Another phocine distemper outbreak in Europe.

The seal population of Northern Europe was able to recover from the 1988 phocine distemper epidemic that killed about 18,000 seals. However, starting at the beginning of May 2002, unusually high mortality among harbor seals (Phoca vitulina) was noted on the shores of Anholt, an island off the east coast of Denmark. Since then, 182 of about 900 animals, both adult and juvenile, died with clinical signs of respiratory and nervous disease. About 440 seals have been found dead on the east coast of Denmark, and the disease also appears to have spread to Sweden, where 100 seals were reported dead along the west coast (1). Most recently, over 10 seals were found moribund or dead along the coast of the Netherlands in the second half of June. The clinical signs observed were reminiscent of those in seals that died in 1988 of infection with a morbillivirus (2), subsequently identified as PDV, a new member of the genus (3). We performed necropsies on seven seals (four adults, one subadult, and two juveniles) in variable states of decomposition found at Anholt or on the nearby Danish mainland and on one freshly dead juvenile seal from Vlieland, an island off the Dutch coast. Tissue samples (lung, kidney, bladder, and brain) were examined for morbillivirus nucleic acid by reverse-transcriptase polymerase chain reaction (RT-PCR), with a set of universal morbillivirus primers, P1 (5 -ATGTTTATGATCACAGCGGT-3 ) and P2 (5 -ATTGGGTTGCACCACTTGTC-3 ), that are based on conserved sequences in the phosphoprotein (P) gene. Tissue samples from three Danish seals (two adults and one juvenile) and the Dutch seal were positive, giving the expected products of 429 base pairs (bp). Selected fragments of the PCR products were sequenced for phylogenetic analysis. The resulting sequences closely matched ( 97% homology) those of PDV isolates from harbor seals in 1988 and were distinct from those of canine distemper virus (CDV) and other members of the genus Morbillivirus (Fig. 1). Except for one nucleotide change in the P gene fragment, the sequences obtained from Denmark and the Netherlands were identical, indicating that seals from widely separated regions of Northern Europe were infected by the same virus. Serum samples were tested for morbillivirus-specific immunoglobulin M (IgM) antibody by antibody-capture enzymelinked immunosorbent assay (ELISA), with goat antibody to dog IgM–coated plates and peroxidase-labeled CDV antigen for detection. The goat antibody to dog IgM preparation specifically captures seal IgM, as was shown in routine serological tests for CDV infection. Two adult Danish seals and the Dutch seal had IgM antibodies, showing re-