Fourteen pregnant rabbits were each infected with 300 cercariae of Schistosoma japonicum and divided into two groups. Group M (n = 8) was infected during mid-gestation (the organogenetic stage) and group L (n = 6) was infected during late-gestation (the post-organogenetic stage). Mother rabbits and rabbit kittens were killed 45–60 days after infection and perfused in order to obtain worm counts. Furthermore, faecal egg counts and tissue egg counts from livers were obtained from the mother rabbits as well as the rabbit kittens. All mother rabbits became infected harbouring 207.6 ± 20.2 and 220.0 ± 27.5 adult worms in group M and L, respectively. In groups M and L, 13.5% and 46.7% of the kittens were infected, respectively. In 12 of 14 litters at least one kitten was infected. The infected kittens harboured between one and three adult S. japonicum. The livers of the kittens infected with a worm pair displaced lesions as a result of egg deposition. The results, therefore, show that congenital transmission of S. japonicumcan occur in rabbits. The close anatomical resemblance between the rabbit and human placenta may be indicative of the presence of congenital transmission of S. japonicum infection in humans.
(Accepted December 22 1999)