A Louisiana resident infected with H5N1 bird flu has died, authorities there reported Monday. This marks the first U.S. death from the disease.

According to the Louisiana Department of Health, the patient is an individual over the age of 65 with underlying medical conditions. He is believed to have come into contact with non-commercial and wild birds infected with the virus. The person’s name and gender were not revealed.

The news confirmed what many experts fear: that if the disease spreads unchecked, it has the potential to cause serious illness and death.

“This is an unfortunate reminder that H5N1 continues to have the ability to cause serious illness and death. “It would be wrong to be reassured by the fact that the patient had underlying health conditions,” said Jennifer Nuzzo, director of the Pandemic Center at Brown University in Providence, Rhode Island

Nuzzo noted that a child in Canada also became seriously ill with the virus but ultimately survived. However, the efforts doctors made to keep the child alive – daily blood transfusions, intubation and extracorporeal membrane oxygenation, a life-support technique that temporarily takes over the function of the heart and lungs in patients with severe heart or lung disease – illustrate the point exceptionally serious number of diseases that the virus can cause.

“This is why we need to take all infections seriously and work harder to prevent them,” Nuzzo said.

Before the H5N1 bird flu virus arrived in North America in 2021, the disease was known to have the potential to cause severe illness and death.

H5N1 was first identified in wild geese in China in 1996 and soon spread among birds in Asia, jumping to humans hundreds of times along the way. More than half of the known infections were fatal.

But since the outbreak in U.S. dairy and poultry herds, the vast majority of cases have been mild – with most patients and health care providers reporting conjunctivitis and mild shortness of breath as the most common symptoms.

According to the Centers for Disease Control and Prevention, 66 people in the U.S. have been infected with the virus — and almost all of them were exposed to the virus while working with infected dairy cows or poultry. Only two cases were acquired from an unknown source, including a child in Alameda County, California.

The only serious case so far has been the death in Louisiana.

In a statement, the CDC said the risk to the public remains low.

Yohishiro Kawaoka, a virologist at the University of Wisconsin-Madison and the University of Tokyo, said the death “shows the need for vigilance to avoid contact with the virus if possible.”

At the same time, however, Kawaoka said it was “important to note that the individual was over 65 years of age and had underlying health conditions that may have contributed to the severity of the illness.”

He said the greatest risk comes from strains circulating in cattle populations.

The virus has been detected in more than 900 dairy herds nationwide and 701 in California.

Richard Webby of the World Health Organization said local, state and federal wildlife and health agencies need to “sample more birds, interview more exposed people and learn as much as possible about this virus and where it is headed.”

“We also need to ensure that public health testing and treatment capacity is where it should be. Although it is a virus that is still low in contagiousness to humans, we should not forget the threat,” said Webby, who leads the WHO Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds.

There is no evidence that the virus has acquired the ability to transmit between people. But researchers say the more opportunities it has to spread uncontrollably through the environment and into people, the greater the chances it has of developing the mutations it needs to do so.

Rick Bright, a virologist and former head of the U.S. Biomedical Advanced Research and Development Authority, said the health status and age of the Lousiana victim are critical factors to consider when assessing the disease’s potential for harm.

“It is important to understand that almost every American over 50, especially over 65, can easily be diagnosed with an underlying medical condition,” he said.

Bright expressed concern that the virus may be changing so quickly that it could outpace traditional vaccine development and technology.

“The CDC will hopefully carefully review this case to consider updating the risk assessment and vaccine composition,” he said, underscoring the need for local, state and federal authorities to provide genetic sequencing data on this case and the birds the person was exposed to was suspended, publish too.