Toxoplasma gondii infection in stranded St. Lawrence Estuary beluga Delphinapterus leucas in Quebec, Canada

The St. Lawrence Estuary (SLE) beluga Delphinapterus leucas in Quebec, Canada, is endangered due to intensive hunting in the 19th and 20th centuries and subsequent anthropogenic contamination and human activities in the region. Infectious disease is a primary cause of death in this population. The protozoan parasite Toxoplasma gondii is reported in numerous marine mammal species, including beluga. In the present study, 55 tissue samples (heart and brain) collected from 34 stranded SLE beluga were analysed by PCR followed by DNA sequencing and restriction fragment length polymorphism analysis (RFLP) to determine the PCR prevalence and genotypes of T. gondii in these beluga. Of 34 beluga tested, 44% were positive for T. gondii by PCR, with males having a higher prevalence of infection than females and with more infected neonates and juveniles than adults. Molecular analyses indicated that all T. gondii infecting stranded SLE beluga grouped into genotype II, which predominates in humans. While our results indicate that a high prevalence of stranded beluga are PCR-positive for T. gondii infection, very few deaths are attributed to toxoplasmosis based on published necropsy results. Toxoplasma gondii can cause a range of diseases, including neurological deficits, and more data are needed to investigate this parasite's effect on population recovery.