Congenital trichinellosis in the rat.

57 female rats were divided into four groups according to age and gestation. Trichinella spiralis infection was induced by feeding the rats with rat muscle containing about 10000 larvae per gram. The mating and sacrificing of females were done differently for each group. New-born rats were examined by direct trichinoscopy and by peptic digestion of muscle. We found that larvae of T. spiralis which entered the uterus of the pregnant females can pass to the foetus. It was impossible to specify the time when larvae crossed the placenta, but this crossing is made only by those larvae which did not settle and encyst in the striated muscles. The mobilisation of the encysted larvae from skeletal muscles was not demonstrated.