Retrospective of the 1988 European seal epizootic

Abstract

The diseases that killed >18 000 harbour seals Phoca vitulina and a small number of grey seals Halichoerus grypus in the North Sea, the Kattegat-Skagerrak and the S Baltic in 1988 has now been well described. A newly recognised virus, phocine distemper virus (PDV), of the genus Morbillivirus, was the primary cause of the disease. The high mortality can probably be explained by the fact that a highly pathogenic virus was introduced into a naive population with no specific immunity to the infectious agent. Factors such as organochlorine pollution or crowding of seals at haul-out sites may have exacerbated the impact of the disease in some areas. Harp seals Phoca groenlandica are frequently infected by PDV and they have recently invaded the North Sea whre they have been observed in the vicinity of harbour seal haul-out sites. Migrating harp seals are a plausible vector of the virus. PDV has been transmitted to terrestrial carnivores causing distemper outbreaks in Danish farmed mink Mustela vison in 1989, and an epizootiological link cannot be excluded. -from Authors