Disease Schistosomiasis Research Articles

Rapid, Simple, and Sensitive Immunoagglutination Assay with SiO2 Particles and Quartz Crystal Microbalance for Quantifying Schistosoma japonicum Antibodies

The resurgence of the parasitic disease schistosomiasis calls for more efficient diagnostic tests. We developed a rapid, simple, portable, and sensitive immunoagglutination assay that uses SiO(2) particles and quartz crystal microbalance (QCM) for quantifying Schistosoma japonicum (Sj) antibodies (SjAb). We prepared submicrometer-sized silica particles derivatized with Sj antigens as replacements for traditional latex microspheres to specifically agglutinate in the presence of SjAb targets, and we used the QCM monitor to measure the resulting frequency shifts. We optimized the assay medium by adding poly(ethylene glycol) (PEG) as a response accelerator of immunoagglutination. To minimize or eliminate any nonspecific agglutination or adsorption interferences, we conducted appropriate sealing procedures separately for silica particles and the QCM probe. The measured frequency changes were linearly related to the SjAb concentrations in infected rabbit serum. The PEG-assisted immunoagglutination system was quantitatively sensitive to SjAb concentrations ranging from approximately 0.70 to 32.31 mg/L, with a detection limit of approximately 0.46 mg/L. The obtained linear regression equation was: y=43.61 x+80.44 (r=0.9872). Several serum specimens were evaluated with the developed QCM immunoassay and the results were compared with ELISA, validating the feasibility of practical applications. This novel immunoagglutination-based QCM detection format is rapid, simple to use, and more portable than conventional diagnostic immunoassays, thus offering a promising alternative tool that can be used for point-of-care clinical diagnosis of schistosomiasis, particularly in epidemic situations.

Histologic Study of Colonic Mucosa in Patients With Chronic Diarrhea and Normal Colonoscopic Findings

There are controversies about the importance of biopsies of normal colon mucosa in the investigation of patients with chronic diarrhea. Colonic and terminal ileum biopsies of 167 patients were reviewed. In 5 patients, used as controls, colonoscopy was done due to family history of colon cancer. The 5 patients without symptoms had no histologic abnormalities. The histologic findings in 162 patients with chronic diarrhea were as follows: 110 patients (67.9%) with normal histology, microscopic colitis not otherwise specified, and isolated small granulomas; 17 (10.5%) patients had findings of borderline diagnostic significance, including possible collagenous colitis, some features of lymphocytic colitis and melanosis coli; and 35 (21.6%) patients, with diagnostic significant histologic findings as collagenous colitis, lymphocytic colitis, minimal change microscopic colitis, eosinophilic colitis, pericrypt eosinophilic enterocolitis, intestinal spirochetosis, schistosomiasis, and Crohn's disease. Of the 52 patients with either borderline or significant diagnostic abnormalities, in 8 (15.4%) the diagnosis was done only with a proximal study (ascending, transverse, or descending colons). Histologic lesions of possible diagnostic value could exist in 32.1% of chronic diarrhea patients with normal colonoscopy, which can justify, in certain cases, mucosa biopsies, which might contribute for a more precise etiologic diagnosis; also, the distribution of these histologic changes has pointed out the importance of having all colon segments biopsied.

Diseases and therapies in ancient Egypt: what can mummies and other human remains tell us?

Mummies and skeletal material of ancient Egypt constitute valuable sources for paleopathological studies when using classical methods or modern investigation tools such as imaging techniques or molecular biology. From these approaches, we improve our knowledge about the conditions and the duration of life, eating habits, or mummification techniques. A compilation of the main diseases found during these periods can be made. One must underline the similarity in health problems with present times concerning, for instance, tuberculosis, parasitic diseases (schistosomiasis, malaria, dracunculosis), osteoporosis, arteriosclerosis, skin diseases, or dental problems. Conversely, no case of syphilis was found. The real frequency of malignant tumours remains a controversial topic. Considering therapeutic armamentarium, findings such as amputations, prosthetic replacements or more sophisticated surgery must be combined with data provided by medical papyri or carvings. This approach contributes to a better understanding of the evolution of disease and the history of medicine.

713 ORAL Interruption of Imatinib (IM) in responding patients after one year treatment does not influence overall survival of patients with advanced GIST: Updated results of the French Sarcoma Group randomized phase III BFR14 trial

In the search for new drugs and drug targets to treat the flatworm disease schistosomiasis, protein kinases (PKs) have come under particular scrutiny because of their essential roles in developmental and physiological processes in schistosome parasites. In this context the application of the anti-cancer Abl tyrosine kinase (TK) inhibitor Imatinib (Gleevec/Glivec; STI-571) to adult Schistosoma mansoni in vitro has indicated negative effects on diverse physiological processes including survival.Motivated by these in vitro findings, we performed in vivo experiments in rodent models of S. mansoni infection. Unexpectedly, Imatinib had no effect on worm burden or egg-production. We found that the blood components serum albumin (SA) and alpha-1 acid glycoprotein (AGP or orosomucoid) negated Imatinib’s deleterious effects on adult S. mansoni and schistosomula (post-infective larvae) in vitro. This negative effect was partially reversed by erythromycin. AGP synthesis can increase as a consequence of inflammatory processes or infection; in addition upon infection AGP levels are 6–8 times higher in mice compared to humans. Therefore, mice and probably other rodents are poor infection models for measuring the effects of Imatinib in vivo. Accordingly, we suggest the routine evaluation of the ability of AGP and SA to block in vitro anti-schistosomal effects of small molecules like Imatinib prior to laborious and expensive animal experiments.

Urinary schistosomiasis on Zanzibar: application of two novel assays for the detection of excreted albumin and haemoglobin in urine

As part of a urinary schistosomiasis control programme on Zanzibar, an aged cross-sectional survey of 305 children from three schools on Unguja was conducted to investigate the relationships between levels of excreted albumin and haemoglobin in urine and Schistosoma haematobium infection status. Diagnosis was determined by standard parasitological methods, dipstick reagents for microhaematuria, visual inspection for macrohaematuria as well as collection of case-history questionnaire data for self-diagnosis. Prevalence of infection as determined by parasitology was 53.9% and approximately, one quarter of the children examined were anaemic (<11 g dl(-1)). A statistically significant negative association of blood haemoglobin levels of boys and S. haematobium infection intensity status was observed (rs=-0.23, P=0.005). Through sensitivity analysis of urine-albumin values it was determined that a concentration of above >40 mg l(-1), as measured with the HemoCue urine-albumin photometer, had sensitivity, specificity, positive and negative predictive values of 0.90, 0.83, 0.86 and 0.89 respectively against 'gold-standard' parasitology. There was a clear association of reported pain upon micturition for children with elevated urine-albumin levels, with an odds ratio of 20 to 1. Levels of excreted blood in urine were quantified with the HemoCue Plasma/Low Hb photometer. However, dipsticks remain the method of choice for urine-haemoglobin of 0.1 g l(-1) and below. Urine parameters over a 24-h period were assessed in a small sub-sample. Reductions in both albumin and haemoglobin excretion were observed in 11 children 54 days after praziquantel treatment. It was concluded that these rapid, high-through-put, portable HemoCue assays could play a role in better describing and monitoring the occurrence, severity and evolution of urinary schistosomiasis disease. The urine-albumin assay has particular promise as a biochemical marker of S. haematobium induced kidney- and upper urinary tract-morbidity.

Thomas H Weller, Growing pathogens in tissue cultures: fifty years in academic tropical medicine, pediatrics, and virology, Science History Publications for Boston Medical Library, 2004, pp. xi, 291 (hardback 0-88135-380-9).

Thomas H Weller, Growing pathogens in tissue cultures: fifty years in academic tropical medicine, pediatrics, and virology, Science History Publications for Boston Medical Library, 2004, pp. xi, 291 (hardback 0-88135-380-9).

Structure of the cytosolic Cu,Zn superoxide dismutase from Schistosoma mansoni.

Cu,Zn superoxide dismutase (Cu,Zn SOD) is an essential enzyme for protecting cells from the toxic effects of reactive oxygen species. In humans, two distinct Cu,Zn SOD genes are located on chromosomes 4 and 21 and mutations in the latter have been associated with familial amyotrophic lateral sclerosis. Similarly, schistosomes (trematode parasites responsible for the chronically debilitating disease schistosomiasis) also produce two distinct Cu,Zn SODs, in this case one cytosolic and one bearing a signal peptide. The crystal structure of the cytosolic form of the enzyme from the human trematode Schistosoma mansoni (SmCtSOD) was solved and refined to a resolution of 2.2 A (space group P2(1)2(1)2(1), R = 17.6% and R(free) = 24.1%) and 1.55 A (space group P2(1), R = 15.7% and R(free) = 17.1%). This is the first report of a crystal structure of a Cu,Zn superoxide dismutase derived from a human parasite. Alternate positions for the catalytic copper and its water ligand were refined for the 1.55 A SmCtSOD model, but the most interesting structural differences between SmCtSOD and the human homologue reside in the loops used for electrostatic guidance of the substrate to the enzyme active site.

The phylogeny of the Schistosomatidae based on three genes with emphasis on the interrelationships of Schistosoma Weinland, 1858.

Schistosomes are digenean flukes, parasitic of birds, mammals and crocodiles. The family Schistosomatidae contains species of considerable medical and veterinary importance, which cause the disease schistosomiasis. Previous studies, both morphological and molecular, which have provided a good deal of information on the phylogenetics of this group, have been limited in the number of species investigated or the type or extent of molecular data used. This paper presents the most comprehensive phylogeny to date, based on the sequences of 3 genes, complete ribosomal small subunit rRNA and large ribosomal subunit rRNA, and mitochondrial cytochrome oxidase 1, sequenced from 30 taxa including at least 1 representative from 10 of the 13 known genera of the Schistosomatidae and 17 of the 20 recognized Schistosoma species. The phylogeny is examined using morphological characters, intermediate and definitive host associations and biogeography. Theories as to the origins and spread of Schistosoma are also explored. The principal findings are that Ornithobilharzia and Austrobilharzia form a sister group to the Schistosoma; mammalian schistosomes appear paraphyletic and 2 Trichobilharzia species, T. ocellata and T. szidati, seem to be synonymous. The position of Orientobilharzia within the Schistosoma is confirmed, as is an Asian origin for the Schistosoma, followed by subsequent dispersal through India and Africa.

Serum hyaluronic acid as a comprehensive marker to assess severity of liver disease in schistosomiasis

Schistosomiasis mansoni is a non-cirrhotic fibrogenic disease model. The mild form shows normal liver function with slight or no liver fibrosis whereas in the periportal fibrosis form the manifestations of portal hypertension prevail over hepatocellular failure. We assessed serum hyaluronic acid as a marker of the course of the disease. We studied 24 patients presenting with pure chronic forms of schistosomiasis and seven with cirrhosis. In order to measure serum hyaluronic acid we developed a sandwich fluorescent ELISA-like assay. α2-Macroglobulin, prothrombin index, γ-glutamyltransferase, platelets and ultrasound parameters were also assessed. The 20 μg/l (ROC plot) hyaluronic acid level differentiated patients with the mild form (with no portal hypertension) from those with the severe form of schistosomiasis with 78% diagnostic efficacy. The 80 μg/l cut-off value differentiated patients with the severe form of schistosomiasis from the cirrhotic group with similar diagnostic efficacy. α2-Macroglobulin provided no distinction between the groups studied. The hyaluronic acid serum concentration correlated positively with the splenic vein diameter ( P=0.004) and marginally with α2-macroglobulin ( P=0.059). Serum hyaluronic acid is a good marker for the initial phase of hepatic fibrosis and it was able to assess severity of liver disease in schistosomiasis.

Estimating the burden of disease from water, sanitation, and hygiene at a global level.

We estimated the disease burden from water, sanitation, and hygiene at the global level taking into account various disease outcomes, principally diarrheal diseases. The disability-adjusted life year (DALY) combines the burden from death and disability in a single index and permits the comparison of the burden from water, sanitation, and hygiene with the burden from other risk factors or diseases. We divided the world's population into typical exposure scenarios for 14 geographical regions. We then matched these scenarios with relative risk information obtained mainly from intervention studies. We estimated the disease burden from water, sanitation, and hygiene to be 4.0% of all deaths and 5.7% of the total disease burden (in DALYs) occurring worldwide, taking into account diarrheal diseases, schistosomiasis, trachoma, ascariasis, trichuriasis, and hookworm disease. Because we based these estimates mainly on intervention studies, this burden is largely preventable. Other water- and sanitation-related diseases remain to be evaluated. This preliminary estimation of the global disease burden caused by water, sanitation, and hygiene provides a basic model that could be further refined for national or regional assessments. This significant and avoidable burden suggests that it should be a priority for public health policy.

Mummies and molecules: Molecular biology meets paleopathology

Paleopathology, the study of disease in antiquity, has traditionally relied on artistic representations, ancient texts, and the gross and microscopic analysis of human remains to provide information about ancient disease. These sources, however, can be vague and difficult to interpret. In the last decade, paleopathologists have begun to incorporate modern laboratory methods into their research with intriguing results. DNA analysis and immunochemical techniques have enabled definitive diagnosis and prevalent studies of infectious diseases in both mummified and skeletal remains, some as much as 4,000 years old. Tuberculosis, schistosomiasis, leprosy, malaria, and Chagas' disease have all been the subject of successful studies. This research has contributed to our knowledge of the natural history of disease and has opened the door to such potential new fields as paleogenetics, paleovirology, and paleoepidemiology. The use of laboratory techniques in paleopathology allows researchers to test their traditional methods and provides access to health information previously available only for living populations. Though limited somewhat by problems of contamination and molecular degradation, the results of research conducted thus far suggest a bright future for modern laboratory methods and the study of ancient health and disease.

Vaccines for parasitic diseases.

Significant effort and progress has occurred over the last several years in the development of vaccines against three main tropical parasitic diseases (malaria, leishmaniases and schistosomiasis). However, an effective vaccine is not yet available. The difficulties in developing a vaccine against parasitic disease are complicated not only by the necessity to identify (and produce) appropriate, protective antigens but also a lack of complete understanding of the types of immune responses needed for protection. Despite these hurdles, several candidate vaccines are under development for each disease; at least one promising vaccine candidate exists that is in late stage clinical testing.

Peptide-based Synthetic Recombinant Vaccines with Anti-viral Efficacy

Synthetic recombinant vaccines are constructs in which a synthetic oligonucleotide coding for a protective epitope is inserted into an adequate gene for expression of the epitope. We report the results obtained using recombinant flagella of Salmonella vaccine strain expressing epitopes of influenza virus or of the parasiteSchistosoma mansoni . In the case of influenza virus, three conserved epitopes of the haemagglutinin and the nucleoprotein of the virus inducing B- and T-cell immune response, were expressed and the flagella were used for intranasal immunization without any adjuvant. Both humoral and cellular immune responses specific to the virus induced in mice cross-strain long-term protection against challenge infection. Aged mice were also able to resist infection. For the design of a human influenza vaccine, epitopes recognized by the HLAs prevalent in Caucasian populations were used, and the resulting vaccine was evaluated in human/mouse radiation chimaera in which human PBMC are functionally engrafted. The vaccinated mice demonstrated efficient clearance of the virus after challenge and resistance to lethal infection. In the case of the parasitic disease schistosomiasis, a 14-residue peptide denoted 9B peptide 1 was expressed in the flagella. Intranasal vaccination of mice with this construct, without the use of adjuvant, resulted in 40% protection against challenge infection.

Taking a long clear view of the enemy.

The Imaging of Tropical Diseasesedited by Philip E.S. Palmer and Maurice M. Reeder. Springer-Verlag, 2001. (hbk, 2 Vols) £344(Vol. 1, xi + 879 pages) ISBN 3-540 56028 9(Vol. 2, xi + 895 pages) ISBN 3 540 6247 6One of the most spectacular developments in medical diagnosis in recent years has been the growth of novel methods for imaging the human body. Computer-assisted tomography, magnetic resonance (MR) imaging and ultrasonography are now well established in many medical centres, and various other refinements and applications of biophysical principles are being steadily added to the list. The extraordinarily detailed views of the interior of the living body provided by these techniques are transforming clinical investigations, although one must remember the more important revolution that occurred over 100 years ago, when Roentgen introduced X-radiology as a diagnostic tool.Tropical medicine has benefited much from radiology, although, of course, has often been severely hampered by poverty of equipment and trained operators. This book is the second edition of a monument to those who have laboured long and hard to chart the radiological changes caused by a wide range of parasitic diseases, bacterial and fungal infections, tumours, cardiovascular diseases and other conditions that are common in tropical regions. Published in two volumes, Palmer and Reeder have assembled an impressive team of contributors from radiological centres worldwide, systematically providing radiological images of various kinds for each disease, enriched by brief accounts of their history, pathobiology, epidemiology, clinical manifestations and current treatment. Some chapters could be books in their own right; for example, those on amoebiasis, schistosomiasis and hydatid disease are each over 100 pages long, all have impressive sets of illustrations drawn from conventional and recent imaging techniques and all contain valuable bibliographies. There is a chapter devoted entirely to ultrasonographic images and another on how to set up and run a field X-ray unit, an interesting touch that emphasizes the practical nature of the book. Although there are inevitable variations in the quality of the older images, and the photographs of gross and microscopic pathology would have benefitted from colour, on the whole, the illustrations are excellent.Although the book is clearly aimed at practicing radiologists, the breadth and depth of information is fascinating, and there is much for the parasitologist to ponder; for example, the variety of sites affected in the body, and the extent to which life can be sustained in gross, untreated chronic infections, such as those seen in MR images of advanced cranial hydatid cysts. Dipping into various chapters, the reader is also rewarded with fascinating snippets of information, such as arthropodal infections of the nose and throat, picked up from contact with snakes, where larvae of the tongue worm, Pentastoma, disport themselves in the respiratory tract. There is also the message that many tropical diseases are poorly understood and new ones will probably be discovered. For example, in 1963, the cause of an outbreak of gastroenteritis in the Philippines was found to be a previously unknown nematode, Capillaria phillipinensis. Another example is the intriguing disease in West Africa called ainhum (of unknown cause), which involves spontaneous auto-amputation of toes.In conclusion, this is an impressive book that will be of much value and interest to radiologists and others concerned with tropical disease, a discipline that is likely to expand as global warming and movements of populations progress. As expected of its publisher, Springer-Verlag, the volumes are beautifully produced, and will grace the shelves of those lucky enough to be able to afford them. The wealth of images also reflects the tremendous impact of infectious diseases on human populations, and the reader is again reminded that: in much of our world, infectious agents of many kinds are responsible for widespread suffering and death; medical help is mostly scarce and effective treatment is scarcer; and many of these diseases are easily preventable, given appropriate socio-economic and political conditions, whereas others require vigorous pharmaceutical research and development just to contain them. These are uncomfortable thoughts and make one ponder our priorities as we plan for the coming high-tech postgenomic era.

Glomerular Detection of Schistosomal Antigen by Immunoelectron Microscopy in Human Mansonian Schistosomiasis

Schistosomal antigens (S. mansoni) were detected in glomeruli of nine patients with nephropathy and nephrotic syndrome by immunoelectron microscopy. The criteria for patients' selection were presence of intestinal schistosomiasis and absence of any surgical or other medical diseases, particularly lupus erythematosus, syphilis, and hepatitis B and C, which could explain the renal disease. When examined by light microscopy, kidney biopsies showed type I membranoproliferative glomerulonephritis in four patients, focal segmental glomerulosclerosis in two, and mesangioproliferative glomerulonephritis, membranous glomerulonephritis, and minimal change disease in one each of the remaining three patients. Immunofluorescence showed mainly immunoglobulin G (IgG), IgM, and different complement components (C3, Clq) deposits, particularly in the mesangial area, in eight patients. All patients had gold-labeled schistosomal antigen deposits in their glomeruli, chiefly in mesangial cells and matrix, along the glomerular membrane, and occasionally in the cytoplasm of epithelial cells. Although membranous glomerulonephritis has been rarely described in association with schistosomiasis and minimal change disease may be occasionally caused by an infectious disease like syphilis, the absence of definite experimental models and epidemiologic data suggests that coincidental pathologies without causal relationship with schistosomiasis cannot be ruled out to explain these findings.

Cytokine production in acute versus chronic human Schistosomiasis mansoni: the cross-regulatory role of interferon-gamma and interleukin-10 in the responses of peripheral blood mononuclear cells and splenocytes to parasite antigens.

The contribution of interleukin (IL)-10 and interferon (IFN)-gamma to the regulation of type 1 and type 2 cytokine responses was investigated in Brazilians with different clinical forms of schistosomiasis mansoni. Cells from members of a family with acute intestinal schistosomiasis responded to schistosomal soluble egg antigen (SEA) or soluble adult worm antigen preparation (SWAP) with greater amounts of IFN-gamma than did cells from several patients with chronic intestinal schistosomiasis; IL-10 levels were similar. Neutralization of IL-10 had no effect on the SEA-specific IFN-gamma response in patients with acute infection, whereas SWAP-induced IFN-gamma was increased in both groups. Anti-IL-10 also up-regulated SEA-specific IFN-gamma protein and mRNA responses in most splenocyte cultures from hepatosplenic schistosomiasis patients but had no effect on antigen-specific IL-4 or IL-5 production. Neutralization of IFN-gamma resulted in a comparable increase in SWAP-specific IL-10 and IL-5, while IL-4 was not affected. These studies demonstrate that early disease in schistosomiasis is associated with a significant IFN-gamma response and that IL-10 contributes to the suppression of that response during both early and chronic infection.

Bore holes and the vanishing of guinea worm disease in Ghana's Upper Region

Ghana's Upper Region provides an excellent example of the beneficial effects of improved water security provided by hand-pump tube wells. Following a Ghana-Canada bilateral development project that installed some 2500 pumps, protection rates against guinea worm disease may be estimated as 88% in the west, and 96% in the east. Survey comparisons between ca 1960 and 1990 show that dracunculiasis declined in 32 of a total of 38 areas. The shadow of guinea worm has been lifted from the land and, in many areas, a true “vanishing” has occurred. The few areas of disease increase are characterized by the lowest population densities, pioneer settlement for cotton farming, and an absence of bore holes. Vagaries of development have inadvertently produced disease transformations or “metamorphoses” from dracunculiasis to elephantiasis (lymphatic filariasis) in one area, and to red water disease ( schistosomiasis hematobium) in other areas. Correlative associations between pump densities and guinea worm disease are weakened by the large size of areas for which disease is reported in 1990. One preliminary finding is that geographical distance to the pump is a stronger influence than demographic pressure on pumps, regarding dracunculiasis. Diminishing returns on higher pump densities in many areas support the idea of making fuller, safer use of supplementary non-pump water. Despite crises of fee payment and pump maintenance, the rural bore hole project has struck a mortal blow against guinea worm, and permanently raised the quality of life in the Upper Region.

Dynamic modeling of epidemiologic patterns of schistosomiasis morbidity.

This paper uses preliminary mathematical models to examine how the dynamic relationship between schistosomiasis infection and disease is altered by chemotherapy. Two types of morbidity are examined: an acute form that is proportional to current infection intensity and that resolves after treatment, and a chronic form that represents accumulated experience of infection and that does not resolve after treatment, or resolves according to some delay function. The analyses indicate that nonlinearities in the age and frequency distributions of infection intensity have a marked impact on the patterns of morbidity. They also suggest that treatment close to the age of maximum infection intensity (i.e., children of schoolage) is most effective in controlling morbidity in the community as a whole. These models are preliminary, and their further development to include more realistic assumptions in relation to field data is discussed.

Genetic localization of a locus controlling the intensity of infection by Schistosoma mansoni on chromosome 5q31-q33.

Three hundred million individuals are at risk of infection by schistosomes and around 200,000 die each year of this disease. Severe clinical disease in schistosomiasis is often the consequence of heavy infection which, in several endemic areas, are determined largely by the susceptibility/resistance of individuals. Previously, we reported evidence, based on a segregation analysis in Brazilian pedigrees, that intensity of infection by Schistosoma mansoni was influenced by a major gene, indicating that host genetic factors are probably critical in controlling schistosome infection and disease development. To localize this gene, referred to as SM1, we performed a genome-wide study on 142 Brazilian subjects belonging to 11 informative families Our results show a linkage to only one region, on chromosome 5q31-q33, with maximum two-point lod scores of +4.74 and +4.52 for D5S636 and the colony stimulating factor-1 receptor marker (CSF1R), respectively. This was corroborated by multipoint analysis, indicating a close proximity to CSF1R as the most likely location of SM1. This region contains several candidate genes encoding immunological molecules that were shown to play important roles in human protection against schistosomes.

Investigations of molluscicidal saponins from the Endod plant Phytolacca dodecandra.

The parasitic disease schistosomiasis is a major health problem in many tropical countries and over 300 million people are infected. Freshwater snails act as intermediate hosts for the parasite and because of that, the infection is transmitted among humans on water contact, mainly in rural areas with minimal domestic water supply and poor sanitary facilities. It has been realized that eradication of the disease is impossible with the available resources and therefore the immediate aim is control of morbidity. Despite the success of some control programs, the prevalence of schistosomiasis remains constant, largely because population growth and development of man-made water resources is continuing (WHO, 1993). Treatment of water bodies with molluscicidal compounds, in order to reduce the number of transmitting snails, is considered an important element in integrated strategies for morbidity control. However, large scale use of synthetic molluscicides are impeded by the high costs and thus there is a demand for inexpensive alternatives (Mott, 1987). The interest in studying plant material containing molluscicidal compounds is based on the idea of producing a local supply of molluscicides in the endemic areas at low cost and by simple technologies.KeywordsOleanolic AcidAnomeric ProtonSaponin ContentCarbohydrate ResidueSchistosomiasis ControlThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.