NIH leaders urge action as human H5N1 cases rise in North America

Most human cases of H5N1 bird flu in North America have been mild, according to a new study of 46 confirmed infections in the U.S. this year. However, a severe case involving a Canadian teenager has raised concerns due to its unknown source of exposure. The 13-year-old girl, who had asthma and obesity, became critically ill in November and required advanced medical treatment. Health officials in British Columbia found no evidence of the virus in her environment, and no one else was infected. The new report indicates an increase in human H5N1 cases, with some infections showing changes that may allow the virus to adapt to humans. Experts are calling for improved surveillance and better reporting of animal infections to track the virus's spread.