Synonyms
Avian influenza; avian influenza Microbiological: H5N1, H7N2, H7N9Avian influenza is an infectious disease caused by certain forms of the influenza virus. In a broader sense, bird flu is also known as “avian influenza” or “avian influenza”. Normally, avian flu mainly affects poultry (especially chickens, turkeys and ducks), but extensive mutations of the causative viruses can also infect humans.
This disease is a rapidly spreading, potentially life-threatening infection. Especially the virus subtypes H7N9, H5N1 and H7N2 have made headlines in recent years. The respective names of the virus subtypes are based on specific surface structures (proteins).
These surface structures include above all the enzymes haemagglutinase (H) and neuraminidase (N). These specific proteins enable the virus to infect and damage the host organism. In the meantime, about 16 different haemagglutinases and 9 different neuraminidases are known. The composition of the respective enzyme subtypes on the virus envelope is decisive for the name of the virus. In general, a distinction is made between highly pathogenic (causing severe diseases) and low pathogenic (only provoking mild symptoms) avian influenza and its viral agents.
Causes
Bird flu, like all other types of flu, is an infectious disease caused by viruses. Contrary to the original assumption that bird flu only affects poultry, a transmission potential to mammals has now been proven for some subtypes. The underlying virus is mainly found in the respiratory tract secretions and faeces of infected animals.
After excretion, the avian flu virus remains infectious for more than 100 days in liquid manure. In faeces and poultry meat and in eggs stored at four degrees Celsius, the avian flu virus can survive for about 30 to 35 days. At a room temperature of about 20 degrees Celsius, the survival time of the viral pathogens is reduced to about 20 days.
At temperatures above 22 degrees Celsius, however, the stability of the viral envelope is reduced. The viruses responsible for the development of avian influenza therefore die out quickly. At temperatures of 55 to 60 degrees Celsius, the avian flu viruses are killed within a very short time.
Transmission to mammals (especially to humans) takes place mainly via the respiratory tract. The inhalation of virus-containing dust particles is already sufficient to trigger the disease. Furthermore, contact with infected animals is considered highly risky if hand hygiene is inadequate. In addition to the transmission of bird flu from animals to humans, a direct human-to-human infection is now also assumed. However, this theory has not yet been reliably confirmed.
