There’s Hope That a Human Bird Flu Pandemic Won’t Occur

The big anxiety connected with bird flu is the development of a mutated virus that can easily be transmitted from human to human. So far, that hasn’t happened, in spite of a hundred or so human bird flu infections with the H5N1 virus. But if such a mutation occurs, a human pandemic will follow.

The recent news is that cells from the human respiratory tract show a simple anatomical difference that make such a jump difficult. Most human flu strains infect cells high in the respiratory tract (larynx, trachea, or bronchus) while avian flu strains seems to prefer deeper-lying lung cells. This makes it harder (i.e. it’s farther) for the bird flu virus to gain entry, compared to existing human flu strains. This may explain why most human bird flu cases have occurred in people working closely with infected birds, and human-to-human transmission has, so far, been rare. And why, in addition, human infections have proved to be very serious, with a high death rate – the virus can multiply very readily in lung tissue.

Of course, pessimists will figure out that it will only take a mutation in the virus to allow it to attach to the human larynx-trachea-bronchus receptors, and we’ll be at the alarming higher risk for infection and spread of human bird flu.