevention indicated late last month that these mutations were absent in samples from the backyard flock, implying they evolved in the patient as the illness advanced.
One of these mutations was also detected in a virus sample from a 13-year-old girl in Canada who required hospitalization and respiratory support. She has since recovered.
Both individuals harbored a strain of the virus that is currently circulating among wild birds, which is separate from that causing the outbreak in dairy cattle.
While these are singular instances, experts have pointed out that they highlight the potential for the virus to evolve into more dangerous variants.
The situation “serves as a reminder that H5N1 influenza has been and remains a perilous virus,” remarked Dr. James Lawler, a director at the University of Nebraska’s Global Center for Health Security.
“The broader the virus circulation, especially with human infections and in other mammals, the greater the likelihood that the virus will acquire mutations adapting it for human disease and transmission,” he stated. “This presents a risk for everyone.”
This risk escalates particularly as the country faces a challenging flu season.
An individual infected with both the avian flu and the seasonal flu could provide H5N1 with ample opportunity to develop the mutations necessary for effective human transmission.
H5N1 has been circulating among wild birds for several years and has affected dairy cattle for nearly a year. The outbreak shows no signs of waning, impacting more than 900 herds across 16 states. The virus has also spread from dairy farms to poultry operations, remaining prevalent in wild bird populations.
In December, California, the state most severely impacted by the cattle outbreak, declared a public health emergency.
At least 66 people have been diagnosed with the virus in the United States in 2024, according to the CDC. Almost all cases have involved individuals who worked on farms with infected cows or birds.
Most individuals have experienced mild symptoms, typically conjunctivitis, also known as pink eye, alongside respiratory issues. Globally, approximately 500 fatalities have been reported over the last two decades, the majority occurring in Southeast Asia.
The Louisiana patient was noted to have been hospitalized last month. However, state officials have opted not to disclose further information, citing patient confidentiality.
Prior to the last year, only one case of human H5N1 infection had been documented in the U.S. — a poultry worker in Colorado in 2022.
Experts have advised against consuming raw milk, which might contain elevated levels of the virus. Though no human cases have been linked to raw milk so far, there have been instances of cats in various states dying after ingesting milk contaminated with the virus.
