Diurnal migration of Echinostoma caproni (Digenea: Echinostomatidae) in ICR mice

Twenty-four female ICR mice, 12 acclimated to a 12 ∶ 12 light-dark cycle and 12 to a 12 ∶ 12 dark-light cycle for 7 days, were each infected with 10 metacercariae of Echinostoma caproni. Infected mice were maintained on their respective lighting regimes for 28 days. Six mice (3 from each group) were necropsied at 4-hr intervals beginning at 0700 hr. The small intestine was removed, opened, and the position of individual worms and worm clusters was measured to the nearest 0.1 cm. Each intestine was subsequently divided into 20 equal segments and individual worms and worm clusters were assigned to the appropriate segment based on the original measurements. All worms were found in the posterior 55% of the intestine (ileum). All posterior segments (10-20), with the exception of segment 18, harbored at least 1 worm at some time. A Monte Carlo simulation of worm abundance in segments 10-17 over all time periods indicated a random distribution, while the same analysis of segments 10-20 indicated a non-random distribution due to large numbers of worms in segment 20 and to the absence of worms in segment 18. To analyze temporal changes in worm distribution, mice were grouped by time of necropsy as follows: night (1900 and 2300 hr), morning (0300 and 0700 hr), and day (1100 and 1500 hr). During the night and morning, E. caproni was heavily concentrated in segments 10-17 and, during the day, worms were located more posteriorly, with a heavy concentration in the last segment (20).     

Reproduction of the trematode Echinostoma caproni parthenites (Digenea: Echinostomatidae)

Dynamics of the reproduction in the trematode Echinostoma caproni parthenites (Echinostomatidae) was observed. Early laying and maturation of the generative cells are for the first time shown to be characteristic for all parthenogenetic generations. Really the process of reproduction had been finishing to the beginning of the generating of new age by parthenites. Mother sporocysts, as well as redia of different generations, in fact stop producing new generative cells with the beginning of the generating of new age, and assume the function of a brood pouch. This feature was considered previously as peculiar mainly to mother sporocysts. Data on the autotomy of the anterior body end in mother sporocysts are verified. In our opinion, these data are an evidence of an early manifestation of the evolutionary trend to the morpho-functional regress and disintegration of the parasitic stage of mother sporocyst.     

Development of the partenitae infrapopulation of Echinostoma caproni (Digenea: Echinostomatidae)

The first generation of Echinostoma caproni partenitae is represented maternal sporocysts developing in the cardium of the Biomphalaria mollusk. During all their life, they produce rediae of maternal generation. Rediae of Echinostoma caproni of all generations are similar. The first generation consists of maternal rediae forming only redoid embryos. Due to this process, the number of partenitae increases very fast. The next generations are represented by daughter rediae. In the beginning of their life they produce redoid embryos but later begin forming cercariae. The number of rediae produced before this shift of production depends on the population density. Further, the partenitae retain their potential ability to form rediae but realize it in exceptional cases. Generative organs of all generations are germinal masses. Proliferation of generative elements and beginning stages of redia and cercaria development take place within these masses. The infrapopulation of E. caproni belongs to the "prolonged type", because it is a complete microhemipopulations; its existence is limited by a lifespan of the mollusk host.     

Concurrent infections of Echinostoma caproni and Echinostoma trivolvis in ICR mice.

ICR female mice, 6- to 8-weeks old, were exposed concurrently to 25 metacercarial cysts of Echinostoma caproni and 25 metacercarial cysts of Echinostoma trivolvis and necropsied 10 and 14 days post-infection. Controls consisted of mice exposed singly to either 25 or 50 E. caproni or E. trivolvis cysts. All 23 mice exposed to E. caproni cysts were infected with a total of 331 worms (37.8%), whereas only 11 (37.9%) of 29 mice exposed to E. trivolvis cysts were infected with a total of 77 (6.4%) worms. In the concurrent infections, 13 (59.1%) of 22 mice were infected with both species and the percentage of worm recovery was 72.6% for E. caproni and 14.2% for E. trivolvis. There was no difference in worm distribution of either species in single vs concurrent infections. In concurrent infections at 14 days PI, there was a significant decrease in the body area of worms of both species, when compared to single worm species.     

Development of mother sporocysts of Echinostoma caproni (Trematoda: Echinostomatidae)

New data on the migration and development of Echinostoma caproni mother sporocysts in two mollusk species of the genus Biomphalaria are obtained. It is confirmed, that the formation of primary and second generative cells takes place only as a result of undifferentiated cells' proliferation and following differentiation of some of them. These processes in miracidium, as well as in the parasitic stage of mother sporocyst, take place in a special organ, germinal mass, which occupies caudal position in both cases. The supposition of the role of germinal mass as the universal centre of multiplication and development of generative elements in all generations of Echinostoma caproni parthenites is confirmed. It is established, that mother sporocysts do not relize their reproductive potential completely, and the degree of its realization depends on the conditions arising in the host organism.     

Complete Mitochondrial Genome of Echinostoma hortense (Digenea: Echinostomatidae)

Echinostoma hortense (Digenea: Echinostomatidae) is one of the intestinal flukes with medical importance in humans. However, the mitochondrial (mt) genome of this fluke has not been known yet. The present study has determined the complete mt genome sequences of E. hortense and assessed the phylogenetic relationships with other digenean species for which the complete mt genome sequences are available in GenBank using concatenated amino acid sequences inferred from 12 protein-coding genes. The mt genome of E. hortense contained 12 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and 1 non-coding region. The length of the mt genome of E. hortense was 14,994 bp, which was somewhat smaller than those of other trematode species. Phylogenetic analyses based on concatenated nucleotide sequence datasets for all 12 protein-coding genes using maximum parsimony (MP) method showed that E. hortense and Hypoderaeum conoideum gathered together, and they were closer to each other than to Fasciolidae and other echinostomatid trematodes. The availability of the complete mt genome sequences of E. hortense provides important genetic markers for diagnostics, population genetics, and evolutionary studies of digeneans.     

A comparison of Echinostoma caproni and Echinostoma trivolvis (Trematoda: Echinostomatidae) adults using isoelectrofocusing.

An isoenzymatic analysis using thin-layer agarose gel isoelectrofocusing on laboratory strains of Echinostoma trivolvis and Echinostoma caproni adults showed characteristic monomorphic phenotypes for phosphoglucomutase and glucose phosphate isomerase. The fixed allelic variation observed between these 2 taxa is consistent with their current classification as distinct species.     

The effects of crowding on adults of Echinostoma revolutum (Digenea: Echinostomatidae) in experimentally infected golden hamsters, Mesocricetus auratus

All 30 female golden hamsters, Mesocricetus auratus, fed either 125 +/- 50 (group A), 300 +/- 50 (group B), or 500 +/- 50 (group C) metacercarial cysts of Echinostoma revolutum were infected 7-35 days postexposure. The mean number of worms in A, B, and C were 62, 96, and 212, respectively. Most of the worms in A were in the jejunum, but in C worms were about equally distributed in the duodenum, jejunum, and ileum, and some were in the cecum. The body area and wet and dry weights of worms from C were significantly less than that of A or B at 2, 4, and 5 wk postinfection. Echinostoma revolutum eggs were in the feces of 100% of the hamsters by days 12, 13, and 14 in A, B, and C, respectively.     

Kinetics of antibodies and antigens in serum of mice experimentally infected with Echinostoma caproni (Trematoda: Echinostomatidae)

The present study reports on the kinetics of antibodies and antigens in serum of mice experimentally infected with 75 metacercariae of Echinostoma caproni during the first 12 wk postinfection (wpi). Antibody titers in the serum of mice were determined by an indirect enzyme-linked immunosorbent assay (ELISA) using excretory/secretory (ES) antigens of E. caproni. The early detection of antibodies against ES antigens of E. caproni is feasible using indirect ELISA. Mice developed significant antibody responses at 2 wpi, and the values progressively increased until the end of the experiment. This may be related to the intestinal absorption of adult worm antigens that induces humoral responses. The presence of E. caproni circulating antigens was determined by a capture ELISA based on polyclonal rabbit antibodies against ES antigens of E. caproni. High levels of seroantigens in mice were detected by 1-2 wpi, probably because of the local inflammatory responses in mice induced by the adult worms. A drop in circulating antigen levels was observed at 9 wpi, which could reflect changes in the intestinal tissues over the course of the infection.     

Single- and five-worm infections of Echinostoma caproni (Trematoda) in the ICR mouse

Twenty-nine (64%) of 44 ICR mice fed a single metacercarial cyst of Echinostoma caproni and all of 23 mice each fed five cysts were infected with ovigerous worms at necropsy 2-4 weeks post-infection. Each host fed five cysts had two to five worms at necropsy, and all worms were either paired or clustered. Distribution of worms in the small intestine was similar in single- and five-worm infections and all worms were located 17-20 cm anterior to the ileo-cecal valve. Both single and multiple worms produced eggs with fully-developed miracidia. The number of eggs per uterus in 2-week-old multiple worms was almost twice that of single worms. The body area of 3- and 4-week-old multiple worms was significantly greater than that of single worms of the same age.     

The expulsion of Echinostoma trivolvis and retention of Echinostoma caproni in the ICR mouse: pathological effects

The infectivity and distribution of Echinostoma trivolvis were studied in female ICR mice each infected with 25 metacercarial cysts. At 7 and 10 days post-exposure worm recoveries were 58.8 and 58.4%, respectively. Worm recovery declined to 38.2% by day 14, to 6.4% by day 21, and 0% by day 28. The distribution of the parasites demonstrated an anteriad shift over time. Comparative histopathological studies were carried out on E. trivolvis and Echinostoma caproni in the mouse. Compared to control and E. trivolvis-infected intestine, mouse intestine infected with E. caproni showed marked dilation and villous atrophy. E. trivolvis-infected intestine showed a nearly two-fold increase in goblet cells compared to control intestine, whereas the intestine of E. caproni-infected mice showed almost complete goblet cell loss. Additionally, there was a marked increase in collagen in the intestinal musculature of the mice infected with E. trivolvis compared to control and E. caproni-infected mice.     

Preliminary data on the chromosomes of Echinostoma caproni Richard, 1964 (Trematoda: Echinostomatidae)

The karyotype of Echinostoma caproni Richard, 1964 is studied. There are eleven pairs of chromosomes (2n=22). Two pairs are submetacentric (Nos. 4 and 5). C-banding methods revealed a large block of heterochromatin in No. 3 and two blocks in No. 5. E. cinetorchis (see Terasaki et al., 1982) and E. barbosai (see Mutafova & Kanev, 1983) also have 22 chromosomes, but the metacentric or submetacentric chromosomes are Nos. 8 and 11 for the former and No. 10 for the latter. ac]19860425     

Echinostoma echinatum (Zeder 1803) sensu Kanev (Digenea: Echinostomatidae): a note of caution

The re-examination of the voucher specimens identified by Kanev et al. (1987) as E. echinatum (Zeder, 1803) showed that two distinct species have been considered as E. echinatum: E. sarcinum Dietz, 1909, possessing 47 collar spines [Lymnaea truncatula strain — set ‘L’ (No. 326 TB)] and Echinostoma sp. (?echinatum) with 37 collar spines [Planorbis planorbis strain — set ‘P’ (No. 327 TB)]. The material of E. sarcinum is described and differentiated from E. revolutum and E. echinatum (sensu Kanev, 1985). The present results suggest that species identity of the material described as E. echinatum in Kanev's (1985) experimental study requires further clarification.     

The role of light and gravity in the experimental transmission of Echinostoma caproni (Digenea: Echinostomatidae) cercariae to the second intermediate host, Biomphalaria glabrata (Gastropoda: Pulmonata)

Trematode cercariae inhabit predictable environments and respond to trigger cues with genetically fixed releaser responses when foraging for the upstream host. The effect of light and gravity on the transmission of Echinostoma caproni cercariae to Biomphalaria glabrata was investigated experimentally. Transmission chambers were constructed of clear polyvinyl chloride pipe. Snails were constrained within the chamber to prevent movement, while permitting the cercariae to swim freely. A trial consisted of 2 infected B. glabrata shedding E. caproni cercariae placed at the center of the chamber, with 5 uninfected B. glabrata placed 10 cm on either side (or above and below) of the shedding snails as sentinels. There was no significant difference in the prevalence of infection sentinel snails in either experiment (light vs. dark or top vs. bottom); however, mean intensity was significantly higher in sentinel snails in the dark portion of the chamber (42.5 vs. 10.4; P = 0.001) and the top of the transmission chamber (66.1 vs. 38.0; P = 0.0003). There was a high correlation between the number of metacercariae collected from sentinel snails and the total number of infective units (metacercariae + unsuccessful cercariae): r = 0.992 (light vs. dark) and r = 0.957 (top vs. bottom), respectively, at cercariae densities estimated from 22 to 3,304/L. The results suggest that cercariae of E. caproni exhibit negative photo- and geotaxis in searching for a second intermediate host. Stereotypical releaser responses to environmental trigger cues (light and gravity) allow E. caproni cercariae to exploit flexible strategies for completing the life cycle consistent with the broad range second intermediate and definitive hosts used by E. caproni cercariae and adults, respectively.     

Effects of Echinostoma caproni infections on metallic ions in the intestinal mucosa of ICR mice

Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used to study metallic ions in the intestinal mucosa of ICR mice infected with Echinostoma caproni and the mucosa of uninfected control mice. Infected mucosa (n = 9 with about 100 mg wet weight per sample) were examined at 2 weeks p.i. in mice that were infected with about 25 worms per host. Uninfected mucosa (n = 9 with about 100 mg wet weight per sample) were examined in the same time frame as the infected mucosa. Five metals were measured in the mucosa by ICP-AES analysis, as follows: calcium, potassium, magnesium, sodium and zinc. There were no significant differences (Student's t-test, P > 0.05) in the concentrations of calcium, potassium or zinc in infected versus uninfected mucosa. The concentration of sodium was significantly greater (P < 0.05) in the mucosa of infected versus uninfected mucosa, but the situation was reversed in regard to magnesium.     

Infectivity, growth, and distribution of Echinostoma caproni (Trematoda) in the ICR mouse

Host-parasite interactions of the intestinal trematode Echinostoma caproni were studied in ICR laboratory mice. All of 40 mice, each fed 25 metacercarial cysts of Echinostoma caproni, were infected 1-20 wk postinfection (PI) with a mean of 17.2 worms/host. At 24 and 29 wk PI only 2 of 6 mice (33%) were infected, with a mean of 4.2 worms/host. Mean body area of worms increased rapidly to about 5 mm2 by week 2, increased less rapidly to 8.8 mm2 by week 12, plateaued until week 24, and then declined. Mean dry weight of worms increased rapidly to about 0.5 mg by week 2, less rapidly to 1.4 mg by week 12, and then plateaued until week 24 PI. From 1 to 8 wk PI most worms localized in the jejunum and ileum; later most worms were in the jejunum and duodenum. Considerable differences were seen in the growth and distribution of E. caproni in the ICR mouse compared with previous studies on this echinostome species in the NMRI mouse.     

Kinetics of Echinostoma caproni (Trematoda: Echinostomatidae) antigens in feces and serum of experimentally infected hamsters and rats

This study reports on the kinetics of antibody production to Echinostoma caproni and the dynamics of antigens in feces and sera in 2 experimental hosts (hamsters and rats) that display different degrees of susceptibility with this echinostome. Echinostoma caproni produced chronic infections in hamsters, whereas rats lost the infection at 49-56 days postinfection (DPI). Hamsters developed higher antibody responses than rats, probably in relation to different intestinal absorptions of worm antigens in each host species. The levels of coproantigens were indicative of the course of infection in each host. Positive coproantigen levels were detected at 1-2 DPI in both hosts, and the values remained positive until the end of the experiment in hamsters; in rats, the coproantigen levels reverted to negative values, coinciding with the loss of infection. High levels of circulating antigens were detected in hamsters from 21 DPI to the end of the study. In contrast, low levels of E. caproni seroantigens were detected in rats only. These observations may reflect the differences in local inflammatory responses induced by E. caproni in each host species.     

Effects of a 100 metacercarial cyst inoculum on the host-parasite relationship of Echinostoma caproni and ICR mice

The host-parasite relationship of a 100 metacercarial cyst inoculum of Echinostoma caproni in the ICR mouse was examined. Three groups of mice, A, B and C, each with six mice per group were used and all mice were necropsied at 14 days postinfection (p.i.), at which time the worms were ovigerous. Group A consisted of uninfected controls, whereas group B received 25 cysts per mouse (low dose) and group C received 100 cysts per mouse (high dose). There was no significant difference in food consumption between any of the groups from 0 to 14 days p.i. Control mice increased their body weight by 12%, group B by 5%, and group C showed a less than 1% increase in body weight between 0 and 14 days p.i. Echinostome parasitism caused a significant increase in the diameter of the mouse gut, with the gut of group C being more significantly dilated than that of either group A or B. The average worm recovery from group B was 20 worms per host, compared to 72 worms per host from group C. The mean wet and dry weights per worm from group B were 2.4 and 0.4 mg, respectively as compared to 0.6 and 0.2 mg respectively for group C. The mean number of uterine eggs per worm from group B was 180 compared to 125 for worms from group C. Worms from group C were more widely distributed in the small intestine than those from group B. Crowding effects associated with the high dose infection were clearly demonstrated in E. caproni from ICR mice.     

Infectivity, growth, and development of Echinostoma revolutum (Digenea: Echinostomatidae) in the golden hamster, Mesocricetus auratus

All 30 female golden hamsters, Mesocricetus auratus, each fed 100 +/- 25 metacercarial cysts of Echinostoma revolutum were found to be infected 2 to 105 days post-infection with 3 to 103 (avg. 38) flukes in the small intestine. Worm wet weights averaged 0.6 mg at 9 days, 3.5 mg at 14 days, and 19 mg at 42 days; average dry weights for the identical days were 0.2, 1.2 and 5.8 mg, respectively. The average body length of worms fixed in hot (80 C) alcohol-formalin-acetic acid was 0.33 mm on day 2, 5.11 mm on day 10, 9.30 mm on day 42 and 8.56 mm on day 105. Body and gonadal area increased rapidly from about day 5 to 15 and then less rapidly. Eggs of E. revolutum were seen in the feces of 10% of the hamsters by day 9, 89% by day 10 and 100% by day 11. Eggs teased from worms, embryonated in tap water, and produced miracidia which infected lab-reared Helisoma trivolvis.     

Effects of a protein-free diet on worm recovery, growth, and distribution of Echinostoma caproni in ICR mice.

The effects of a protein-free diet on the host-parasite relationship of Echinostoma caproni in ICR mice were studied. The experimental diet was a customized protein-free diet (PFD) in pellet form containing 0% protein. The control diet consisted of a standard laboratory diet containing 23% casein as a source of protein. A total of 24 mice were each infected with 15 metacercarial cysts of E. caproni. Twelve mice were placed on the experimental diet (experimentals) and the remaining mice (controls) were placed on the control diet. Experimental and control mice were necropsied at 2, 3, and 4 weeks postinfection (p.i.). The weight of mice on the PFD was markedly lower than that of mice on the control diet. The length and circumference of the small intestine of infected mice on the PFD were significantly lower than those of the controls at 3 weeks p.i. (Student's t-test; P < 0.05). Worm recoveries from mice on the PFD were significantly lower than those of the controls at 3 weeks p.i. There was a significant decline in worm body area in worms from the mice on the PFD compared with those on the control diet at 2, 3, and 4 weeks p.i. Worm dry weights from mice on the PFD were significantly lower than those on the control diet at 2 weeks p.i. Worms from hosts on the PFD were located more posteriad in the gut than those recovered from mice on the control diet. The findings suggest that the PFD contributes to growth retardation of E. caproni in ICR mice.