Peste des petite ruminants (pest of small ruminants) is caused by a virus whose antigen is closely related to that of the rinderpest virus. It is characterized by symptoms similar to those of rinderpest with erosion of the oral mucous layer as well as pulmonary lesions. It is found in Africa from the Sahara to the Equator as well as in the Arabian peninsula. In its epizootic form, it causes-heavy mortalities and in its enzootic form, leads to a pneumopathic bacterial condition. Prophylaxis can be either through the use of a heterologous vaccine against rinderpest or a recently developed homologous vaccine.