Bird Flu Mutating Rapidly: Experts Warn After First US Death
Scientists have raised alarm bells after the first H5N1 death in the US was reported in January 2025, following exposure to infected chickens.
Researchers have identified nine mutations in a bird flu strain in another infected person in Texas, US.
This strain has shown a high ability to cause disease, with a higher ability to replicate in the brain. The good news, however, is that the current antiviral treatments are still effective against the strain.
The researchers, from the Texas Biomedical Research Institute (Texas Biomed), published their detailed findings in the journal Emerging Microbes & Infections. After conducting experiments on mice, they revealed that the new strain has become quite adept at replicating in human cells, causing severe disease, and was found in much higher quantities in brain tissue.
The strain was compared to one found in dairy cattle, that has been spreading havoc across the US, UK and several countries.
“There are nine mutations in the human strain that were not present in the bovine (cattle) strain, which suggests they occurred after human infection,” Dr Martinez-Sobrido said.
The study showed that the strain known as rHPhTX developed changes that make it better at spreading, triggering inflammation, and causing disease in mice.
According to the authors, these changes could increase the risk of the viruses spreading in humans. Initially, bird flu did not show transmission to humans but only affected animals.
“As a result, human H5N1 strains must be closely monitored and assessed for their public health risk, and efforts should be made to eradicate the H5N1 from cows, in order to avoid further human H5N1 infections by these already mammalian adapted H5N1 viruses,” the authors wrote in the study.
The researchers also tested several FDA-approved antiviral medicines on both virus strains in cells and found that the mutations did not impact the effectiveness of the drugs.
This means that the current medications are effective against the mutations of the H5N1 strain.
They added that antivirals could be the first line defense against bird flu in humans before vaccines are widely available. Another study published in December 2024, revealed that antiviral medicines can help since humans don’t have any immunity against H5N1 and seasonal flu vaccines have limited protection.