Small genetic changes may assist the bird flu virus in gaining entry into cells in the upper respiratory tract, according to the C.D.C. However, there is no evidence that mutations are common in nature. After an individual in southwest Louisiana was hospitalized with a serious case of bird flu, the first reported instance of such illness in the United States, health workers took samples from the person’s nose and throat to search for genetic information about the virus. On Thursday, federal health officials disclosed some troubling findings. Certain genetic samples included mutations that could potentially enhance the ability of the H5N1 bird flu virus to infect humans. One of these mutations was noted last month in a viral sample collected from a teenager in British Columbia, Canada, who had a severe case of bird flu. The teenager was put on a ventilator during an extended hospital stay. While severe cases are concerning, scientists noted some positive aspects in the new report about the Louisiana patient. Specifically, the mutations appeared to occur as the virus adjusted to its human host. The Centers for Disease Control and Prevention stated that the genetic changes were absent in H5N1 samples from the backyard poultry flock that infected the patient. This indicated that the viruses in the environment had not yet developed the troubling mutations. Nonetheless, each new human case presents H5N1 with more chances to adjust to humans, which could increase its ability to transmit between individuals. We are experiencing difficulties accessing the article content. Please enable JavaScript in your browser settings. Thank you for your patience as we confirm access. If you are using Reader mode, please exit and sign into your Times account, or subscribe to access all of The Times. Thank you for your patience as we check your access. Are you already a subscriber? Sign in.. Interested in accessing all of The Times?
