Natural infections of three freshwater snails with Fasciola hepatica and/or Paramphistomum daubneyi were studied during two periods in 1996 and 1997 (June–July and September–October) on 18 farms located in the departments of Vienne and Haute Vienne (central France), and known for low prevalences of F. hepatica infections in ruminants. A total of 1573 Lymnaea glabra and 1421 L. truncatula 6 mm high or more were collected in the meadows of 13 farms and dissected under laboratory conditions. Snails with single or concurrent infections of F. hepatica and/or P. daubneyi were found for each Lymnaea species. InL. truncatula, global prevalences of natural infections with F. hepatica (3.8% in June–July, and 3.6% in September–October) were significantly greater than those recorded for P. daubneyi (1.1% and 0.8%, respectively). In L. glabra, global prevalences of F. hepatica infections (0.4% in each investigation period) were significantly lower than those found in L. truncatula, whereas there were no significant differences between prevalences of P. daubneyi infections. A total of 2721 Planorbis leucostoma measuring at least 4 mm in diameter were collected in the meadows of the other five farms on which L. truncatula was absent. In these planorbids, global prevalences of natural infections with F. hepatica were 0.4% in each period of investigation. Contrary to fasciolosis, snail infections with P. daubneyi were not noted on all farms of the Vienne and Haute-Vienne departments. Natural single or concurrent infections with F. hepatica and/or P. daubneyi in L. glabra and a natural infection of P. leucostoma with F. hepatica were found in swampy meadows on acid soil.
(Accepted November 24 1999)