Mechanical transmission of Toxoplasma gondii oocysts by dogs.

Two experiments were conducted to determine if dogs could mechanically transmit Toxoplasma gondii after ingesting cat feces or by rolling in cat feces containing oocysts. In the first experiment, two dogs were fed sporulated T. gondii oocysts; viable sporulated oocysts were present in dog feces for up to 2 days postinoculation (PI). Both dogs seroconverted to T. gondii but did not develop clinical signs of toxoplasmosis. In the second experiment, nonsporulated oocysts were placed on dog skin and fur, and fur clippings were bioassayed for T. gondii in mice. Oocysts did not sporulate on dog fur. The results of this study support the hypothesis that dogs may be involved in the mechanical transmission of T. gondii to humans.