As for testing, the girl's first swab at BC Children's was positive for influenza A but negative for H1 or H3 disease. Further polymerase chain reaction testing for flu, COVID, and respiratory syncytial virus showed a cycle threshold (Ct) value of 27.1, suggesting a relatively high viral load, which prompted further subtyping, revealing H5 disease.

Most human cases of bird flu in North America have been mild, a fact that’s underscored by a new study of the first 46 confirmed human H5N1 infections in the United States this year. But the case of an ill Canadian teen stands out because of its severity and because the source of exposure remains a mystery.

Genetic analysis of H5N1 bird flu virus that infected a Canadian teenager shows 'worrisome' mutations, new studies reveal.

The patient in Louisiana who was hospitalized with severe bird flu illness was found to have a mutated version of the virus. Doctors react and share their concerns.

The CDC previously confirmed the first severe human case of bird flu in Louisiana, but now the CDC has confirmed a virus mutation. Find out more here

In 2024, at least 66 human cases of bird flu have been reported in the United States, each one raising the risk of another pandemic like COVID-19. So far, most cases have been described as “mild,” which means they weren't hospitalized.

As of December 30, the CDC has confirmed 66 human cases of the bird flu virus in the United States. Most of them were mild infections among dairy workers and others who had contact with infected animals.