Avian Influenza

Avian flu, bird flu or avian influenza is a disease that occurs in birds, mainly gallinaceous birds. The incubation period is three days to two weeks. The disease is fatal to chickens, turkeys, waterfowl, raptors and cranes. The risk of people in Europe becoming infected with bird flu is very small.

The causative agent of the disease is a variant of the influenza virus: the influenza A virus. This virus is highly variable, so that new variants are created every time. Viruses multiply in a host cell. In one in 10,000 cases, small mistakes in the multiplication process (mutations) can create a virus that is different, and possibly more dangerous, than the original virus. This process of mutation in viruses is called antigenic drift. Influenza A viruses also involve reassortment in which different viruses exchange genetic material with each other, called antigenic shift. A low pathogenic avian influenza virus can mutate into a highly pathogenic virus which is a highly contagious, lethal variant for most bird species.

Symptoms of the influenza virus in birds

Infections with the influenza virus range from mild to fatal, depending on the pathogenic capacity of the virus concerned. The symptoms indicate flu-like symptoms with drowsiness, watery eyes and swollen throats. The comb of the bird also discolours. Some birds die immediately after the first infestation. The classic bird flu virus is well known to everyone who has experienced the bird flu crisis of 2003 and in 2016.

Virus variants Influenza

Influenza virus H5N1

H5N1 is a variant of the avian flu virus that is dangerous for humans. The virus is contagious and deadly to birds, but can also infect humans, for whom it is not yet very dangerous. "H5" refers to the type of hemagglutinin in the protein coat and "N1" to the type of neuraminidase. In both cases these are antigens that play a role in respectively binding to the cell membrane and the release of newly produced viruses from an infected cell.

H5N1 is endemic to birds in South and East Asia and is in danger of becoming endemic in all birds. This is because infected migratory birds spread the virus worldwide. It is known that poultry is susceptible to the virus and that it can be infected by, among other things, the faeces of infected migratory birds.

Influenza virus H5N8

H5N8 is a variant of the bird flu virus that is dangerous for humans. The virus is contagious and deadly to birds, but can also infect humans, for whom it is not yet very dangerous. "H5" refers to the type of hemagglutinin in the protein coat and "N8" to the type of neuraminidase. In both cases these are antigens that play a role in respectively binding to the cell membrane and the release of newly produced viruses from an infected cell.

H5N8 is endemic to birds in South and East Asia and is in danger of becoming endemic in all birds. This is because infected migratory birds spread the virus worldwide. It is known that poultry is susceptible to the virus and that it can be infected by, among other things, the faeces of infected migratory birds.

The Influenza virus and the environment

The influenza virus can survive indefinitely in an environment of several tens of degrees below zero. However, it cannot withstand heat.

Survival Times:

  • more than 30 days at 0 °C or lower (frost);
  • 6 days at 37°C - human body temperature, high fever can destroy the virus;
  • 3 hours at 56°C;
  • 30 minutes at 60°C or higher.

The disinfection of equipment, surfaces and the like with heat must therefore take place for more than 30 minutes at temperatures above 60 °C.

Various oxidizing and disinfecting agents are also known that can render the virus inactive as well as an acidic environment.

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Thousands of exotic birds destroyed at avian dealer in Bocholt (B)

The highly pathogenic bird flu virus type H5 was diagnosed on Friday at a avian dealer in Bocholt (B). To prevent further spread of the virus, about 6,000 exotic birds, will be destroyed.

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