P. Hourdin et al., THE DEVELOPMENT OF FASCIOLA-HEPATICA PARTHENITAE IN LYMNAEA-TRUNCATULA BY MODIFICATION OF MUELLERIUS-CAPILLARIS INFECTION, International journal for parasitology, 23(2), 1993, pp. 235-243
Adult and juvenile Lymnaea truncatula (height 4 and 1 mm, respectively
) were subjected to a dual infection with either Fasciola hepatica and
Muellerius capillaris, or with M. capillaris and F. hepatica at 4-h,
7-, 14- and 30-day intervals between the two exposures. The results we
re compared with those of snails which had been infected with a single
parasite species. In dually infected snails, there was a high mortali
ty at the second exposure to both parasite species, and it was strongl
y increased by each reinfection. The interexposure time had a signific
ant influence on these mortality rates. Histological examination demon
strated a decreased number of rediae (50% or greater) in dually infect
ed snails beginning with the 4-h interval in adults and the 7-day inte
rval in juveniles. The exposure order and the time interval between ex
posures had a significant influence on the number of rediae: the numbe
r of parasites per snail decreased as the time interval lengthened. De
layed maturity occurred in live free rediae in snails infected by F. h
epatica and M. capillaris at the 14- and 30-day intervals. In those in
fected by M. capillaris and F. hepatica, time to reach maturity was no
t modified compared to that in snails infected with a single species.
Protostrongylid larvae were clearly less numerous in dually infected a
dult snails than in corresponding mono-infected snails. Third-stage la
rvae were found in the 14- and 30-day groups, regardless of exposure o
rder and were absent in mono-infected snails.