Human bird flu cases ’an enormous concern’: WHO flags surge in H5N1 cases with ‘extraordinarily high’ mortality

The World Health Organization has voiced concern as bird flu or avian influenza continues to cross the species barrier with increasing frequency. The UN health body said on Thursday that the (H5N1) strain has become “a global zoonotic animal pandemic” with human victims displaying an “extraordinarily high” mortality rate. The current bird flu outbreak began in 2020 and has led to the deaths of tens of millions of animals. 

“The great concern of course is that in... infecting ducks and chickens and then increasingly mammals, that virus now evolves and develops the ability to infect humans and then critically the ability to go from human to human,” said WHO chief scientist Jeremy Farrar.

CDC data indicates that the outbreak first began in early 2020 at commercial turkey farms in the US. Since then it has also affected wild birds as well as land and marine mammals. Cows and goats joined the list last month — a surprising development for experts because they were not thought susceptible to this type of influenza.

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Over the years there have been some rare cases where bird flu viruses — primarily avian influenza A(H7N9), the highly pathogenic avian influenza (HPAI) A(H5N1) and A(H5N6) — have affected humans. 

“Infected birds shed avian influenza viruses through their saliva, mucous and feces. Other animals infected with avian influenza viruses may have virus present in respiratory secretions, different organs, blood, or in other body fluids, including animal milk. Human infections with avian influenza viruses can happen when virus gets into a person’s eyes, nose or mouth, or is inhaled,” the CDC explains on its website. 

Is H5N1 contagious between humans?

There is no evidence that currently suggests the influenza A(H5N1) virus is spreading between humans. Farrar however noted that there have now been hundreds of cases where humans have been infected through contact with animals — where “the mortality rate is extraordinarily high”.

Between 2003 and April 1 this year, WHO reported 463 deaths from 889 human cases across 23 countries. This puts the case fatality rate at 52%.

(With inputs from agencies)