Bird flu has ‘mutated’ and may spread easier among humans via coughing after two severe cases detected [Video]

H5N1 bird flu from an extreme case in the US has mutated to attach to human upper airway cells, health chiefs have warned.

The case, spotted this month in a hospitalised Louisiana man, is the first “severe” bird flu case in the US amid its rapid spread through cows this year.

In nearby Canada, a healthy teenage boy was admitted to intensive care after contracting the same strain in October.

The new US case, like the one in Canada, is believed to have caught the virus directly from birds in his backyard, not through infected cattle.

Tests show both cases involve a mutated version of H5N1 that helps it bind to human upper respiratory cells.

This could make it easier to spread between people through coughing or sneezing, raising concerns the virus is adapting to infect humans more effectively.

Bird flu viruses do not typically bind to a cell …