Bird flu (Aviaire Influenza) is caused by influenza virusses. A virus is an organism that requires a host (an animal or human, for example) in order to survive. It uses functions of the host to reproduce, among other things. In the case of bird flu, the virus can spread from one human to another by means of contaminated (dead) poultry or in a contaminated environment (such as a bird market).
The virus is particularly a threat to birds. An outbreak of bird flu A(H5N8) occurred in the Netherlands in November 2016. So far, concerning this variety, there have been no cases of illness among humans. Fatal cases have occurred in the past due to other varieties of the virus, A(H5N1), A(H7N7) and A(H7N9).

Companies where bird flu prevails are obligated to report this to the national hotline animal disease. The company will then be cleared and the poultry in the surrounding area will be examined as well. This in order to halt the spreading of the virus as quickly as possible.