Histopathologic findings of Schistosoma margrebowiei in experimentally infected laboratory animals.
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Animals↗
Biomedical subjects
D Rollinson
Publications and source records attributed to D Rollinson.
Sequence of a small subunit rRNA gene of Schistosoma mansoni and its use in phylogenetic analysis.
The complete sequence of a small ribosomal RNA gene of Schistosoma mansoni contained within plasmids pSM389 and pSM889 is presented. It was found to be 1992 bp in length, larger than that of most eukaryotes. Extra nucleotides occur in regions known to be variable (V4 and V7). The predicted secondary structure of the nucleotides 660-853 revealed additional helices which have been designated E21-1A and E21-1B. The other region to differ from higher eukaryotes lies between nucleotides 1457 and 1569. Secondary structure prediction demonstrated that a single extended helix may be formed from this part of the schistosome small subunit rRNA sequence. Nucleotides that could be unambiguously aligned with those of 12 other eukaryotes were used to estimate phylogenetic relationships. The consensus tree obtained by Maximum Parsimony analysis showed the schistosome as a sister taxon to the flatworm Dugesia tigrina.
Amino Acid Sequence↗
Studies of the relationships between Schistosoma nasale and S. spindale and their snail host Indoplanorbis exustus.
Infectivity and cercarial production of Indoplanorbis exustus related to variation of miracidial dose (1, 4, 10 or 20) with Schistosoma nasale and S. spindale from Sri Lanka were studied. The intermediate host-parasite relationships of the two schistosome species showed marked differences under the conditions of observation recorded in this study. Prepatent death rates (PDR) were on average higher for S. spindale (30%) than for S. nasale (10%). The size of the miracidial dose to which snails had been exposed had no effect on PDR. The infection rates (IR) were on average higher for S. nasale (41%) compared with S. spindale (27%). Highest IR occurred after exposure to 4 miracidia in S. nasale infections (79%) and after exposure to 10 miracidia in S. spindale infections (60%). The highest daily average cercarial production per snail was recorded for S. nasale at a level of 4 miracidia (1311), and for S. spindale at a level of 10 miracidia (1615). At low level (1 or 4 miracidia) of exposure, I. exustus showed a better compatibility with S. nasale than with S. spindale. An opposite tendency was observed at higher levels (10 or 20 miracidia) of exposure. Unsuccessful infections of Lymnaea luteola with either S. nasale or S. spindale indicate that this species is not involved in transmission.
Animals↗
The epidemiology of Schistosoma spindale Montgomery, 1906 in cattle in Sri Lanka.
During 1988 and 1989, the mesenteric veins of 901 cattle were examined for the presence of schistosomes at the Kandy slaughterhouse (Sri Lanka). The overall prevalence of infection was 31.2%. Animals younger than 2 years were less infected (21.3%) than those older than 5 years (47.9%). Based on the number of paired worms counted, three intensities of infection were recognized: low (1-20 pairs), moderate (21-100 pairs) and heavy (greater than 100 pairs). Intensities increased with the age of the animals but remained low (average 10 worm pairs). The worm burden increased by approximately 20% for each step in age group. The number of miracidia/100 g faeces was measured in 85 animals of all age groups and intensities of infection; 77% of the samples contained less than 100 miracidia. Miracidia counts decreased with age; moderately and heavily infected animals in each age group had the highest and the lowest counts, respectively. This may be due to a host immune response. The results raise questions on the sensitivity of faecal egg counts as a diagnostic method for visceral schistosomiasis in cattle.
Abattoirs↗
Development of cloned DNA probes for the identification of snail intermediate hosts within the genus Bulinus.
DNA fragments have been isolated from Bulinus cernicus and cloned in Escherichia coli strain JM109 using pUC18 as the vector. Four recombinant plasmids designated pBC123, pBC126, pBC127 and pBC134 were selected for further analysis and were shown by both dot and Southern blot hybridisations to have different specificities to species representing the four species groups of Bulinus. Non-specific hybridisation occurred with pBC126 whereas pBC123 and pBC134 hybridised only to B. cernicus. Partial restriction maps of the inserts revealed sequence differences between pBC123 and pBC134. Intermediate specificity was shown by pBC127 as this probe hybridised only to DNA from snails of the B. forskalii group and B. truncatus of the B. truncatus/tropicus complex. The results demonstrate the potential of DNA probes for the identification and characterisation of intermediate hosts of schistosomes.
Animals↗
Observations on natural and experimental interactions between Schistosoma bovis and S. curassoni from West Africa.
Surveys of 332 naturally infected bovines at eight abattoirs in Senegal, The Gambia and Mali were carried out to determine the prevalence of infection with Schistosoma bovis and S. curassoni and to pinpoint areas where the distribution of the species overlap. S. bovis was the commonest schistosome of cattle in Senegal and Mali being found in animals at seven abattoirs, the highest prevalence of 85.1% occurred at Mopti in Mali. S. bovis was the only bovine schistosome observed in The Gambia. S. curassoni was isolated from a cow at Bamako and shown to have similar glucose-6-phosphate dehydrogenase, phosphoglucomutase and acid phosphatase profiles to those described for a Senegalese isolate. Evidence of interaction of S. bovis with S. curassoni was found in cattle from Senegal, at Tambacounda and Kolda, and from Mali, at Bamako and Mopti. A mixed experimental infection of both species in a sheep showed the lack of any specific mate recognition system: identification of the worms was facilitated by analysis of acid phosphatase by isoelectric focusing in polyacrylamide gels. Viable hybrid parasites were produced in the laboratory and were maintained up until the F4 generation. Comparisons of egg morphology, surface structure of adult male worms and enzyme profiles have been made between experimental hybrid lines and field isolates. Possible mechanisms maintaining species integrity are discussed.
Abattoirs↗
Pathology of natural infections of Schistosoma spindale Montgomery, 1906, in cattle.
The pathology of natural Schistosoma spindale infections in cattle in Sri Lanka was studied. Hepatic lesions were moderate with periportal cell infiltration and periportal epithelioid cell granulomas within perilobular zones. Submucosal and mucosal granulomas accompanied by cellular changes were present in the small and large intestine. Two unusual observations included the migration of an adult worm from the mesenteric veins to the mucosa of the small intestine in one bull and the presence of epithelioid cell granulomas containing slender living eggs in the urinary bladder of one animal. Intensities of infections, histopathological changes and immunological responses are discussed and comparison is made with other schistosome species.
Animals↗
Hybrids between Schistosoma mansoni and S. rodhaini: characterization by isoelectric focusing of six enzymes.
Results are reported of enzyme analyses by isoelectric focusing in polyacrylamide gels of individual extracts from Schistosoma mansoni (Guadeloupe), S. rodhaini (Burundi), and their experimental hybrids (first and second generation). The distinctive patterns of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G6PD), acid phosphatase (AcP), phosphoglucomutase (PGM) and glucose phosphate isomerase (GPI) enable the characterization of the two parental strains and the hybrids. Particular observations, such as the existence of a polymorphism at both MDH-1 and MDH-2 loci and a sex-linked heredity for GPI, are discussed. A genetic interpretation is proposed to explain the patterns observed for MDH and GPI (with a dimeric structure) and for PGM (monomeric structure); a comparison is made with electrophoretic data available for S. mansoni and S. rodhaini.
Acid Phosphatase↗
Experimental chemotherapy of Schistosoma curassoni in mice.
Mice experimentally infected with Schistosoma curassoni were treated with different dose regimens of praziquantel, metrifonate, oxamniquine and hycanthone. Praziquantel was the most effective drug; a dose of 100 mg/kg given orally for 5 days resulted in a 95% reduction in worm burdens. The drug produced oogram changes in all animals. Metrifonate did not result in a reduced worm burden but caused oogram changes even on a low-dose (150 mg/kg during 2 consecutive days) schedule. Oxamniquine proved to be ineffective; no reduction in worm burdens or alterations in oograms were observed. Hycanthone (80 mg/kg for 1 day) resulted in a significant reduction in worm burdens.
Animals↗
A DNA probe from Schistosoma mansoni allows rapid determination of the sex of larval parasites.
A DNA clone representing a 0.4 kb degenerative repeat has been isolated. The DNA sequence is present only in the genome of female Schistosoma mansoni at different stages of the life cycle, at a frequency of approximately 75 copies per adult female genome. The sequence is not expressed and probably represents satellite DNA in the heterochromatin region of the W chromosome. It is demonstrated that the DNA clone may be used for the rapid determination of the sex of cercariae without the need for DNA isolation or Southern blotting.
Animals↗
Differentiation of Schistosoma mansoni from S. rodhaini using cloned DNA probes.
The ribosomal RNA (rRNA) gene units of Schistosoma mansoni and S. rodhaini, of the lateral spined egg group, have been studied. The schistosome rRNA gene unit consists of a regular interspersion of the two genes encoding the large and small rRNA units with two spacers. The large spacer is not transcribed while the small spacer is part of the transcription unit. Variation in the rRNA gene unit between the two species is demonstrated to take the form of loss or gain of restriction sites within the non-transcribed and transcribed spacers. This variation has been demonstrated to enable the differentiation of S. mansoni from S. rodhaini by Southern hybridization analysis. In addition, a DNA clone representing a female specific, tandemly repeated sequence, is demonstrated to enable differentiation of S. mansoni and S. rodhaini using dot blot hybridization analysis.
Animals↗
The prevalence and pathology of Schistosoma nasale Rao, 1933 in cattle in Sri Lanka.
During 1987 a total of 1393 cattle was examined for Schistosoma nasale infection at the Kandy slaughterhouse, Sri Lanka. The overall prevalence was 12.6% (monthly range 3-17%). Based on the appearance of macroscopic lesions, 6 types (0-5) were recognized; type 5 being the most severe, with cauliflower-like growths obstructing the nasal cavity. Older bovines with 8 permanent incisors were more heavily infected (29.1%) than younger ones with no permanent incisors (6.0%). The severity of the lesions increased also with the age of the animals. Observations on the localization of the lesions showed that the first sessile nodular areas appear on the medial septum, on the dorsal edge of the ventral nasal concha and on the lateral wall of the middle meatus of the nasal cavity. Later, they gradually spread over the whole mucosal surface of the anterior part of the cavity but were rarely found further than 10 cm posterior to the nasal opening. The histopathology showed that granuloma formation due to the presence of eggs was the most common feature of the respiratory mucosa.
Abattoirs↗
The effect of praziquantel on Schistosoma nasale infections in cattle.
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Animals↗
Schistosoma curassoni Brumpt, 1931 and S. bovis (Sonsino, 1876) in cattle in northern Nigeria.
Schistosoma curassoni has been recovered from cattle in northern Nigeria. Rectal scrapings of 90 cows slaughtered at the Kano abattoir, Kano, Nigeria during March and April 1986 revealed a prevalence of 7.8% S. bovis and 2.2% S. curassoni. Further examination of the mesenteric and rectal veins of 502 cows showed that the overall prevalence of schistosomiasis was 31.1%. Local Bulinus globosus were infected successfully in the laboratory with s. bovis miracidia.
Abattoirs↗
Observations on the infectivity and fecundity of Schistosoma curassoni from Senegal in albino mice.
An average of 11% of adult Schistosoma curassoni were recovered from 200 albino mice which had been infected subcutaneously with 150-250 cercariae. Worms were primarily found in the portal veins. The average number of intrauterine eggs per female during the first 100 days p.i. was 13 and the average number of eggs produced per female worm was 103 per day for the first 60 days post oviposition. The majority of eggs were recovered from the liver (98.3%). The oograms were determined until day 95 p.i. For screening of antischistosomal drugs it is recommended not to use infections older than 60 d.p.i.
Animals↗
Clinical pathology of experimental Schistosoma curassoni infections in sheep and goats.
The clinical pathology of Schistosoma curassoni infection in sheep and goats was studied for 22 weeks following experimental infection with 7000 and 4000 cercariae, respectively. Excretion of eggs began at week 7 after infection: in goats the numbers increased to 30 to 50 eggs per gram faeces (epg) at weeks 8 to 18, followed by a reduction. In a pregnant goat, epg values increased markedly before and after parturition. The mean faecal egg counts in sheep were lower than in goats, increasing to a maximum level of 30 epg at weeks 16 and 17 after infection. Infected sheep maintained growth rates roughly comparable with controls, whereas infected goats failed to gain as much weight as the controls. Infected goats and sheep produced eosinophil counts of about 3 x 10(3) mm-3, five and eight weeks after infection, respectively. Sheep developed a progressive anaemia from week 11 after infection, in goats blood values remained within normal limits. Differences in serum protein concentration were observed between infected and uninfected goats about nine weeks after infection, but not in sheep. Increased total protein values, hyperglobulinaemia and lowered albumin to globulin ratios were features of infected goats. Serum glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, gamma-glutamyl transferase, total lactate dehydrogenase and bilirubin were not significantly changed. The mean recovery in sheep was 608 worms, in goats 428 worms, but the total tissue egg counts were higher in the latter. Of the total eggs deposited in the goats 92 per cent were found in the liver with 51.5 per cent in the ovine liver. The histopathological changes were studied.
Animals↗
Differentiation of Schistosoma haematobium from related species using cloned ribosomal RNA gene probes.
The ribosomal RNA (rRNA) gene units of Schistosoma mansoni (lateral spined eggs) and six species of schistosomes with terminal spined eggs (S. haematobium, S. curassoni, S. bovis, S. intercalatum, S. margrebowiei and S. mattheei) have been studied. The schistosome rRNA gene unit consists of a regular interspersion of the two genes encoding the large and small rRNA units with two spacers. The large spacer is not transcribed while the small spacer is part of the transcription unit. Variation in the rRNA gene unit of the species studied is demonstrated and takes three forms: First, variation in DNA sequence leads to both reduced homology in the spacer regions between species and loss or gain of restriction sites. Second, variation in the length of the transcribed spacer is demonstrated and DNA insertions of 0.2 kilobases (kb) and 0.1 kb are observed in S. mattheei and S. margrebowiei, respectively. Third, the length of the non-transcribed spacer region varies between species. S. haematobium has a 0.5 kb deletion in this region, while that of S. margrebowiei contains varying numbers of a 0.4 kb DNA insert. These interspecific variations have been shown to be conserved within species. Analysis of the rRNA genes by DNA hybridisation techniques therefore serves as a means of species identification, whereby it is possible to differentiate S. haematobium from other schistosome species with terminal spined eggs. Similarly, S. margrebowiei and S. mattheei may be clearly distinguished, although no major variation has been detected between S. curassoni, S. bovis and S. intercalatum. All these species differ from S. mansoni by the absence of certain restriction sites in the non-transcribed spacer.
Animals↗
Schistosoma mansoni from naturally infected Rattus rattus in Guadeloupe: identification, prevalence and enzyme polymorphism.
An enzymatic comparison has been made between isolates of Schistosoma mansoni from rats and humans in Guadeloupe and a Burundi isolate of S. rodhaini. Analyses of LDH, MDH, AcP, PGM, GPI, G6PDH and HK by isoelectric focusing provided no evidence for the involvement of S. rodhaini in the recent evolution of the schistosomes currently endemic in Guadeloupe. No distinction could be made between murine and human isolates of S. mansoni and it is suggested that murine schistosomiasis should not therefore be ignored in control programmes. Rattus rattus were captured at seven sites around the island; of 142 examined, 48 were positive for schistosomes. Differences in prevalence between habitats were marked and only small changes in prevalence were observed in localities sampled in 1982 and 1983. Animals with the greatest worm burdens were associated with areas of high prevalence, and age-related changes in worm burden were observed. Two alleles, a and b, at the MDH-1 locus of S. mansoni from rats were identified. Differences in the overall frequencies of these alleles were observed for schistosomes from different localities. Allelic frequencies representative of schistosomes from rats at four localities were stable from 1982 to 1983. The majority of positive animals, even those with light worm burdens, were found to be infected with a number of different schistosome genotypes.
Alleles↗