Bird flu, also known as avian influenza, is an infectious viral disease of birds, especially wild waterfowls such as ducks and geese. It is a viral infection that primarily infects birds, including chicken, other poultry, and wild aquatic birds.
This highly-contagious disease spreads from infected birds to other winged creatures through contact with nasal, and respiratory secretions and also due to contamination of feed and water. Bird flu virus is sensitive to heat, and dies at cooking temperatures.
The first incident of bird flu infection occurred in Hong Kong in 1997.
Thousands of birds have died due to different variants of bird flu in Himachal Pradesh, Kerala, Rajasthan, Madhya Pradesh and Haryana, prompting the Centre to issue an alert to the states to monitor their health in forest areas and near water bodies.
As of January 6, 2021, avian influenza has been reported from 12 epicentres of four states - Rajasthan, Madhya Pradesh, Himachal Pradesh and Kerala - after confirmation of positive samples from ICAR-NIHSAD. “So far, no human case of Avian Influenza has been reported. Ministry of Health & Family Welfare continues to keep a strict watch over the evolving scenario,” the Centre has said.
All bird species are susceptible to the infection, but domestic poultry flocks are more vulnerable to bird flu infections that can easily reach epidemic proportions. Bird flu virus can affect several species of domestic poultry, such as chickens, guinea fowl, turkeys, quails, ducks, as well as wild migratory birds, pet birds, and waterfowls.
Pig is the only animal capable of two-way transmission of avian influenza virus between birds and humans. However, domestic species of pigs and ducks carrying and multiplying this virus do not generally die because of the virus. Chickens having little resistance against it generally succumb to heavy viral load.
Some aquatic birds act as hosts of influenza viruses by carrying the virus in their intestines and shedding it. Infected birds shed virus in saliva, nasal secretions and faeces. Avian influenza viruses spread among susceptible birds when they have contact with contaminated nasal, respiratory and faecal material from infected birds.
However, faecal-to-oral transmission is the most common mode of spread. The virus of bird flu can spread among birds through direct contact with secretions from infected birds, contaminated feed, water, equipment, and human shoes and clothing.
There are no known cases of bird flu in human beings, and the risk to general public is quite low. The disease of bird flu infects humans through the contact of sick poultry birds, and can also be transmitted from a sick person to a healthy person.
Also, the risk of transmission of bird flu is mainly for the animal handlers, and people in the close vicinity. Basically, the bird flu virus does not easily spread from person to person, according to the World Health Organization (WHO).
In humans, the common symptoms of bird flu or avian influenza ranges from typical influenza like, fever, cough, muscle aches, sore throat to eye infections, pneumonia, viral pneumonia, acute respiratory distress, and other severe and serious complications.
However, the intensity of symptoms in birds vary greatly depending on the strain of the virus, and the type of bird. Bird flu infection with avian influenza A viruses (for example, H5 and H7 strains) can cause widespread disease and deaths among some species of wild and especially domesticated birds such as chickens and turkeys.
The correct solution lies in preventive and curative vaccination to control the spread of the virus. The process of culling is usually done to control the bird flu infection when detected in animals. Apart from culling, safe disposal of all culled animals and animal products is also important.
The authorities concerned also need to strictly enforce decontamination of infected premises, and assure the quarantine of contaminated personnel, and vehicles. It is advised to eat properly-cooked eggs or chicken. As part of precautionary measures, animals culled to control the spread of the virus should not be allowed to enter the food and feed chain.
People who work at the poultry industry are strictly advised to practice hand hygiene, and wear PPEs (personal protective equipment). Moreover, antiviral drugs are considered for consumption to ease bird flu symptoms.