Detection of Toxoplasma gondii in wild bivalves from the Kerguelen and Galapagos archipelagos: influence of proximity to cat populations, exposure to marine currents and kelp density

Mosquera, Juan D; Escotte-Binet, Sandie; Poulle, Marie-Lazarine; Betoulle, Stéphane; St-Pierre, Yves ORCID: https://orcid.org/0000-0002-1948-2041; Caza, France; Saucède, Thomas; Zapata, Sonia; Bayas, Rosa De Los Angeles; Ramirez-Villacis, Dario X; Villena, Isabelle et Bigot-Clivot, Aurélie (2024). Detection of Toxoplasma gondii in wild bivalves from the Kerguelen and Galapagos archipelagos: influence of proximity to cat populations, exposure to marine currents and kelp density International Journal for Parasitology , vol. 54 , nº 12. pp. 607-615. DOI: 10.1016/j.ijpara.2024.06.001.

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Résumé

Oocysts of the protozoan Toxoplasma gondii are found in felid feces and can be washed into coastal waters, where they persist for months, attaching to algae and accumulating in invertebrates. We used wild bivalves to assess contamination of coastal waters of the Kerguelen and Galapagos archipelagos by this zoonotic parasite. Additionally, we leveraged the contrasting situations of these archipelagos to identify some potential drivers of contamination. In the Galapagos, with a cat density reaching 142 per km2, 15.38% of the sampled oysters (Saccostrea palmula) tested positive for T. gondii by quantitative real-time PCR (qPCR) (n = 260), and positive samples were found in all eight sampling sites. In Kerguelen, with 1-3 cats per km(2), 40.83% of 120 tested mussels (Mytilus edulis platensis) were positive, and positive samples were found in four out of the five sampling sites. These findings provide evidence of T. gondii contamination in the coastal waters of these archipelagos. Furthermore, T. gondii-positive bivalves were found on islands located 20 km away (Galapagos) and 5 km away (Kerguelen) from the nearest cat population, indicating that T. gondii oocysts can disperse through waterborne mechanisms over several kilometers from their initial deposition site. In the Galapagos, where runoff is infrequent and all sites are exposed to currents, the prevalence of qPCR-positive bivalves did not show significant variations between sites (p = 0.107). In Kerguelen where runoff is frequent and site exposure variable, the prevalence varied significantly (p < 0.001). The detection of T. gondii in Kerguelen mussels was significantly correlated with the site exposure to currents (odds ratio (OR) 60.2, p < 0.001) and the on-site density of giant kelp forests (OR 2.624, p < 0.001). This suggests that bivalves can be contaminated not only by oocysts transported by currents but also by consuming marine aggregates containing oocysts that tend to form in kelp forests.

Type de document:	Article
Mots-clés libres:	Oysters; Mussels; Oocysts; Protozoan; Mytilus edulis platensis; Saccostrea palmula; qPCR
Centre:	Centre INRS-Institut Armand Frappier
Date de dépôt:	05 nov. 2024 22:03
Dernière modification:	05 nov. 2024 22:03
URI:	https://espace.inrs.ca/id/eprint/16104

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