Seroprevalence of Toxoplasma gondii in North-eastern Atlantic harbor seal (Phoca vitulina vitulina) and grey seal (Halichoerus grypus)

Antibodies to Toxoplasma gondii were determined in serum samples from 47 grey seals (Halichoerus grypus) and 56 harbor seals (Phoca vitulina vitulina) from the Atlantic coasts of United Kingdom and France. Antibodies to T. gondii assayed by the modified agglutination test (MAT) were found in 14 (13.6%; IC95%: 7.0–20.2) of 103 seals tested, with titres of 1:25 in 13 seals and 1:50 in 1 seal. Seroprevalence against T. gondii (MAT 1:25 or higher) was significantly higher in grey seals (23.4%) compared to harbor seals (5.4%). No significant differences were found between seroprevalence against T. gondii and sex, age or geographical locations. These results show natural exposure of European harbor and grey seals to T. gondii oocysts in the Atlantic Ocean. To the best of our knowledge, this is the first serological survey of T. gondii in European grey and harbor seals.