Myxomatosis is a disease caused by Myxoma virus, a poxvirus in the genus Leporipoxvirus. The natural hosts are tapeti (Sylvilagus brasiliensis) in South and Central America, and brush rabbits (Sylvilagus bachmani) in North America. The myxoma virus causes only a mild disease in these species, but causes a severe and usually fatal disease in European rabbits (Oryctolagus cuniculus). Myxomatosis is an excellent example of what occurs when a virus jumps from a species adapted to it to a naive host, and has been extensively studied for this reason. The virus was intentionally introduced in Australia, France, and Chile in the 1950s to control wild European rabbit populations.