Context
An 11-year-old boy is died of H5N1 avian influenza in Delhi. In January, bird flu was confirmed in several states with thousands of birds, being found dead.
What is Avian influenza?
- Bird flu or avian influenza is a disease which is caused by avian influenza Type A viruses found naturally in the wild birds worldwide.
- The virus can infect domestic poultry which includes chickens, ducks and turkeys.
- Avian Influenza type A viruses which are classified based on two proteins on their surfaces:
- Hemagglutinin(HA)
- Neuraminidase(NA)
- There are about 18 HA subtypes and 11 NA subtypes.
- Several combinations of these two proteins are also possible e.g., H5N1, H7N2, H9N6, H17N10, etc.
- The virus was first detected in geese in China in 1996.
- Symptoms of avian influenza: Fever, cough, sore throat, nausea, abdominal pain,muscle aches, diarrhea, vomiting Severe respiratory illness (respiratory distress, viral pneumonia, respiratory failure), Neurologic changes (altered mental status, seizures).
- Risk groups: Children and adults below 40 are seen to be the most affected and mortality was high in 10-19 years old.
How deadly is this virus?
- HPAI Asian H5N1 is deadly for poultry.
- The infection is deadly as it has a high mortality rate of about 60%.
Human Transmission of influenza
- Most common route of transmission: Direct contact
- Humans can also be affected after coming in contact with contaminated surfaces or air near the infected poultry.
- The transmission of the virus from the birds to humans is rare and sustained human-to-human transmission of the H5N1 virus has not been established yet.
- There have been reports of avian and swine influenza infections in the humans including A(H1N1), A(H1N2), A(H5N1), A(H7N9), etc.
- The first report of the human H5N1 infection was in 1997.
- Currently, over 700 human cases of Asian Highly Pathogenic Asian Avian Influenza A (HPAI) H5N1 virus have also been reported to the World Health Organisation from 16 countries.
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