Direct evidence of an extra-intestinal cycle of in tigers () by isolation of viable strains.

Toxoplasmosis is one of the most common zoonotic diseases in the world. Felines excrete environmentally resistant oocysts. However, there is no direct evidence to prove tigers are the intermediate host of . Here, we show that, IgG antibodies to in 80% (8/10) of captive tigers. Two viable strains (ToxoDB genotype #9) were isolated by bioassay in mice using striated muscles of two tigers (Tiger#3 and Tiger#8). Additionally, mice were confirmed as -positive by bioassay of feces #89-110, but no viable strain was isolated successfully. The fecal samples from tigers may contain oocysts. This is the first report of isolation from tigers. These results provide direct evidence that an extra-intestinal cycle of may develop in tigers.