[An outbreak of distemper among seals (I)].

The cause of a recent outbreak of a serious disease of seals in the North and Baltic Seas, in which so far, over 9000 of the population of 16,000 animals have died, was investigated. Three viruses have been considered as the possible causative agents: a herpesvirus, a picornavirus and canine distemper virus. It was concluded mainly on the basis of serological data that canine distemper virus was the primary cause of the outbreak. The role of other factors on the extent and the severity of the outbreak needs to be investigated.