Comparative Parasitology 67(2) 2000 - Peru State College

238 COMPARATIVE PARASITOLOGY, 67(2), JULY 2000
500
0.01
8 10
Day post-infection
Figure 1. Goblet cell (mean ± SE)/VCU (•) and mast cell (•) (mean ± SE)/VCU numbers of the
anterior section of the ileum of jirds, each of which was infected with Echinostoma trivolvis metacercarial
cysts. A logarithmic transformation was performed on the number of the cells for normalizing the data.
For comparison of the cell counts, goblet cell numbers were multiplied 10 times as for the mast cells.
study, the worms moved posteriad to the cecum
and colon plus rectum by day 12 p.i. In BALE/
c mice infected with E. trivolvis, the recovery
rate of the worms was over 44% for days 6-10
p.i. and worm expulsion occurred from day 10
to 12 p.i., corresponding to the peak increase in
goblet cells (Fujino et al., 1996). Those worm
recovery rates were much higher than what is
seen in the present study on jirds, i.e., 35.4%
and 33.9% at days 5 and 8 p.i., respectively.
Therefore, worm expulsion occurred from days
8 to 12 p.i. These data showed that worm expulsion
in jirds occurred earlier than in murine
hosts, probably reflecting a difference in the
peak number of goblet cells in jirds and mice.
Christensen et al. (1990) examined the establishment,
survival, and fecundity in E. caproni and
the allopatric species of E. trivolvis in hamsters
and jirds. They noted that the jird exhibited an
overall low susceptibility to E. caproni infection.
The jird's low susceptibility to E. caproni
is different from that of E. trivolvis. According
to Ellerman and Morrison-Scott (1951), the jird
Copyright © 2011, The Helminthological Society of Washington
(M. unguiculatus) belongs to the subfamily Gerbillinae
of the family Muridae and differs both
taxonomically and genetically from the golden
hamster (M. auratus) of the subfamily Cricetinae
and also from various mouse strains of Mus
musculus of the subfamily Murinae. It is known
that Gerbillinae is genetically closer to Murinae
than Cricetinae (Ellerman and Morrison-Scott,
1951). The present infection data on E. trivolvis
in jirds generally correspond to the above-noted
taxonomic and genetic differences in murine
hosts. In conclusion, the recoveries of E. trivolvis
from jirds were lower than those from mice
and much lower than those from golden hamsters.
It is possible that these differences in recoveries
reflect the genetic differences among
these 3 hosts, jirds, mice, and hamsters.
Kinetic changes in the number of goblet cells/
VCU at the anterior sections (n = 50) of the
ileum with or without the parasites present are
shown in Figure 1. The number of goblet cells
in infected jirds increased markedly, peaked at
24.3 ± 0.6/VCU at day 10 p.i. and then de-
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