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Lancet (London, England) Sep 2006Schistosomiasis or bilharzia is a tropical disease caused by worms of the genus Schistosoma. The transmission cycle requires contamination of surface water by excreta,... (Review)
Review
Schistosomiasis or bilharzia is a tropical disease caused by worms of the genus Schistosoma. The transmission cycle requires contamination of surface water by excreta, specific freshwater snails as intermediate hosts, and human water contact. The main disease-causing species are S haematobium, S mansoni, and S japonicum. According to WHO, 200 million people are infected worldwide, leading to the loss of 1.53 million disability-adjusted life years, although these figures need revision. Schistosomiasis is characterised by focal epidemiology and overdispersed population distribution, with higher infection rates in children than in adults. Complex immune mechanisms lead to the slow acquisition of immune resistance, though innate factors also play a part. Acute schistosomiasis, a feverish syndrome, is mostly seen in travellers after primary infection. Chronic schistosomal disease affects mainly individuals with long-standing infections in poor rural areas. Immunopathological reactions against schistosome eggs trapped in the tissues lead to inflammatory and obstructive disease in the urinary system (S haematobium) or intestinal disease, hepatosplenic inflammation, and liver fibrosis (S mansoni, S japonicum). The diagnostic standard is microscopic demonstration of eggs in the excreta. Praziquantel is the drug treatment of choice. Vaccines are not yet available. Great advances have been made in the control of the disease through population-based chemotherapy but these required political commitment and strong health systems.
Topics: Animals; Anthelmintics; Female; Humans; Male; Praziquantel; Schistosoma; Schistosomiasis
PubMed: 16997665
DOI: 10.1016/S0140-6736(06)69440-3 -
Trends in Parasitology Dec 2011Schistosoma genomes provide a comprehensive resource for identifying the molecular processes that shape parasite evolution and for discovering novel chemotherapeutic or... (Review)
Review
Schistosoma genomes provide a comprehensive resource for identifying the molecular processes that shape parasite evolution and for discovering novel chemotherapeutic or immunoprophylactic targets. Here, we demonstrate how intragenus and intergenus comparative genomics can be used to drive these investigations forward, illustrate the advantages and limitations of these approaches and review how post-genomic technologies offer complementary strategies for genome characterisation. Although sequencing and functional characterisation of other schistosome/platyhelminth genomes continues to expedite anthelmintic discovery, we contend that future priorities should equally focus on improving assembly quality, and chromosomal assignment, of existing schistosome/platyhelminth genomes.
Topics: Animals; Anthelmintics; Chromosomes; Genome, Helminth; Genomics; Humans; Schistosoma; Schistosomiasis
PubMed: 22024648
DOI: 10.1016/j.pt.2011.09.003 -
Parasite Immunology 2012Schistosome research has entered the genomic era with the publications reporting the Schistosoma mansoni and Schistosoma japonicum genomes. Schistosome genomics is... (Review)
Review
Schistosome research has entered the genomic era with the publications reporting the Schistosoma mansoni and Schistosoma japonicum genomes. Schistosome genomics is motivated by the need for new control tools. However, much can also be learned about the biology of Schistosoma, which is a tractable experimental model. In this article, we review the recent achievements in the field of schistosome research and discuss future perspectives on genomics and how it can be integrated in a usable format, on the genetic mapping and how it has improved the genome assembly and provided new research approaches, on how epigenetics provides interesting insights into the biology of the species and on new functional genomics tools that will contribute to the understanding of the function of genes, many of which are parasite- or taxon specific.
Topics: Animals; Chromosome Mapping; Epigenomics; Genome, Helminth; Genomics; Helminth Proteins; Humans; Schistosoma; Schistosomiasis
PubMed: 22145587
DOI: 10.1111/j.1365-3024.2011.01349.x -
Annual Review of Genomics and Human... 2009Schistosomiasis, caused mainly by Schistosoma japonicum, S. mansoni, and S. hematobium, remains one of the most prevalent and serious parasitic diseases worldwide. The... (Review)
Review
Schistosomiasis, caused mainly by Schistosoma japonicum, S. mansoni, and S. hematobium, remains one of the most prevalent and serious parasitic diseases worldwide. The blood flukes have a complex life cycle requiring adaptation for survival in fresh water as free-living forms and as parasites in snail intermediate and vertebrate definitive hosts. Functional genomics analyses, including transcriptomic and proteomic approaches, have been performed on schistosomes, in particular S. mansoni and S. japonicum, using powerful high-throughput methodologies. These investigations have not only chartered gene expression profiles across genders and developmental stages within mammalian and snail hosts, but have also characterized the features of the surface tegument, the eggshell and excretory-secretory proteomes of schistosomes. The integration of the genomic, transcriptomic, and proteomic information, together with genetic manipulation on individual genes, will provide a global insight into the molecular architecture of the biology, pathogenesis, and host-parasite interactions of the human blood flukes. Importantly, these functional genomics analyses lay a foundation on which to develop new antischistosome vaccines as well as drug targets and diagnostic markers for treatment and control of schistosomiasis.
Topics: Animals; Genome, Helminth; Genomics; Host-Parasite Interactions; Humans; Polymorphism, Genetic; Schistosoma; Schistosomiasis
PubMed: 19630560
DOI: 10.1146/annurev-genom-082908-150036 -
Medecine Tropicale : Revue Du Corps de... 1997Schistosoma intercalatum bilharziasis continues to raise numerous questions regarding pathogenicity and gravity. The parasite was identified recently and the last fully... (Review)
Review
Schistosoma intercalatum bilharziasis continues to raise numerous questions regarding pathogenicity and gravity. The parasite was identified recently and the last fully described outbreak occurred 10 years ago in the city of Bata, Equatorial Guinea. Geographically Schistosoma intercalatum biharziasis is limited to one part of the African continent but has shown a tendency to spread. Hybridization of Schistosoma intercalatum and Schistosoma haematobium has been observed. The main clinical manifestation of Schistosoma intercalatum is rectal bleeding. The endoscopic appearance of lesions is variable and non-specific ranging from granulomas or polyps to ulcerations. Complications include severe rectitis or genital involvement such as salpingitis with secondary sterility. Spontaneous abortion has also been reported. Association with salmonella and klebsiella infection has been confirmed and can lead to life-threatening situations. Few studies have been performed to assess the value of diagnostic tests. The sensitivity of stool smears and urinary sedimentation testing is 81.7% and 56.3% respectively using the two examinations as references for one another. The sensitivity of immunological tests is generally good but varies depending on the reference technique used. Specificity can be affected by cross-reaction with other schistosomas or trematodes and even with nematodes and hematozoons. Treatment with a single dose of Biltricide has proven to be effective. Prevention requires education of the population at risk and use of molluscacides. The control strategy must be adapted in function of the epidemiology of the disease, diagnostic data, cost and effectiveness of screening and treatment.
Topics: Abortion, Spontaneous; Africa South of the Sahara; Animals; Antiplatyhelmintic Agents; Female; Gastrointestinal Hemorrhage; Humans; Inbreeding; Population Surveillance; Praziquantel; Pregnancy; Rectum; Schistosoma; Schistosomiasis; Sensitivity and Specificity
PubMed: 9513158
DOI: No ID Found -
Progress in Clinical Parasitology 1991
Review
Topics: Animals; Disease Reservoirs; Disease Vectors; Host-Parasite Interactions; Humans; Schistosoma; Schistosomiasis; Snails
PubMed: 1893118
DOI: No ID Found -
PLoS Neglected Tropical Diseases Mar 2020Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may...
BACKGROUND
Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may benefit from specific and sensitive diagnostic methods to detect Schistosoma trematodes in aquatic environments. Here we report the development of novel environmental DNA (eDNA) qPCR assays for the presence of the human-infecting species Schistosoma mansoni, S. haematobium and S. japonicum.
METHODOLOGY/PRINCIPAL FINDINGS
We first tested the specificity of the assays across the three species using genomic DNA preparations which showed successful amplification of target sequences with no cross amplification between the three focal species. In addition, we evaluated the specificity of the assays using synthetic DNA of multiple Schistosoma species, and demonstrated a high overall specificity; however, S. japonicum and S. haematobium assays showed cross-species amplification with very closely-related species. We next tested the effectiveness of the S. mansoni assay using eDNA samples from aquaria containing infected host gastropods, with the target species revealed as present in all infected aquaria. Finally, we evaluated the effectiveness of the S. mansoni and S. haematobium assays using eDNA samples from eight discrete natural freshwater sites in Tanzania, and demonstrated strong correspondence between infection status established using eDNA and conventional assays of parasite prevalence in host snails.
CONCLUSIONS/SIGNIFICANCE
Collectively, our results suggest that eDNA monitoring is able to detect schistosomes in freshwater bodies, but refinement of the field sampling, storage and assay methods are likely to optimise its performance. We anticipate that environmental DNA-based approaches will help to inform epidemiological studies and contribute to efforts to control and eliminate schistosomiasis in endemic areas.
Topics: Animals; DNA, Environmental; DNA, Helminth; Environmental Monitoring; Fresh Water; Genes, Helminth; Nucleic Acid Amplification Techniques; Phylogeny; Real-Time Polymerase Chain Reaction; Schistosoma; Schistosoma haematobium; Schistosoma japonicum; Schistosoma mansoni; Schistosomiasis; Schistosomiasis mansoni; Snails; Species Specificity; Tanzania
PubMed: 32203507
DOI: 10.1371/journal.pntd.0008129 -
Anais Da Academia Brasileira de Ciencias Jun 2011
Topics: Animals; Congresses as Topic; Schistosoma mansoni
PubMed: 21670866
DOI: 10.1590/s0001-37652011000200001 -
Disease Markers 2020Schistosomiasis is considered a neglected parasitic disease. Around 280,000 people die from it annually, and more than 779 million people are at risk of getting...
Schistosomiasis is considered a neglected parasitic disease. Around 280,000 people die from it annually, and more than 779 million people are at risk of getting infected. The schistosome species which infect human beings are , , , , , and . This disease is also of veterinary significance; the most important species being since it causes the disease in around 160 million livestock in Africa and Asia. This work was aimed at designing and developing a genus-specific loop-mediated isothermal amplification (LAMP) method for detecting the most important schistosome species affecting humans and for the species-specific detection of . Bioinformatics tools were used for primer design, and the LAMP method was standardised for detecting the ITS-1 region from , , , , and DNA (generic test) and the NADH 1 gene for specifically detecting (at different DNA concentrations). Detection limits achieved were 1 pg DNA for , 0.1 pg for , 1 pg for , and 10 pg for . No amplification for DNA was obtained. The LAMP designed for the amplification of NADH-1 worked specifically for this species, and no other DNA from other schistosome species included in the study was amplified. Two highly sensitive LAMP methods for detecting different species important for human and veterinary health were standardised. These methods could be very useful for the diagnosis and surveillance of schistosome infections.
Topics: Animals; Computational Biology; DNA, Protozoan; Early Diagnosis; Humans; Limit of Detection; Molecular Diagnostic Techniques; Nucleic Acid Amplification Techniques; Schistosoma; Schistosomiasis; Species Specificity
PubMed: 32774514
DOI: 10.1155/2020/8042705 -
PLoS Neglected Tropical Diseases Feb 2017Since 1984, WHO has endorsed drug treatment to reduce Schistosoma infection and its consequent morbidity. Cross-sectional studies suggest pre-treatment correlation... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Since 1984, WHO has endorsed drug treatment to reduce Schistosoma infection and its consequent morbidity. Cross-sectional studies suggest pre-treatment correlation between infection intensity and risk for Schistosoma-related pathology. However, evidence also suggests that post-treatment reduction in intensity may not reverse morbidity because some morbidities occur at all levels of infection, and some reflect permanent tissue damage. The aim of this project was to systematically review evidence on drug-based control of schistosomiasis and to develop a quantitative estimate of the impact of post-treatment reductions in infection intensity on prevalence of infection-associated morbidity.
METHODOLOGY/PRINCIPAL FINDINGS
This review was registered at inception with PROSPERO (CRD42015026080). Studies that evaluated morbidity before and after treatment were identified by online searches and searches of private archives. Post-treatment odds ratios or standardized mean differences were calculated for each outcome, and these were correlated to treatment-related egg count reduction ratios (ERRs) by meta-regression. A greater ERR correlated with greater reduction in odds of most morbidities. Random effects meta-analysis was used to derive summary estimates: after treatment of S. mansoni and S. japonicum, left-sided hepatomegaly was reduced by 54%, right-sided hepatomegaly by 47%, splenomegaly by 37%, periportal fibrosis by 52%, diarrhea by 53%, and blood in stools by 75%. For S. haematobium, hematuria was reduced by 92%, proteinuria by 90%, bladder lesions by 86%, and upper urinary tract lesions by 72%. There were no consistent changes in portal dilation or hemoglobin levels. In sub-group analysis, age, infection status, region, parasite species, and interval to follow-up were associated with meaningful differences in outcome.
CONCLUSION/SIGNIFICANCE
While there are challenges to implementing therapy for schistosomiasis, and praziquantel therapy is not fully curative, reductions in egg output are significantly correlated with decreased morbidity and can be used to project diminution in disease burden when contemplating more aggressive strategies to minimize infection intensity.
Topics: Animals; Anthelmintics; Humans; Praziquantel; Schistosoma; Schistosomiasis
PubMed: 28212414
DOI: 10.1371/journal.pntd.0005372