Avian Bird Flu | IAS GYAN

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Context

A bottlenose dolphin found dead in a Florida canal in the spring tested positive for a highly virulent strain of bird flu.

Details

This version of the virus, which has spread widely among North American and European birds, has affected an unusually broad array of species. But these findings represent the first two documented cases in cetaceans, a group of marine mammals that includes dolphins, porpoises and whales.

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 infects 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 proteinson 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)

Risk groups

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 rareand 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.