Effects of the anthelmintics clorsulon, rafoxanide, mebendazole and arprinocid on Echinostoma caproni in ICR mice [corrected and reapublished in J Helminthol 1996 Mar;70(1):95-6]

Female ICR mice, 5 to 6 weeks old, were exposed by stomach tube to 25 metacercarial cysts of Echinostoma caproni per mouse. At 14 days post-exposure, mice were fed by stomach tube clorsulon (1000 mg/kg, 500 mg/kg and 100 mg/kg) or rafoxanide (50 mg/kg, 25 mg/kg and 5 mg/kg) dissolved in dimethylsulphoxide (DMSO) carrier and mebendazole (1000 mg/kg and 500 mg/kg) or arprinocid (100 mg/kg and 50 mg/kg) suspended in a 2:1 polyethylene glycol (PEG)/DMSO carrier. All drugs were obtained from Merck Inc. (Rahway, New Jersey, USA) and only single dose regimes were used. Experimentally infected mice that served as controls received either DMSO or 2:1 PEG/DMSO carriers or were not given the carrier. Mice were necropsied 15v, 16, 18 and 20 days postexposure to worms. Doses of 100 mg/kg of clorsulon and 50 mg/kg of rafoxanide were 100% effective in eliminating the echinostomes on day 1 post-administration of the anthelmintics. Mebendazole and arprinocid were ineffective in eliminating worms at 1 or 2 days post drug administration.

A comparison of Echinostoma trivolvis and E. caproni using random amplified polymorphic DNA analysis

The random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) technique was applied to two closely-related echinostome species, Echinostoma trivolvis and E. caproni, demonstrate interspecific polymorphisms of genomic DNA. Band patterns generated using five individual primers showed that these two echinostomes were genetically distinct, although they share genomic DNA to some extent.

Cytochemical localization of cytochrome c oxidase activity in mitochondria in the tegument and tegumental and parenchymal cells of the trematodes Echinostoma trivolvis, Zygocotyle lunata, Schistosoma mansoni, Fasciola gigantica and Paragonimus ohirai

Cytochrome c oxidase in the mitochondria of the tegument and tegumental and parenchymal cells was examined cytochemically in Echinostoma trivolvis, Zygocotyle lunata, Schistosoma mansoni, Fasciola gigantica and Paragonimus ohirai, trematodes that inhabit different sites in their vertebrate hosts. Clear differences in enzyme activity occurred in the mitochondria of these species, probably reflecting the different energy metabolisms of these worms. Marked aerobic metabolism occurred in S. mansoni and P. ohirai adults that inhabit the host mesenteric veins and the lungs, respectively. The tegument and parenchymal cells of S. mansoni possess relatively few, small mitochondria with tabular cristae which are heavily reactive for cytochrome c oxidase. In P. ohirai, the activity for cytochrome c oxidase in tegumental mitochondria increased gradually from juveniles to adults, reflecting that the respiratory activity increased with growth and the aerobic metabolism is activated when the worms reach the lung. P. ohirai juveniles and adults had two types of mitochondria with different shapes and enzyme activities that were located in two different types of parenchymal cells. The intestinal species, E. trivolvis had mitochondria in the basal aspect of the tegument, and some variations in enzyme activity of their mitochondria in the tegumental and parenchymal cells were observed, suggesting that they possess both aerobic and anaerobic metabolic systems. Z. lunata that live in rodent caeca are devoid of mitochondria in the tegument and have many characteristic mitochondria with undeveloped cristae in the parenchymal cells. Mitochondria of F. gigantica showed weak or no activity for cytochrome c oxidase, suggesting that the worm is well-adapted to an anaerobic environment in the host bile duct.

Effects of Echinostoma caproni infection on the neutral lipid content of the intestinal mucosa of ICR mice

Thin-layer chromatography was used to examine the effects of adult Echinostoma caproni infection on the intestinal mucosa of ICR mice. At 2 weeks postinfection the mucosa of infected mice showed a marked elevation of the free fatty acid fraction compared to that of the uninfected controls. The most abundant neutral lipid fraction of the adult worms was free sterol.

Effects of diet on the lipid composition of the digestive gland-gonad complex of Biomphalaria glabrata (Gastropoda) infected with larval Echinostoma caproni (Trematoda)

This study examined the effects of a larval Echinostoma caproni infection on the neutral lipid composition of the digestive gland-gonad complex (DGG) of Biomphalaria glabrata snails fed hen's egg yolk supplemented with lettuce (Y-L) or lettuce supplemented with Tetramin (L-T). Snails were experimentally infected with the miracidial stage of this echinostome, and their DGGs containing daughter rediae were analyzed for neutral lipids five weeks post-infection by qualitative and quantitative thin-layer chromatography. Light microscopy using Oil Red O (ORO) staining and transmission electron microscopy (TEM) were used to localize neutral lipids in the rediae. The DGGs of infected snails maintained on the Y-L diet showed a significant increase in free sterols and a significant decrease in triacylglycerols compared to uninfected snails maintained on the Y-L diet. The DGGs of infected snails maintained on the L-T diet showed no significant difference in free sterols or triacylglycerols compared to uninfected snails maintained on the L-T diet. ORO staining and TEM showed the presence of lipid droplets in rediae from snails on the Y-L diet. The significant decrease in triacylglycerols in the DGGs of infected snails maintained on the Y-L diet suggests that triacylglycerols were utilized by the rediae.

Argentophilic structures of the miracidium of Echinostoma trivolvis (Cort, 1914) (Trematoda: Echinostomatidae)

Argentophilic structures of the miracidium of Echinostoma trivolvis were described from 80 specimens reared from material originally collected in eastern Pennsylvania, U.S.A. Miracidia were impregnated with 0.5% aqueous silver nitrate solution. The miracidium has 18 epidermal plates arranged in 4 rows of 6 + 6 + 4 + 2 = 18. Up to 20 papillalike structures on the terebratorium were arranged along 3 axes and in 5 groups. A single papilla was located at the base of each of the 6 epidermal plates of the first row. The eyespots were located posterior to the first row of plates and 2 excretory pores were located anterior to the last row of plates.

Experimental infection of juvenile Biomphalaria glabrata with cercariae of Echinostoma trivolvis

Infectivity studies were done on laboratory-reared Biomphalaria glabrata juvenile (neonatal) snails exposed to cercariae of Echinostoma trivolvis. Of the 40 snails, 0.7-1.0 mm in shell diameter, which were exposed to a total of 1,000 cercariae for 24 hr, all were infected with 1-29 viable encysted metacercariae per snail. Biomphalaria glabrata, 1-2 mm in shell diameter, were used to determine the effects of an infectious dose of 25 cercariae/juvenile on subsequent snail survival. The median survival time of 24 exposed snails occurred between day 3 and 4 postinfection, at which time more than 90% of 24 control (unexposed) snails were alive. The high mortality in the E. trivolvis-infected B. glabrata juveniles was probably related to cercarial penetration and encystment in the snail tissue, although histological examination of snails after exposure would be required to determine the actual cause of the observed mortality.

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.

Thin-layer chromatographic and histochemical analyses of neutral lipids in the intramolluscan stages of Leucochloridium variae (Digenea, Leucochloridiidae) and the snail host, Succinea ovalis

Thin-layer chromatographic and histochemical analyses were used to analyze neutral lipids in the intramolluscan larval stages of Leucochloridium variae and in tissues of the snail host Succinea ovalis. Thin-layer chromatography showed that the major neutral lipids in uninfected snails were triacylglycerols and free sterols. The major neutral lipids in brood sacs minus their encysted metacercariae and in sporocysts were triacylglycerols and free sterols. Encysted metacercariae showed a significant free fatty acid fraction in addition to triacylglycerols and free sterols. Residual snail tissue (mainly head, foot, and visceral mass) from infected snails from which parasites were removed showed only a free sterol fraction. Histochemical staining of tissues with oil red O (ORO) showed the presence of neutral lipid droplets in the brood sac and sporocyst walls and mainly in the suckers, parenchyma, and excretory system of the encysted metacercariae. The residual snail tissue was ORO negative.

The effect of dexamethasone on the course of Echinostoma caproni and E. trivolvis infections in the golden hamster (Mesocricetus auratus)

Golden hamsters (Mesocricetus auratus) were given intramuscular injections of dexamethasone and infected with Echinostoma caproni or E. trivolvis. All animals were necropsied on day 14 postinfection. Dexamethasone treatment at high doses resulted in increased parasite recovery. Decreased total white blood cell counts and decreased relative splenic weights were observed in corticosteroid-treated hamsters. Dexamethasone-treated animals also demonstrated significantly lower mean parasite dry weights for E. caproni. Specific serum IgG against the parasites was not detected in corticosteroid-treated hamsters on day 14 postinfection.

An enzyme-linked immunosorbent assay for detecting anti-Echinostoma trivolvis (trematoda) IgG in experimentally infected ICR mice. Cross-reactivity with E. caproni

An enzyme-linked immunosorbent assay (ELISA) utilizing surface glycocalyx-membrane crude antigen of adult Echinostoma trivolvis was developed for the detection of circulating anti-E. trivolvis IgG in experimentally infected ICR mice. An antigen concentration of 10.0 micrograms/ml was used, and it was possible to detect anti-E. trivolvis IgG at a dilution of 1/3,200. On day 10 postinfection (p.i.), all infected mice had anti-E. trivolvis IgG reactive with the surface glycocalyx antigen. The IgG level varied over a 40-day period, showing a time-dependent pattern with a peak on day 16 p.i. The results concerning reciprocal cross-reactivity indicate that adult E. trivolvis and E. caproni share at least some of the surface antigens and express species-specific antigenic determinants in ICR mice at similar, nonsignificantly (P = 0.76) different levels.

Light and scanning electron microscopy of Echinostoma caproni (Trematoda) during maturation in ICR mice

Light (LM) and scanning electron microscopy (SEM) were used to study the maturation of Echinostoma caproni in 13 ICR mice, each of which was exposed to 50 encysted metacercariae and necropsied at 1-20 weeks postinfection (p.i.). All 13 mice were infected with 20-30 worms/host and half the worms were used for LM and the remainder, for SEM. Body area measurements showed that the worms grew rapidly from day zero (excysted metacercariae) to 4 weeks p.i. and less rapidly thereafter. Area measurements of organs showed that the growth of the acetabular area paralleled that of the body. Gonadal area growth was less rapid than acetabular growth, and the area of the posterior testis was always greater than that of the anterior testis. The most remarkable change in topography occurred by 5 weeks p.i. when some of the ventral tegumentary spines became multipointed with 2-5 points/spine. Spine division was associated with a decline in worm growth, but the significance of this finding is unclear. Spine division probably facilitates the feeding, abrasion, and migration of this echinostome in the mouse small intestine.

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.

ELISA method for detecting anti-Echinostoma caproni (Trematoda: Echinostomatidae) immunoglobulins in experimentally infected ICR mice

An enzyme-linked immunosorbent assay (ELISA) utilizing surface glycocalyx membrane crude antigen of adult Echinostoma caproni was developed for the detection of circulating anti-E. caproni immunoglobulins in sera from experimentally infected ICR mice. Whole blood, serum, and dried blood on filter paper gave similar results. The latter was selected for convenience. A concentration of 10.0 micrograms/ml of antigen was optimal in terms of specificity, sensitivity, and test speed. It was possible to detect anti-E. caproni immunoglobulins at a dilution of 10(-4.11). Low absorbance values (< 0.050) of nonspecific background were observed. In a blind trial the described ELISA accurately differentiated sera taken from infected and uninfected mice. All experimentally infected mice had ELISA-detectable anti-E. caproni immunoglobulins reactive on day 8 postinfection (PI) with the surface glycocalyx antigen. The antibody level varied widely over a 40-day period showing a characteristic and consistent pattern. Mice developed antibodies to E. caproni rapidly, with antibody levels rising by day 8 PI and peaking 6-10 days later. Experimentally infected mice showed time-dependent changes in antibody levels. The proposed ELISA is fast, easy to perform, reproducible, and requires a minimal amount of equipment to collect blood samples. The assay can be used for the detection of anti-E. caproni immunoglobulins in experimentally infected mice, along with monitoring antibody levels in selected groups of mice or for surveys of laboratory experiments where evidence of infection is required.

Infectivity, growth, distribution and acetabular attachment of a one-hundred metacercarial cyst inoculum of Echinostoma trivolvis in ICR mice

Female ICR mice, 6-8 weeks old, were exposed to 100 metacercarial cysts/host of Echinostoma trivolvis to determine the effects of this cyst dosage on worm infectivity, distribution, growth and acetabular attachment in the host small intestine. Of 42 exposed mice, 22 were infected 4 to 17 days postinfection (PI) with a mean worm recovery of 11 to 41%. Mean body area of worms increased from about 0.4 mm2 on day 4 PI to about 2.0 mm2 by day 9 PI. No consistent pattern of worm growth was seen beyond day 9. Distribution data showed that worms were found mainly in the anterior part of the small intestines on day 4 PI and then more posteriorly up to day 8 PI. Worm distribution patterns were quite variable beyond day 11 PI. Scanning electron microscopy showed that the acetabulum left a distinct 'fingerprint' or acetabular plug on the intestinal mucosa of the host. The 'fingerprint' was temporary and disappeared within 1 min after worms were removed from the intestines.

High performance thin-layer chromatographic analysis of sugars in Biomphalaria glabrata (Gastropoda) infected with Echinostoma caproni (Trematoda)

High performance thin-layer chromatographic analysis was done on the hemolymph and digestive gland-gonad complex (DGG) of Biomphalaria glabrata snails experimentally infected with the intramolluscan stages of Echinostoma caproni. The major sugars detected in both the DGG and hemolymph of infected and uninfected snails were glucose and trehalose. Quantitative analysis by scanning densitometry showed a significant reduction in glucose in both the hemolymph and DGG of infected snails at 4, 6, and 8 wk postinfection. A similar analysis on trehalose showed that this sugar was significantly reduced at 6 wk postinfection in the hemolymph and DGG of infected snails and could not be detected from these sites in infected snails by 8 wk postinfection. Findings from this study were compared with information on sugars in B. glabrata infected with larval stages of Schistosoma mansoni.

Light and scanning electron microscopic observations of the eggs, daughter rediae, cercariae, and encysted metacercariae of Echinostoma trivolvis and E. caproni

Light microscopy (LM) and scanning electron microscopy (SEM) were used to determine interspecific differences between various larval stages of 2 allopatric species of 37-collar-spined echinostomes, Echinostoma caproni and E. trivolvis. The abopercular and embryo diameters of the eggs of E. trivolvis were significantly different from those of E. caproni. The abopercular knobs of E. caproni and E. trivolvis have shallow and deep infoldings in the eggshells, respectively. Interspecific differences were noted in the tegument, tegumentary papillae, and spherical bodies around the mouth and in the papilliform process of the two rediae. The cercaria of E. caproni has one ventral tail fin-fold, whereas that of E. trivolvis has two; both species have two dorsal tail fin-folds. The outer metacercarial cyst diameter of E. caproni was significantly greater than that of E. trivolvis. E. caproni has a smoother outer cyst wall than does E. trivolvis.

The expulsion of Echinostoma trivolvis (Trematoda) from ICR mice: extension/retraction mechanisms and ultrastructure of the collar spines

Ultrastructural observations of collar spines and surrounding tissues associated with extension/retraction mechanisms of the spines were made on Echinostoma trivolvis recovered from ICR mice or golden hamsters. The spine consisted mainly of a homogeneous, crystalline structure of moderate to heavy electron density. The spine was surrounded by an outer layer of tegument-like material. Interstitial material was located between this outer layer and the surrounding tegument. Muscle bundles associated with spine movements were anchored by hemidesmosomes to interstitial material. Contraction of these muscles caused an invagination of the tegument surrounding a spine, resulting in spinal protrusion. Relaxation of these muscles resulted in spinal retraction. An immunocytochemistry technique using colloidal gold confirmed the presence of actin in the collar spines. Most of the collar spines of excysted metacercariae and juveniles maintained in a defined medium supplemented with fresh hamster serum were extended, whereas worms maintained in mouse serum mainly showed retracted spines. Apparently, factors in mouse serum are involved in spinal retraction.

Echinostoma caproni and E. trivolvis alter the binding of glycoconjugates in the intestinal mucosa of C3H mice as determined by lectin histochemistry

Mouse (C3H) mucosal glycoconjugates were examined in normal small intestines and intestines infected with Echinostoma caproni or E. trivolvis using six different fluorescein-conjugated lectins: Triticum vulgaris agglutinin (WGA), Ulex europaeus agglutinin I (UEA-I), Ricinus communis agglutinin I (RCA-I), Glycine max soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), and Arachis hypogaea peanut agglutinin (PNA). The expression of lectin-binding sites and the intensity of the binding of lectins in the mouse small intestines were changed by infection with the echinostomes. Specific differences in the reaction to glycoproteins were clearly observed between the mouse intestines infected with E. caproni and those infected with E. trivolvis. In E. caproni infection, binding of most of the lectins to the villi was remarkably reduced in accord with the villous atrophy and loss of goblet cells. In contrast, in E. trivolvis infection, the binding of WGA, RCA-I and DBA was reduced in the microvillar surfaces, but binding of UEA-I and SBA were unchanged compared to the control intestines. The lectin binding to goblet cells in E. trivolvis-infected mice mostly increased. These observations may reflect the marked increase in goblet cells and the less severe damage in the villi of E. trivolvis infection compared to E. caproni infection. Most of the glycoconjugates were slightly reduced in the hyperplastic crypts except for N-acetyl glucosamine. It is possible that glucose metabolism in the host intestines infected with E. trivolvis was activated, resulting in an increase in the rate of mucin synthesis as well as qualitative changes in mucus, thereby mediating the expulsion of the worms.