[Experimental data on the infestation of the young of 5 species of Lymnaea by Fasciola hepatica L].

The ability of five lymnaeid species (Lymnaea glabra, L. palustris, L. peregra, L. stagnalis, L. truncatula) to act as intermediate hosts of Fasciola hepatica was investigated under controlled conditions. Each snail born in the laboratory (at 23 degrees C) was infected when 1-24-hours-old, using 3 miracidia of F. hepatica. The percentage of infected snails ranged from 15.8% to 64.5% on day 30 post-exposure. The shell height of snails with evolutive infection was significantly reduced than the shell height of snails with abortive infection or controls. The mean number of cercariae produced by the snails with evolutive infection was low: from 12.2 to 18.4 cercariae per snail. The length of the shedding period was one day for 114 snails, two days for 41 snails and 3-31 days for the 54 other snails. We did not observe a distinct rythm in cercarial production of these snails. All infections of guinea-pigs with these metacercariae were positive. The significance of these observations is discussed.