By contact with infected animals or indirectly with secretion or excretion of infected animals, and fomites. Like most viral diseases, the virus is in the blood and secretions before clinical signs appear. Therefore, infected anim als are spreading the virus before anyone knows they are ill. Bad news for stockyards and slaughterhouses. If animals recover, they are solidly immune.
Morbidity is usually low, however, mortality is high.
Sheep associated MCF occurs sporadically on a worldwide basis. In Africa, the wildebeest is the reservoir. Elsewhere, sheep are thought to be the reservoir. Close contact is regarded as essential for transmission via nasal discharge. Wildebeest and sheep have naturally occurring, inapparent infections.