Understanding The Avian Bird Flu Virus And A Look Into Its History2 Νοεμβρίου, 2022
Avian bird flu, a viral disease, also termed as bird flu, avian influenza, type A flu or genus. This flu is a kind of influenza hosted by birds but can affect other animals and particularly humans also. The virus in general is the influenza virus ‘A’ but is a bit different every time the flu breaks out, because of the evolutionary changes it keeps undergoing. New viruses keep getting formed because of genetic mutation and are named using a H number and an N number, which denote different pathogenic profiles. Some of those ones which for sure affect human populace and did so in the past are, H1N1 (Spanish flu, 1918-19) H2N2 (Asian flu, 1957-58), H3N2 (Hong Kong flu, 1968-69), etc. Some of those identified are extinct now because of the constant mutations taking place in the structure of the virus which self destructs its capabilities to infect humans anymore. Also new viruses have come up and currently the major pandemic (epidemic over a wide geographical area) threat is from H5N1 virus.
It was first discovered in Italy in 1878 and was even called fowl plague because of the enormity of its effect in chicken livestock. It was however only in 1955 when avian flu was confirmed to be caused by influenza A viruses. Wild fowl is the natural carrier of the virus, though it is not affected by the virus and is only a transmitter to birds, pigs, horses, etc. The bodies (intestines to be more specific) of gulls, waterfowls and shorebirds are said to be “natural reservoirs” of the disease. Their bodies have long adapted to the problem and have developed internal antibodies to combat the virus. The adaptation, however, does not extend to other species. Hence domestic birds are the most affected and other animals and humans are only marginally affected, in numbers. The bird flu virus causes two forms of influenzas, namely, a low pathogenic form which shows only nominal symptoms and a high pathogenic form which affects internal organs and might prove 100% fatal in 48 hours.
The disease is contagious and spreads through air and in manure. The transmission occurs from air, contaminated water, equipments especially those used in animal farms, clothing, etc. At high temperatures the virus gets destroyed, like in prolonged summers, cooking, steaming, fires, etc. but survives for long periods in cold weather. The bird flu virus starts showing its effects in 3 to 5 days, and can be fatal if highly pathogenic. Hundreds and millions of birds get killed every year, since the most commonly practiced way of eliminating the virus is to slaughter the infected animals.
It has a long history of affecting human population in epidemic form. Those subtypes which infect humans are called human influenza virus. The only known ones are H1N1, H1N2 and H3N2, with H5N1 having a potential threat. The symptoms shown in humans are same as those from other influenza, namely, fever, cough, muscle fatigue, conjunctivitis and sometimes breathing problems and fatal pneumonia. Detection of the avian bird flu virus in the human body can be done using general influenza virus tests, but this might be unreliable. The most reliable test till date is microneutralization but is a complicated test and can be performed only in highly professional laboratories. Normal antiviral drugs work against the human influenza virus but other specific drugs for specific new viruses are being developed.
As far as humans are concerned, the bird flu virus has substantial risk of an influenza epidemic in near future. A primary concern is the rapid spreading of the virus (infecting domesticated birds) between continents with migrating birds. Short term strategies are to kill the animals, vaccinating poultry, stop human travelling to and from the affected region, whereas a long term solution would be vaccination and hygienic lifestyles.