Epidemic encephalomyelitis
Avian encephalomyelitis is a viral disease of the central nervous system of chickens, pheasants, turkeys, and quail. It has a worldwide distribution. Morbidity 5-60% depending on the immune status of the majority of parents, mortality high. Vertical transmission is very important, transmission occurs over about 1-2 weeks, some lateral. The route of infection is transovarian with an incubation period of 1-7 days; lateral transmission is probably by the oral route, incubation >10 days. Virus in faeces may survive 4 weeks or more.