Phocine distemper virus
|''Phocine distemper virus|
| Immunohistochemical staining of the lung of a seal with PDV.|
Immunohistochemical staining of the lung of a seal with PDV.
Phocine distemper virus (PDV) is a paramyxovirus of the genus morbillivirus that is pathogenic for pinniped species, particularly seals. Clinical signs include laboured breathing, fever and nervous symptoms.
In the same year, two more outbreaks of viral disease in aquatic mammals were observed. Another Morbillivirus caused the deaths of Baikal seals (Phoca sibirica) in Lake Baikal, Siberia. This was later identified as a strain of the closely related canine distemper virus (CDV) and was probably transmitted to the seals from terrestrial animals, CDV being widespread in canines in the Lake Baikal region.
In 2002, an epidemic of PDV along the North Sea coast resulted in the deaths of 21,700 seals, estimated to be 51% of the population.
The suddenness of the emergence of PDV and related viruses in aquatic mammals has implicated environmental changes as the cause. Pollutants have been posited as contributors by interfering with the ability of animals to mount a defense against infection. Alternatively, climate change and overfishing may have forced aquatic species that naturally harbour the viruses into new areas, exposing immunologically naïve populations.