The Centers for Disease Control and Prevention (CDC) recently reported that genetic sequences of H5N1 bird flu viruses collected from a severely ill patient in Louisiana showed signs of developing mutations that could affect the virus’s ability to attach to cells in the upper airways of humans. One of these mutations was also found in a virus sample taken from a teenager in British Columbia who was in critical condition after contracting H5N1.
The mutation observed in both viruses is believed to help H5N1 adapt to bind to cell receptors found in human upper respiratory tracts. Typically, bird flu viruses attach to cell receptors that are rare in human airways, which is why H5N1 does not easily infect humans and does not spread between people.
Professor Scott Hensley from the University of Pennsylvania’s Perelman School of Medicine noted that the mutations in these severe cases raised concerns. However, he cautioned against reading too much into data from just two cases. The CDC’s report indicated that the mutations observed in the Louisiana patient’s samples likely developed during the course of the infection, rather than being transmitted at the time of infection.
Virologist Angela Rasmussen emphasized the importance of reducing human infections to prevent the emergence of a pandemic H5N1 virus. The ongoing outbreak of H5N1 in dairy cows has led to 65 confirmed cases of human infection in the United States this year. Most cases were linked to contact with infected cows or poultry, with two cases having unknown sources of infection.
The viruses circulating in cows differ slightly from those in wild birds and poultry farm outbreaks. The Louisiana and British Columbia cases were caused by genotype D1.1 viruses, with no other severe infections reported in North America in 2024. Research is ongoing to determine whether the mutations observed in these cases increase the virus’s ability to bind to human cells and potentially lead to easier transmission between people.
The current condition of the Louisiana patient is unknown, and updates on their status have not been provided. Hensley’s laboratory is conducting tests to assess the impact of the mutations on the virus’s ability to bind to human cells. While attachment is a crucial factor for infection, additional changes in the virus may be necessary for person-to-person transmission. The lack of onward transmission from the British Columbia teenager suggests that additional mutations or factors are needed for efficient spread of the virus. The state of Louisiana has reported that there have been no secondary cases among contacts of the person who was hospitalized with a rare virus. The Centers for Disease Control and Prevention (CDC) is currently working with the Louisiana Department of Public Health to conduct genetic sequencing of samples taken later in the person’s infection. This process will help determine if any additional mutations developed in the virus.
The CDC’s collaboration with the state health department is crucial in monitoring and understanding the spread of the virus. By analyzing genetic sequences, health officials can track any changes in the virus and identify potential sources of transmission. This information is essential for implementing effective public health measures to prevent further spread of the virus.
It is reassuring to know that there have been no secondary cases identified so far among contacts of the hospitalized individual. This indicates that the virus may not be easily transmissible between people. However, continued monitoring and genetic sequencing are necessary to ensure that any potential outbreaks are quickly identified and contained.
In a correction to an earlier version of this article, it was noted that the genotype of the H5N1 virus circulating in cows was misstated. It is important to provide accurate information to the public to prevent misinformation and confusion surrounding public health issues.
Overall, the collaboration between the CDC and the Louisiana Department of Public Health is essential for tracking and understanding the rare virus. By conducting genetic sequencing and monitoring contacts of the hospitalized individual, health officials can effectively prevent the spread of the virus and protect public health.
