On July 21, 2021 an 11-year-old boy died of H5N1 avian influenza in Delhi. This is the first recorded death due to the bird flu in India this year. In January, bird flu was confirmed in several states with thousands of birds, including migratory species, being found dead.
Bird flu or avian influenza is a disease caused by avian influenza Type A viruses found naturally in wild birds worldwide. The virus can infect domestic poultry including chickens, ducks, and turkeys and there have been reports of H5N1 infection among pigs, cats, and even tigers in Thailand zoos.
Avian Influenza type A viruses are classified based on two proteins on their surfaces – Hemagglutinin (HA) and Neuraminidase (NA). There are about 18 HA subtypes and 11 NA subtypes. Several combinations of these two proteins are possible e.g., H5N1, H7N2, H9N6, H17N10, etc.
There have been reports of avian and swine influenza infections in humans including A(H1N1), A(H1N2), A(H5N1), A(H7N9), etc. The first report of human H5N1 infection was in 1997 and currently, over 700 human cases of Asian Highly Pathogenic Asian Avian Influenza A (HPAI) H5N1 virus have been reported to the World Health Organisation from 16 countries. The infection is deadly as it has a high mortality rate of about 60%.
The most common route of virus transmission is direct contact — when a person comes in close contact with infected birds, either dead or alive.
Humans can also be affected if they come in contact with contaminated surfaces or air near the infected poultry. There is no sufficient evidence suggesting the spread of the virus through properly cooked meat.
“The transmission of the virus from birds to humans is rare and sustained human-to-human transmission of the H5N1 virus has not yet been established. But people working closely with poultry must take precautionary measures and maintain proper personal hygiene.