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Biomedical subjects

V R Southgate

Publications and source records attributed to V R Southgate.

At least 19 recordsLinked to original sources
PubMed1995

Schistosoma mattheei infections in cattle: changes associated with season and age.

The Schistosoma mattheei egg output was monitored in 31 cattle over a 18-month period on a dairy farm near Lusaka (Zambia). The animals were kept on pasture with free access to two streams which were suitable for the intermediate host, Bulinus globosus. Individual faecal egg excretion reached an average peak of 130 eggs per gram, around 9 months after birth and decreased markedly before the age of 18 months. Average counts declined significantly with age, down to less than five eggs per gram in adult cows. A seasonal increase in B. globosus snails and S. mattheei transmission during the rainy season had no effect on the egg output of animals older than 18 months. Two calves and two adult cows were necropsied to compare fluke and tissue egg counts in young and old infections. There was a marked decline in tissue egg accumulation in older cows, in spite of an increase in the numbers of adult female flukes, as compared with young animals. A shift of egg accumulation from the large intestine towards the liver was also observed as infection progressed. It is concluded from the results of faecal egg counts that cattle reared under conditions of continuous challenge develop acquired resistance to S. mattheei infection within the first year following primary infection. Comparison of fluke and tissue egg counts in farm animals of different ages suggests the acquisition of an anti-fecundity effect as infection progresses.

Age Factors↗
PubMed1995

Comparative analyses of the neuropeptide F (NPF)- and FMRFamide-related peptide (FaRP)-immunoreactivities in Fasciola hepatica and Schistosoma spp.

Immunochemical techniques were used to determine the distribution, chemical characteristics and relative abundance of immunoreactivity (IR) to two native platyhelminth neuropeptides, neuropeptide F (NPF) (Moniezia expansa) and the FMRFamide-related peptide (FaRP), GNFFRFamide, in the trematodes, Fasciola hepatica and Schistosoma mansoni; the larger S. margrebowiei was used in the chemical analysis. Extensive immunostaining for the two peptides was demonstrated throughout the nervous systems of both F. hepatica and S. mansoni, with strong IR also in the innervation of muscular structures, including those associated with the egg-forming apparatus. The patterns of immunostaining were similar to those previously described for the vertebrate neuropeptide Y superfamily of peptides and for FMRFamide. Ultrastructurally, gold labelling of NPF- and GNFFRFamide-IRs was localized exclusively to the contents of secretory vesicles in the axons and somatic cytoplasm of neurones. Double-labelling experiments showed an apparent homogeneity of antigenic sites, in all probability due to the demonstrated cross-reactivity of the FaRP antiserum with NPF. Radioimmunoassay of acid-ethanol extracts of the worms detected 8.3 pmol/g and 4.7 pmol/g equivalents of NPF- and FMRFamide-IRs, respectively, for F. hepatica, and corresponding values of 4.9 pmol/g and 4.3 pmol/g equivalents for S. margrebowiei. Gel-permeation chromatography resolved IR to both peptides in discrete peaks and these eluted in similar positions to synthetic NPF (M. expansa) and GNFFRFamide, respectively.

Amino Acid Sequence↗
PubMed1994

Cattle schistosomiasis in Zambia.

A total of 358 cattle was examined for schistosome infection in Zambian slaughterhouses. A total of 542 worms collected from 104 infected individuals was examined for glucose-6-phosphate dehydrogenase and phosphoglucomutase using isoelectric focusing. The overall prevalence of infection was 51%. Ninety three percent of the infected animals had less than 100 worm pairs in the mesenteric veins. Schistosoma mattheei was the predominant species (75%); S. leiperi (12%) and S. margrebowiei (2%) were also identified. The remaining 11% of the worms showed one of two distinct heterozygote patterns. Pattern A is identical to that of a laboratory-produced F1 S. mattheei x S. haematobium hybrid, but could also represent a S. mattheei x S. leiperi hybrid. Further studies are required to elucidate the origins of pattern B.

Animals↗
PubMed1994

Studies on transmission and schistosome interactions in Senegal, Mali and Zambia.

The transmission and interaction of schistosomes in the Senegal River Basin in Mali and Zambia are reviewed and some preliminary field data are presented. In the Senegal River Basin four species of schistosomes are prevalent: Schistosoma mansoni, S. haematobium, S. bovis and S. curassoni as well as the following potential intermediate hosts: Biomphalaria pfeifferi, Bulinus globosus, B. umbilicatus, B. truncatus, B. senegalensis and B. forskalii. The role of each of these species in the transmission of schistosomes in man and domestic stock is discussed. Recent ecological changes caused by the construction of dams at Diama and Mananatali on the Senegal River, such as reduction in salinity, more stable water flow, creation of irrigation canals and development and extension of rice culture, have contributed towards the occurrence of new outbreaks of both intestinal and urinary schistosomiasis in the Senegal River Basin. In Mali, the four main areas of high prevalence of S. haematobium are Office du Niger (irrigation areas), Bandiagara (small dams), Selingué (dam areas) and Baguineda (irrigation areas). Apart from the Office du Niger, S. mansoni infections are rare. Surveys were carried out in the Dogon Country (Bandiagara District) in an attempt to confirm the recent independent reports of the presence of S. intercalatum. Data based on egg morphology and Ziehl Neelsen staining of egg shells suggested the possible occurrence of S. haematobium x S. intercalatum hybrids. Potential factors affecting the focal endemicity of S. haematobium in Mali are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

The in vitro transformation of the miracidium to the mother sporocyst of Schistosoma margrebowiei; changes in the parasite surface and implications for interactions with snail plasma factors.

The in vitro transformation of the miracidium to the mother sporocyst of Schistosoma margrebowiei was initiated by placing the miracidium in mammalian physiological saline. The transformation occurs in stages: the cilia cease beating; the ciliated plates become detached from the intercellular ridges and underlying muscle layers; the intercellular ridges spread over the body surface eventually forming a new tegument; the sporocyst changes from an ovoid to a tubular shape in about 48 h at room temperature. The surfaces of the miracidium, sporocyst and cercaria of S. margrebowiei display stage-specific carbohydrates on their surfaces as indicated by lectin staining. Ricin120 stains the cilia alone of the miracidium whereas peanut agglutinin stains the larval surface except for the cilia. The intercellular ridges of the miracidium stain with concanavalin A and wheat germ agglutinin, and these lectins stain the entire surface of the mature mother sporocyst. The cercaria is the only larval stage which stains positively with asparagus pea lectin. Bulinus nasutus is incompatible with Schistosoma margrebowiei; the haemolymph of this snail contains an agglutinin which agglutinates a wide variety of mammalian erythrocytes including those of human ABO blood groups. The haemagglutinin titre of B. nasutus plasma is reduced after incubation with miracidia of S. margrebowiei indicating that the agglutinin is absorbed onto the surface of this larval stage but not that of the mother sporocyst or cercaria. The possible roles of agglutinins in host-parasite interactions together with the significance of the differences in the surface carbohydrates of the larval stages are discussed.

Adsorption↗
PubMed1991

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↗
PubMed1991

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↗
PubMed1990

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↗
PubMed1990

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↗
PubMed1989

The influence of Calicophoron microbothrium on the susceptibility of Bulinus tropicus to Schistosoma bovis.

A total of 480 snails were collected from 3 habitats on the Mau Escarpment, Kenya, and were identified as Bulinus tropicus. Of the 351 snails examined alive in London, 75 were infected with Calicophoron microbothrium, 39 with C. microbothrium and Schistosoma bovis, 1 with S. bovis, 24 with other species of trematodes and 212 were uninfected. Examination of digestive glands of B. tropicus either uninfected or infected with both C. microbothrium and S. bovis demonstrated that it is possible to differentiate between parasite and host enzyme activity using glucose phosphate isomerase. However, malate dehydrogenase enables a much clearer differentiation between the enzyme activity of the schistosome and that of the amphistome. Laboratory snail infection experiments demonstrated that it is possible successfully to infect B. tropicus with S. bovis if the snails have previously been exposed to miracidia of C. microbothrium.

Animals↗
PubMed1989

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↗
PubMed1989

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↗
PubMed1988

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↗
PubMed1988

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↗
PubMed1987

Relationships between cercarial indices of Schistosoma haematobium, S. bovis and S. curassoni from Senegal and the isoenzyme genotypes of the adult worms.

S. haematobium and S. curassoni appear to consist of three and two G6PDH genotypes respectively whereas only a single genotype has been observed in S. bovis. This genotype corresponds to one of those exhibited by S. curassoni, but the two species may be distinguished using the AcP enzyme system. The antero-dorsal cercarial indices for S. haematobium gave a mean of 0.78 ranging from 0.67 +/- 0.03 to 0.90 +/- 0.11; S. curassoni gave a mean of 1.11, ranging from 1.00 +/- 0.05 to 1.23 +/- 0.14 and S. bovis a mean of 1.30 within the range 1.01 +/- 0.25 to 1.67 +/- 0.18. From these data it is apparent that there is some correlation between antero-dorsal Cl and enzyme genotype: nevertheless the variation in Cl is somewhat greater than that observed in enzyme genotypes. Generally, Cl values lower than 0.90 can be considered to be due to S. haematobium, those above 1.15 to be S. bovis and intermediate values of 0.90-1.15 indicate S. curassoni.

Animals↗