Inhibitory effects of monensin on shedding of Toxoplasma oocysts by cats.

Toxoplasma oocyst shedding by cats was suppressed by 0.02% monensin incorporated in dry cat food. Ten of 12 cats that had not shed oocysts were immune when reinfected with mice chronically infected with Toxoplasma. The medicated food, which was well accepted and tolerated by kittens, could be useful to minimize risks of infection for pregnant women and small children from pet cats defecating in soil close to homes. However, in the presence of stray cats a false sense of security may be engendered.