Differential alterations in the small intestine epithelial cell turnover during acute and chronic infection with Echinostoma caproni (Trematoda).

BACKGROUND: The intestinal epithelium plays a multifactorial role in mucosal defense. In this sense, augmented epithelial cell turnover appears as a potential effector mechanism for the rejection of intestinal-dwelling helminths. METHODS: A BrdU pulse-chase experiment was conducted to investigate the infection-induced alterations on epithelial cell kinetics in hosts of high (mouse) and low (rat) compatibility with the intestinal trematode Echinostoma caproni. RESULTS: High levels of crypt-cell proliferation and tissue hyperplasia were observed in the ileum of infected mice, coinciding with the establishment of chronic infections. In contrast, the cell migration rate was about two times higher in the ileum of infected rats compared with controls, with no changes in tissue structure, indicating that an accelerated cell turnover is associated with worm expulsion. CONCLUSION: Our results indicate that E. caproni infection induces a rapid renewal of the intestinal epithelium in the low compatible host that may impair the establishment of proper, stable host-parasite interactions, facilitating worm clearance.

Moderate Echinostoma trivolvis infection has no effects on physiology and fitness-related traits of larval pickerel frogs (Rana palustris).

High intensity infections of Echinostoma trivolvis metacercariae decrease survival and growth of young amphibian larvae. However, in nature, parasites are highly aggregated, which results in a large proportion of the amphibian population being only moderately infected. Survival and growth responses at these more-common, low-infection levels remain poorly studied. Thus, we investigated the effects of moderate Echinostoma trivolvis metacercariae infection (following exposure to 0, 10, 30, or 90 cercariae) on the growth and development of pickerel frog (Rana palustris) tadpoles. We measured metabolism to determine whether increased energy expenditure is a potential physiological mechanism underlying previously documented reduced growth. Furthermore, we quantified tadpole intestine size, which can exhibit plasticity in response to changing metabolic demands, and we characterized metacercariae distribution in tadpole kidneys. Metacercariae encysted in the pronephros significantly more than in the mesonephros, but tended to occur equally in right and left kidneys. Two mo post-infection (PI), there were no changes in tadpole survival, development, intestine size, or growth related to metacercariae infection. Similarly, metacercariae did not significantly increase metabolic rates during encystment or at 1 mo PI. Our study demonstrated that modest E. trivolvis infections, representative of a large proportion of the host population, had no detectable effects on fitness-related traits in laboratory isolation from other ecological variables.

Mating behaviour of Echinostoma caproni and E. trivolvis in concurrent infections in hamsters.

Young adults of Echinostoma caproni and E. trivolvis were recovered from hamsters. Some worms of each species were exposed to [3H]tyrosine for 1 h to label sperm, and these were transplanted singly to uninfected hamsters with various combinations of unexposed worms of either the opposite species or both species. Worms recovered 5 days later were serially sectioned, processed for autoradiography and observed for the location of radioactive sperm. Interspecies mating was detected when E. caproni was the sperm donor and E. trivolvis the recipient, but not the converse. The cross-insemination rate during interspecies mating was very low (13%) when compared to the normal rate of E. caproni intraspecies mating (52%). When single donor adults of either E. caproni or E. trivolvis had a choice of both recipient species, no interspecies mating took place, but both self- and cross-inseminated in a non-restrictive mating pattern typical of echinostome species. After transplantation, both species localized in their normal habitat within the hamster intestine. However, 25% of opposite species recoveries were found within 1 cm of each other, making interspecies mating a possibility.

Infectivity and growth of Echinostoma revolutum (Froelich, 1802) in the domestic chick.

Infectivity and growth studies in domestic chicks were carried out on a strain of Echinostoma revolutum isolated from Lymnaea elodes snails in Indiana, U.S.A. Of 21 chicks, each fed 40 +/- 10 cysts of Echinostoma revolutum, 16 (64%) were infected with a total of 269 (32%) worms from approximately 840 cysts. Worms were found only in the ceca and rectum at 2-14 days p.i. In vivo excysted metacercariae were obtained in the lower ileum and ceca at 4 h p.i. Excysted metacercariae averaged 0.2 mm in length and 0.02 mm2 in body area. Worm length averaged 1.3 mm on day 6, 2.3 mm on day 8 and 3.6 mm on day 14. Mean body area averaged 0.29 mm2 on day 6, 0.62 mm2 on day 8 and 1.93 mm2 on day 14. Worms first became ovigerous on day 12. Growth of E. revolutum in the chick was delayed compared to previous findings on E. trivolvis, a closely related species of 37-collar-spined echinostome in the E. revolutum complex.

The effects of the presence and absence of intestinal contents on survival, size and distribution of Echinostoma caproni in ICR mice.

Fifteen female ICR mice, 6-8 weeks old, were each exposed to 25 metacercarial cysts of Echinostoma caproni. To determine the effects of withholding food on survival, size and distribution of E. caproni in ICR mice, two groups of five each were maintained without food for 1 day (group A) or 2 days (group B) prior to necropsy. Group C consisted of five mice maintained with food for the duration of the experiment. All mice were necropsied at 12 days postinfection. There was no significant difference in worm survival, body area or distribution between group A and C or group B and C mice. The results of this experiment show that short-duration removal of food has no effect on worm survival, size or distribution of E. caproni adults in the small intestine of the ICR mouse.

Infectivity, growth, distribution and fecundity of a six versus twenty-five metacercarial cyst inoculum of Echinostoma caproni in ICR mice.

Female ICR mice, 6-8 weeks old, were exposed to 6 (group A) or 25 (group B) metacercarial cysts/host of Echinostoma caproni to determine the effects of these cyst dosages on infectivity, growth, distribution and fecundity of worms in the small intestines. All 30 mice exposed (15 in group A and 15 in group B) were infected and there was no significant difference in the percentage of worm recovery between group A and B at 2, 4 and 8 weeks postinfection (PI). Growth was rapid in both groups with worm body areas increasing from about 3mm2 at 2 weeks PI to about 7 mm2 at 8 weeks PI. More worms from group B were in the anterior sections of the small intestines at 2 and 4 weeks PI than those from group A. However, at 8 weeks PI more worms from Group A were in the anterior sections of the small intestines than those from group B. There were marked differences in our findings on infectivity, growth and distribution of E. caproni in ICR mice using 6 and 25 cyst inocula compared to a previous study using the same echinostome and cyst inocula in NMRI mice, presumably related to the mouse strain. Fecundity studies were somewhat comparable in both studies showing an approximate three to four times increase in the average number of eggs/gram of faeces in mice receiving 25 versus 6 cyst inocula.

Negative effect on early post-implantation pregnancy and progesterone levels in mice infected with the intestinal trematode Echinostoma caproni.

Infection in mice (BALB/cABom) with the intestinal trematode Echinostoma caproni had a negative influence on pregnancy. The effect of the infection set in immediately following implantation (day 5 of pregnancy) resulting in fewer foetuses being present in infected mice on day 9 than in the controls. Ovulation, fertilization of eggs, and implantation itself were obviously not impaired. The infected mice had significantly lower serum progesterone levels on day 5 of pregnancy than the non-infected controls. It is speculated that the progesterone levels in the infected female mice were too low to secure early post-implantation gestation.

[The effect of different concentrations of surface-active substances on the size of the circadian rations and on the duration of food passage in Lymnaea stagnalis infected with Echinostoma revolutum parthenitae]. / Vliianie razlichnykh kontsentratsii poverkhnostno-aktivnykh veshchestv na velichinu sutochnykh ratsionov i prodolzhitel'nost' prokhozhdeniia pishchi u Lymnaea stagnalis, invazirovannogo partenitami Echinostoma revolutum.

In solutions of the detergent "Kristall" (0.9 and 90 mg.l.-1) there were established statistically reliable differences in the values of day rations and duration of food passing both in infected and free from infection molluscs. In noninfected individuals day rations increase 1.5 to 5 times and the duration of food passing 5 to 7 times. In infected animals the value of day rations decrease and the duration of food passing increases less intensively.

Dynamics of the leukocytic response of Biomphalaria glabrata during the larval development of Schistosoma mansoni and Echinostoma liei.

The daily evolution of the number of hemocytes in Biomphalaria glabrata was ascertained under three conditions: uninfected snails, snails infected with Schistosoma mansoni, and snails infected with Echinostoma liei. The Results show differences between the three experiments as well as in the average hemocyte density over the whole experimental period, as in the temporal dynamics of circulating hemocyte number. Specifically, it appears that the development of E. liei in B. glabrata induces a density of circulating hemocytes greater than that in uninfected B. glabrata or in snails infected with S. mansoni. The hemocyte dynamics observed in both experimental groups might best be interpreted by taking into account differences in the immunogenic stimulating capacity of the two trematodes and different physiological functions of the hemocytes brought into play during the infection: wound repair, nutrient digestion and transport, and excretion.