Submitted to: Epidemiology and Infection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/1999
Publication Date: N/A
Citation: Interpretive Summary: Infection with the single celled parasite Toxoplasma gondii is widely prevalent in livestock and humans. It causes abortion in livestock and mental retardation and loss of vision in children. Humans become infected by eating uncooked meat infected with Toxoplasma cysts or food and water contaminated with oocysts (resistant stage) excreted only by the cat. Scientists at the Beltsville Agriculture Research Center and the Universit of Saskatchewan, Canada investigated the epidemiology of the first water-borne outbreak of toxoplasmosis in humans in Victoria, British Columbia. They found evidence that the municipal water supply was contaminated with oocysts excreted by domestic cats and cougars. These findings will be of interest to public health workers, veterinarians, physicians and parasitologists.
Technical Abstract: The world's first documented toxoplasmosis outbreak associated with a municipal water supply was recognized in 1995 in Victoria, British Columbia, Canada. It was hypothesized that domestic cat (Felis catus) or cougar (Felis concolor) faeces contaminated a surface water reservoir with Toxoplasma gondii oocysts. An extensive investigation of the Victoria watershed 1 year following the outbreak documented the presence of an endemic T. gondii cycle involving the animals inhabiting the area. Cats and cougars were observed throughout the watershed. Serological evidence of T. gondii infection was demonstrated among domestic cats living in the Victoria area. Cougars were found to shed T. gondii oocysts. Serological evidence of T. gondii infection in deer mice living in the riparian environments of the watershed suggested that T. gondii oocysts were being shed near the water edge. Contamination of Victoria's water supply with T. gondii oocysts potentially occured during the study period and future waterborne toxoplasmosis outbreaks in this and other communities are possible.