Thijs
Kuiken,† Seamus Kennedy,* Paul D. Jepson,‡
Robert Deaville,‡ Morag Forsyth,# Tom Barrett,#
Marco W.G van de Bildt,† Albert D.M.E. Osterhaus,†
Tariel Eybatov,§ Callan Duck$$, Aidyn Kydyrmanov,**
Igor Mitrofanov,†† Susan Wilson ## Thijs
Kuiken,† Seamus Kennedy,* Paul D. Jepson,‡
Robert Deaville,‡ Morag Forsyth,# Tom Barrett,#
Marco W.G van de Bildt,† Albert D.M.E. Osterhaus,†
Tariel Eybatov,§ Callan Duck$$, Aidyn Kydyrmanov,**
Igor Mitrofanov,†† Susan Wilson ##
†Seal Rehabilitation and Research Center, Pieterburen, The
Netherlands
*Department of Agriculture and Rural Development, Belfast, Northern
Ireland, UK
‡Institute of Zoology, Regents Park, London, UK
#Institute of Animal Health, Pirbright, Surrey, UK
§Geological Institute of the Azerbaijan Republic Academy of
Sciences, Baku, Azerbaijan
$$Sea Mammal Research Unit, University of St. Andrews, Fife, UK
**Laboratory of Virus Ecology, Institute of Microbiology and Virology, Almaty,
Kazakhstan
††Akademgorodok, Institute of Zoology, Almaty, Kazakhstan
## Caspian Environment Programme Ecotoxicology Project, Portaferry, Northern
Ireland, UK
Unexplained
high mortality of Caspian seals (Phoca caspica) occurred before and during spring
migration in 2000. To determine the cause, we examined 18 seals found dead between
May and August 2000 along the north and central coasts of the Caspian Sea. Analyses
included gross and microscopic pathology, isolation procedures for viral and
bacterial infections, immunohistochemistry and RT-PCR for morbillivirus, serology,
and measurement of levels of algal toxins, trace metals, and organochlorines.
The primary diagnosis in 9 of 11 juveniles and 2 of 7 adults was canine distemper.
Grossly, these seals had multifocal pulmonary consolidation. Histologic lesions
included a necrotizing broncho-interstitial pneumonia and lymphocytic depletion
of lymphoid organs. The epithelium of multiple tissues had characteristic intracytoplasmic
inclusion bodies, which were positive for morbilliviral antigen by immunohistochemistry.
By phylogenetic analysis, the isolated canine distemper virus was identical
to that found in a Caspian seal in 1997. Three of four adult seals without canine
distemper had IgG antibodies to canine distemper virus. In contrast to the virgin
soil epidemics of canine distemper in Baikal seals (Phoca siberica) in 1987-88
and of phocine distemper in harbour seals (Phoca vitulina) and grey seals (Halichoerus
grypus) in 1988, the above data suggest that canine distemper is endemic in
the Caspian seal population and may cause recurrent peaks in mortality.
