SCHISTOSOMA-MANSONI OVIPOSITION IN-VITRO REFLECTS WORM FECUNDITY IN-VIVO - INDIVIDUAL-DEPENDENT, PARASITE-AGE-DEPENDENT AND HOST-DEPENDENT VARIATIONS

In an attempt to determine whether in vitro oviposition of adult S. ma nsoni reflects the fecundity status of worms in vivo, Mongolian gerbil s and ICR, BALB/c and SCID mice were infected with about 100 cercariae and examined on an individual basis, 5-12 weeks later, for worm burde n, counts of eggs in liver and small intestine, and for the rate of eg g deposition of ex-vivo female worms cultured in vitro, singly or in p airs, over a 3-5 day incubation period. The percentage of egg-laying f emale worms and the number of eggs laid/female after 3 days in culture showed, like worm fecundity in vivo, wide inter-worm variability, esp ecially in 5-, 6- and 12-week-old worms; varied significantly with the age of the parasite with a maximum level attained by worms of approxi mately 8 weeks of age; and differed in worms recovered from different host species and strains. The data taken together indicate that measur ing the egg-producing ability of S. mansoni in vitro reflects the fecu ndity status of worms in vivo, and additionally provides likely explan ations for hitherto poorly understood findings on schistosome fecundit y. (C) 1997 Australian Society for Parasitology. Published by Elsevier Science Ltd.