- 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.
What is bird flu?
- 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, 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.
Bird flu: Infection in humans
- 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.
Symptoms of avian influenza
- Fever, cough, sore throat, muscle aches, nausea, abdominal pain, diarrhea, vomiting
- Severe respiratory illness
- Neurologic changes (altered mental status, seizures)
- Children and adults below 40 were seen to be the most affected and mortality was high in 10-19 years olds.
Bird flu: Human-to-human transmission
- 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 then people working closely with poultry must take precautionary measures and maintain proper personal hygiene.
- Although a few isolated family clusters have been reported, transmission in these clusters may have occurred through common exposure and in rare situations a very close physical contact; there is no evidence of human-to-human transmission via small-particle aerosols.
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