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PubMed1981

Schistosoma Weinland, 1858 from Hippopotamus amphibius Linnaeus, 1758 in the Kruger National Park.

Adults of Schistosoma edwardiense Thurston, 1964, were recovered from Hippopotamus amphibius in the Kruger National Park. Small round to oval Schistosoma margrebowiei-like eggs, presumed to be those of S. edwardiense, were found fairly frequently in the faeces of infected hippopotami together with a few Schistosoma haematobium-like eggs the identity of which remains uncertain. Biomphalaria sp., exposed to the droppings of infected hippopotami, shed cercariae thought to be those of S. edwardiense. No evidence of schistosoma adults was found at necropsy in rodents exposed to these cercariae. The parasite appears to be host specific to the hippopotamus. Arguments, based on biological and anatomical characteristics are put forward regarding Schistosoma hippopotami Thurston, 1963 as synonymous with Schistosoma mansoni.

Animals↗
PubMedDate not supplied

[Chaetotaxic variations of the miracidia of Schistosoma mansoni according to the adaptation to Muridae. Experimental and epidemiological data in Guadeloupe (author's transl)].

The "miracidial chaetotaxic index" of a human strain of Schistosoma mansoni from West-Africa displays an abrupt decrease following three first transmissions Biomphalaria pfeifferi, white mouse. Then it increases gradually up to a new balance. The value of the index permits to estimate the human or murine characteristic of the natural infections in Guadeloupe. According to stations the index of miracidia issued from rats is widely different. Stations where both rat and man are infected show strong differences from a station where infection seems exclusively murine (Grand-Etang). Results agree with these concerning cercariae. Possibility of intervention of murine strains infecting man in Guadeloupe and apt to cause an especially severe bilharziasis is called up.

Adaptation, Biological↗
PubMed1995

Worm development in hamsters infected with unisex and cross-mated Schistosoma mansoni and Schistosoma haematobium.

Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and in other areas in Africa, and people frequently are infected with parasites of both species. The effects of the interactions between worms of both sexes of the 2 species on development and egg laying were evaluated in vivo by infecting hamsters with cercariae from Biomphalaria alexandrina and Bulinus truncatus snails infected with single miracidia. In hamsters with unisex infections, male worms of both species were small. Schistosoma mansoni females were stunted and partially mature but did not contain eggs. Schistosoma haematobium females, though stunted, sometimes contained and laid small eggs, which were deposited in the liver, but few of which contained motile embryos. This suggests that unisexual infection with S. haematobium female worms produces a risk for liver damage due to egg deposition in tissues. Both S. mansoni and S. haematobium females that mated with males of the heterologous species were significantly larger than females from unisexual infections; they were sexually mature and possessed eggs in the uterus. The eggs in the liver homogenates of cross-specific infected hamsters contained fully developed miracidia that hatched in filtered pond water.

Animals↗
PubMed1993

Schistosomiasis and intestinal parasites in rural villages in southwest Nigeria: an indication for expanded programme on drug distribution and integrated control programme in Nigeria.

A cross sectional survey of schistosomiasis, intestinal parasite infections and pattern of schistosomiasis transmission was undertaken in four rural villages around the Erinle dam, Nigeria. The prevalence of Schistosoma haematobium ranged from 10% to 60%. 30% of infected school children excreted over 50 eggs/10 ml urine and high rates of haematuria, proteinuria, leucocyturia and nitrites in urine were observed in infected children and the villagers. Prevalence of infection with S. mansoni ranged from 11.4% to 36.8%. Intensity of infection based on geometric mean eggs/gram of faeces ranged between 100 and 545.7 eggs/g. Malacological surveys showed that Biomphalaria pfeifferi was the predominant potential snail hosts recovered at all the contact sites. Higher infections with schistosome parasites were also recorded for B. pfeifferi than Bulinus globosus. The pattern of transmission of schistosomiasis by the snails is consistent and makes incorporation of community-based focal application of a molluscicide such as Tetrapleura tetraptera in integrated control of schistosomiasis feasible in the area. Prevalence and intensity with Ascaris lumbricoides was high. The highest prevalence was 68.9% while the highest intensity of infection was 2,440.9 eggs/gram of faeces. Multiple infections occured with various combinations of Ascaris lumbricoides, hookworm, S. haematobium, Fasciola gigantica, S. mansoni, and Entamoeba histolytica (as double, triple or quadruple infections). The results suggest an integrated approach to the control of schistosomiasis and intestinal parasites in this part of the country.

Adult↗
PubMed1996

Schistosoma mansoni in migrants entering South Africa from Moçambique--a threat to public health in north-eastern KwaZulu-Natal?

OBJECTIVES: To identify possible public health consequences of Schistosoma mansoni infections in migrants entering north-eastern KwaZulu-Natal and Mpumalanga and Northern Province from southern Moçambique. DESIGN: (i) Intestinal parasite surveys, one sample per person, within a 4-month period; (ii) temperature recordings and snail collections in an irrigation system. SETTING: North-eastern KwaZulu-Natal and Kruger National Park, Mpumalanga and Northern Province. PARTICIPANTS: Ninety-seven migrants (1-68 years) from north-eastern KwaZulu-Natal and 47 from the Kruger Park (1 - 70 years). MAIN OUTCOME MEASURES: The relatively high S. mansoni prevalence may cause problems on the rice paddy scheme in north-eastern KwaZulu-Natal. Ranges and prevalence rates of other parasites were recorded. RESULTS: S. mansoni prevalence in Moçambicans entering north-eastern KwaZulu-Natal was 14.4%, seven times more than in local residents. S. mansoni is not endemic to this region because most bodies of water become too warm for either the parasite or its snail host, Biomphalaria pfeifferi, to develop. Recordings in paddies suggest, however, that the rice modifies the temperature pattern as it grows and provides a suitable habitat for transmission. Migrants entering the Transvaal lowveld where S. mansoni is endemic may become more severely infected. Thirteen other parasite species were recorded from migrants entering KwaZulu-Natal and 8 from those entering Mpumalanga and Northern Province. CONCLUSIONS: The relatively high S. mansoni prevalence among migrants entering north-eastern KwaZulu-Natal may have public health implications as it could encourage transmission in a non-endemic area. The range of parasites carried by migrants entering KwaZulu-Natal, Mpumalanga and Northern Province was similar to that harboured by local people but prevalence rates were generally lower.

Adolescent↗
PubMed1995

From Polyplacophora to Cephalopoda: comparative analysis of nitric oxide signalling in mollusca.

The distribution of putative nitric oxide synthase (NOS)-containing cells has been analysed using NADPH-d histochemistry in the CNS and peripheral tissues in more than 2D ecologically and systematically different molluscan genera representing 3 main classes of the phylum MOLLUSCA: Polyplacophora (Lepidopleurus, Lepidozona, Katharina), Gastropoda (Littorina, Lymnaea, Aplexa, Physa, Planorbarius, Planorbis, Helisoma, Biomphalaria, Helix, Limax, Cepaea, Bulla, Aplysia, Phyllaplysia, Philine, Pleurobranchea, Tritonia, Armina, Flabellina, Cadlina) and Cephalopoda (Octopus, Sepia, Rossia, Loligo). Several species were used for more detailed immunohistochemical, biochemical, biophysical and physiological studies to further assay of NOS activity and to analyse functional roles of nitric oxide (NO) in these animals. The main conclusions of our comparative analysis and literature survey can be summarised as following: (i) There is strong evidence for the presence of NO-dependent signalling pathways in different molluscan species. (ii) We hypothesise that a general tendency in the evolution of NADPH-d-reactive cells in Mollusca is a migration of nitrergic function from periphery to the CNS. Also, different isoforms of NOS appear to be present in any one species. (iii) One of the main functional targets of NO signalling is the feeding system. However, there are obvious differences between predators (many labelled central motoneurons) and herbivorous species (many labelled peripheral putative sensory cells) as well as between land/freshwater and marine animals. Nevertheless, in all species tested NO-activated feeding-like motor patterns in the buccal ganglia. Additional functional and cellular targets for NO in molluscs are also considered. We briefly review neuromodulatory mechanisms of NO action and we consider molluscs as useful model systems for investigations of the roles of NO.

Animals↗
PubMed1996

Transmission of intestinal schistosomiasis in Addis Ababa, Ethiopia.

Malacological and parasitological surveys were made in Bole-Kotobe area in Addis Ababa in April 1996 to investigate the transmission of intestinal schistosomiasis. Malacological survey conducted in Kotobe river showed Schistosoma mansoni cercarial infection rate of 2.6% (one out of 38) in Biomphalaria pfeifferi. In a total of 197 stool specimens from school children examined using Kato thin smear method in Misrak Bar Number 1 and Wondirad Elementary and Junior Secondary Schools, the overall prevalence rate of Schistosomas mansoni was 4% and 10%, respectively while the intensity of infection was 66 and 37 eggs per gram (EPG) of stool, respectively. Out of the 13 children found infected in the two schools, nine gave a history of having swam in Kotobe river and had never been outside of Addis Ababa since birth. The collection of B. pfeifferi infected with S. mansoni, the establishment of the isolated S. mansoni in laboratory mice and the finding of schistosome infected children who had never been outside of Addis Ababa confirmed that transmission of intestinal schistosomiasis is actually taking place in Addis Ababa. Further surveys in other water-bodies in the city for mapping of schistosomiasis infection sites and transmission foci are recommended to enable immediate control measures before the situation gets out of control.

Adolescent↗
PubMed1998

Comparative observations on cercariae and metacercariae of Echinostoma trivolvis and Echinoparyphium sp.

Comparative observations were made on cercariae of Echinoparyphium sp. from Physa gyrina in Charlie's pond, Stokes County, North Carolina and cercariae of Echinostoma trivolvis from Helisoma trivolvis in Northampton County, Pennsylvania. The cercaria of Echinoparyphium sp. has 43 collar spines, lacks penetration and paraesophageal glands, and has a conical tail without fin folds. The cercaria of E. trivolvis has 37 collar spines, penetration and paraesophageal glands, a finger-like process at the tip of the tail and fin folds. The length of the cercarial body and tail of E. trivolvis was significantly greater than that of Echinoparyphium sp. Cercariae of both species encysted in Biomphalaria glabrata snails in single and concurrent infections. In concurrent infections with a single cercaria of each species, 2 encysted metacercariae were adjacent to each other in the saccular kidney of the snail at 24 hr postinfection. The diameter of encysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp. Echinoparyphium sp. metacercariae excysted at 39 C in an alkaline trypsin-bile salts medium used previously to excyst E. trivolvis. The length of excysted metacercariae of E. trivolvis was significantly greater than that of Echinoparyphium sp.

Animals↗
PubMed1999

Molluscicidal constituents of Marsypianthes chamaedrys.

Marsypianthes chamaedrys is a common herb that occurs in the North and Northeast regions of Brazil. Phytochemical studies showed this plant to be rich in triterpenoids. The hexane extract of M. chamaedrys yielded, after chromatographic separations, two mixtures: the first containing monohydroxylated-compounds (alpha-amyrin, beta-amyrin, lupeol and germanicol) and the second, dihydroxylated compounds (chamaedrydiol, castanopsol, 2alpha-hydroxylupeol and epigermanidiol). Molluscicidal tests were performed for the crude hexane extract and for mixtures I and II. Mixture II showed high activity.

Animals↗
PubMed1998

Failure of P strain mice to respond to vaccination against schistosomiasis correlates with impaired production of IL-12 and up-regulation of Th2 cytokines that inhibit macrophage activation.

In contrast to most inbred strains, P mice fail to develop significant resistance to Schistosoma mansoni infection as a result of vaccination with either radiation-attenuated cercariae or schistosome antigens plus Bacillus Calmette Guérin, and this failure correlates with defects in macrophage larvicidal activity. Supernatant fluids from antigen-treated in vitro cultures of splenocytes from vaccinated P mice demonstrate less macrophage stimulatory activity than do supernatants from cells of vaccine-responsive strains such as C57BL/6. This is not due either to diminished production of the macrophage-activating cytokine IFN-gamma by P mice, or to a lesser responsiveness of macrophages from P mice to activation by IFN-gamma. Rather, P splenocytes produce two-to threefold higher amounts of IL-4 and IL-10, cytokines which down-regulate the cytotoxic potential of IFN-gamma-treated macrophages. Thus, the macrophage-activating potential of cytokine preparations from vaccinated P mice can be completely recovered by in vitro treatment with antibodies to IL-4 or IL-10. Moreover, lower levels of IL-12, a cytokine involved in promoting development of Th1 responses, are produced by splenocytes from P mice as compared to C57BL/6 counterparts. These studies indicate that a genetic predisposition toward an impaired production of IL-12 and an increased production of down-regulatory Th2 cytokines correlate with low response to vaccination against S. mansoni.

Animals↗
PubMed1993

Synthesis and molluscicidal activity of new derivatives of 1-(hydroxy/substituted phenyl)-3-arylpropenones.

Several 1-(hydroxy/substituted phenyl)propenones were tested as molluscicidal agents among which the 1-(2-hydroxy/substituted phenyl)-3-(2-furyl)propenones 1a-c show the most promising results. In an attempt to improve their activity, new dihydropyrazolo[1,5-c][1,3]benzoxazines, their thio and their dehydrogenated derivatives were prepared. The pyrazolo[1,5-c][1,3]benzoxazines 4a,b were hydrolyzed affording the 3-(2-furyl)-5-(2-hydroxy/substituted phenyl) pyrazoles 8a,b. The hydroxyimino derivatives 10a-c were synthesized together with their corresponding isoxazole derivatives 11a-c. -Molluscicidal assay indicated that the oximes 10b,c, the isoxazole 11b, the pyrazole 8b, and its N-carbamoyl derivative 9b are most effective. They have in common the conjugated system shown in Fig. 1 which is presumably the active core.

Animals↗
PubMed1994

Salicylamides containing amino acid or pyran moieties with molluscicidal activity.

Salicylamide amino acid conjugates were prepared utilizing 5-formyl-, 5-dicyanoethenyl-, and 5-nitroethenylsalicylic acid. 5-Substituted salicylanilides were treated with glycine and formaldehyde in a Mannich type reaction affording the corresponding 3-(N-glycino)salicylanilides. The reactions of anilines with pyrans containing the salicylyl moiety yielded the corresponding salicylanilides. The obtained compounds were tested for molluscicidal activity.

Amino Acids↗
PubMed2005

A novel synthesis and molluscicidal activity of some functionally substituted pyridine, pyrido[3,2-c]pyridazine, and pyrido[3,2-c]pyridazino[2',3'-a]quinazoline derivatives.

Ethyl benzoylacetate reacts with the malononitrile dimer to afford 4-amino-5-benzoyl-2-dicyano methyl-6-hydroxypyridine, which undergoes the coupling reaction with aromatic diazonium salts to afford azo derivatives. These azo derivatives could be cyclized into pyrido[3,2-c]pyridazine and pyrido[3,2-c]pyridazino[2',3'-a]quinazoline derivatives upon reflux in ethanolic NaOH, presumably via their hydrazo tautomers. The molluscicidal activity of these compounds was evaluated.

Animals↗
PubMed1980

Effector mechanism in the response of Schistosoma mansoni miracidia to snail-conditioned water.

Schistosoma mansoni miracidia respond to snail-conditioned water (SCW) by sharply increasing their rate of turning when they encounter abrupt decreases in stimulant concentration (Roberts et al., '79). We examined the role of the cilia and the subepithelial muscles in the turning behavior of stimulated miracidia. Several lines of evidence indicated that miracidia do not turn by altering their ciliary beat. Ciliary beating on detergent-treated miracidia was reactivated using solutions containing ATP and Mg2+. These organisms were unable to turn spontaneously, a characteristic of live miracidia. Several divalent cations which stimulate increased turning of intact miracidia failed to support ciliary reactivation of detergent-treated organisms. Further, intact miracidia increased their rate of turning in gradients of Mg2+, but detergent-treated organisms swimming in reactivation solution did not turn in Mg2+ gradients. High speed cinematography of intact miracidia swimming in gradients of SCW or Mg2+ illustrated that turning is invariably accompanied by flexion of the body. This bending occurred only at the transverse interciliary ridges between the first and second, and second and third tiers of ciliated plates. Flexion was not observed at the interciliary ridge between the third and fourth tiers of plates, suggesting that miracidia turn by contracting specific portions of their subepithelial musculature.

Adenosine Triphosphate↗
PubMed1993

Schistosoma mansoni: an enkephalinergic system that may participate in internal and host-parasite signaling.

The present study is concerned with an opioid system in the human trematode Schistosoma mansoni, both as part of the endogenous chemical messenger system and as a tool in the parasite reaction to the host(s). A high-affinity opioid binding site was characterized in membrane suspensions prepared from adult worms. Scatchard analysis revealed a single class of receptors with a dissociation constant of 1.8 nM and a Bmax of 24.9 pmol/g protein for (D-Ala2, Met5)-enkephalin (DAME). The displacement experiments demonstrated that the most potent ligands were beta-endorphin, DAME, and met-enkephalin. These characteristics and the effects of various ions on DAME affinity suggest that S. mansoni has a delta-like opioid receptor, as previously described in other invertebrates. A met-enkephalin-like peptide was also characterized in a miracidial extract. Radioimmunoassay, reverse-phase HPLC, and bioassay by induction of cell conformational changes of human polymorphonuclear leukocytes revealed that the parasite peptide is very similar to authentic met-enkephalin. A met-enkephalin-like peptide was also shown to be present in adult worms and in their incubation medium. Taken together, these observations demonstrate the existence of a complete opiate system in S. mansoni. We discuss its role in molecular signaling within the parasite and in host-parasite interactions.

Animals↗
PubMed1995

Schistosoma mansoni: characterization of excretory-secretory polypeptides synthesized in vitro by daughter sporocysts.

Excretory-secretory (ES) products of daughter sporocysts have been implicated in the modulation of snail host reproductive physiology. Because of the potentially important role of ES products in snail reproduction, newly synthesized ES polypeptides of in vitro-cultured Schistosoma mansoni daughter sporocysts were examined in pulse-chase studies using [35S]methionine followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), fluorography, and scanning densitometry. Fluorograms of SDS-PAGE-separated ES proteins revealed that sporocysts released a wide variety of polypeptides ranging in molecular weight from 17 to 200 kDa into supernatants during 6 days of in vitro culture at 26 degrees C. Moreover, the general pattern of synthesis and release of daughter sporocyst polypeptides into culture supernatants differed from those ES components previously described from primary or mother sporocysts. Although quantitative densitometry revealed that total labeled ES protein released into culture supernatants was consistent for all three pulse-chase periods, there were significant differences in the quantities of individual polypeptide peaks. The dynamics of the synthesis and release of eight polypeptides chosen for further analysis varied over time. Several ES polypeptides (110, 95, and 25 kDa) were released in relatively constant amounts, while some (69 and 44 kDa) increased and others (38 and 35 kDa) decreased in quantity over the same period of culture. It is hypothesized that the 38- and 35-kDa polypeptides may be important candidate inhibitory molecules because of the correlation between their early release into culture supernatants and the inhibitory effect of Day 1-2 daughter sporocyst ES products on polysaccharide synthesis in the albumen gland of the snail host.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗