Abstract
Toxoplasma gondii infection has been reported in numerous species of marine mammals, some of them with fatal consequences. A serosurvey for T. gondii infection was conducted in pinnipeds from an oceanographic park in Portugal (n = 60); stranded pinnipeds on the Portuguese coast (n = 10); and pinnipeds captured in Lorenzensplate, Germany (n = 99). Sera from 169 pinnipeds were tested for the presence of antibodies to T. gondii by the modified agglutination test with a cut-off titre of 25. An overall seroprevalence of 8.9% (95% confidence interval: 5.1–14.2) was observed. Antibody titres of 25, 50, 100, 1600 and ≥3200 were found in five (33.3%), two (13.3%), five (33.3%), one (6.7%) and two (13.3%) animals, respectively. Pinnipeds under human care had a seroprevalence of 20.0% (12/60), in contrast to 2.8% (3/109) in wild pinnipeds (p < 0.001). General results suggest a low exposure of wild pinnipeds to T. gondii, while the seroprevalence found in pinnipeds under human care highlights the importance of carrying out further studies. This is the first serological survey of T. gondii in pinnipeds in Portugal and the first infection report in South African fur seal (Arctocephalus pusillus pusillus).
Highlights
Toxoplasmosis is a worldwide zoonosis caused by the obligate intracellular parasite Toxoplasma gondii, which affects a wide range of homeothermic animals, including marine mammals
The prevalence of antibodies to T. gondii detected in pinnipeds under human care was higher (20.0%) and significantly different from the one obtained in wild pinnipeds (2.8%), which may be explained by several factors, including the increased potential sources of infection in pinnipeds under human care
Despite the low seroprevalence obtained in the present study, the results indicate natural exposure to T. gondii in wild pinnipeds
Summary
Toxoplasmosis is a worldwide zoonosis caused by the obligate intracellular parasite Toxoplasma gondii, which affects a wide range of homeothermic animals, including marine mammals. T. gondii transmission to marine mammals remains unknown [1]. The presence of felids, the definitive hosts, in nearshore environments can result in contamination of coastal habitats, because they are the only hosts that can excrete through their faeces, the environmentally resistant stages, the oocyst of T. gondii. The ingestion of sporulated oocysts in marine environment, either directly or indirectly, is considered the main source of infection, in addition to ingestion of oocysts directly from marine waters or consumption of paratenic hosts (such as molluscs) that have concentrated the oocysts [3]. While T. gondii does not multiply in poikilothermic animals, bivalve molluscs, sardines and anchovies can assimilate and concentrate oocysts [4,5,6,7]
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