The in vivo development of Schistosoma bovis in the Nile rat

The in vivo development of the Sudanese strain of Schistosoma bovis in the Nile rat, Arvicanthus niloticus is described. Six stages in development are distinguished: the 'lung form' (stage 1), attaining maximum numbers on day 5 post-infection; the 'closed-gut form' (stage 2) on day 14, characterized by the union of the gut caeca behind the ventral sucker; 'organogeny' (stage 3) on day 17, the male possessing one testis and a gynaecophoric canal and the female a narrow uterus; 'gametogeny' (stage 4) on day 26, with pairing, the male having four fully developed testes and the female an ovary; 'egg-shell formation' (stage 5) on day 35; 'oviposition' (stage 6) on day 37, with the female showing uterine eggs. The time to complete in vivo development in the Sudanese strain of S. bovis is more rapid than in the Israeli strain, 37 and 42 days respectively.