Morbillivirus is a genus of RNA viruses in the Paramyxoviridae family of the order Mononegavirales. The genus contains five
established members: measles, canine distemper, rinderpest, pest des petits-ruminants, and phocine (seal) distemper.
Morbillivirus is one of several viruses that have resulted in previously unrecognized or new diseases.
Measles virus, until recently the only morbillivirus known to affect humans, causes an illness characterized by fever, cough, runny nose, inflamed conjunctivae, and a rash. Before regular vaccination measles was an epidemic disease with biennial cycles in urban areas. Today outbreaks are uncommon except in communities where a substantial number of individuals have not received the primary and booster measles immunizations.
Other than measles, morbilliviruses have affected only animals. However, in late 1994 there was a limited
outbreak of a previously undescribed morbillivirus in horse stables in Brisbane, Australia. Two humans and 21 horses were infected, and one human and 14 horses died. The original source of the infection was not determined. While it has been known that close contact between humans and animals can occasionally lead to cross-species infections, the transmission of a morbillivirus across order, from horse to human, was never before reported until the Australian outbreak.