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Host determinants of reinfection with schistosomes in humans: a systematic review and meta-analysis.PLoS Neglected Tropical Diseases Sep 2014Schistosomiasis is still a major public health burden in the tropics and subtropics. Although there is an effective chemotherapy (Praziquantel) for this disease,... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Schistosomiasis is still a major public health burden in the tropics and subtropics. Although there is an effective chemotherapy (Praziquantel) for this disease, reinfection occurs rapidly after mass drug administration (MDA). Because the entire population do not get reinfected at the same rate, it is possible that host factors may play a dominant role in determining resistance or susceptibility to reinfection with schistosomes. Here, we systematically reviewed and meta-analyzed studies that reported associations between reinfection with the principal human-infecting species (S. mansoni, S. japonicum and S. haematobium) and host socio-demographic, epidemiological, immunological and genetic factors.
METHODOLOGY/PRINCIPAL FINDINGS
PubMed, Scopus, Google Scholar, Cochrane Review Library and African Journals Online public databases were searched in October 2013 to retrieve studies assessing association of host factors with reinfection with schistosomes. Meta-analysis was performed to generate pooled odds ratios and standardized mean differences as overall effect estimates for dichotomous and continuous variables, respectively. Quality assessment of included studies, heterogeneity between studies and publication bias were also assessed. Out of the initial 2739 records, 109 studies were included in the analyses, of which only 32 studies with 37 data sets were eligible for quantitative data synthesis. Among several host factors identified, strong positive association was found with age and pre-treatment intensity, and only slightly for gender. These factors are major determinants of exposure and disease transmission. Significant positive association was found with anti-SWA IgG4 level, and a negative overall effect for association with IgE levels. This reconfirmed the concept that IgE/IgG4 balance is a major determinant of protective immunity against schistosomiasis. Other identified determinants were reported by a small number of studies to enable interpretation.
CONCLUSIONS
Our data contribute to the understanding of host-parasite interaction as it affects reinfection, and is a potential tool to guide planning and tailoring of community interventions to target high-risk groups.
Topics: Animals; Disease Susceptibility; Host-Parasite Interactions; Humans; Recurrence; Schistosoma; Schistosomiasis
PubMed: 25211227
DOI: 10.1371/journal.pntd.0003164 -
Parasitology International Apr 2013Schistosomiasis japonica continues to be an important zoonotic disease in the People's Republic of China (P.R. China), despite decades of dedicated control efforts.... (Meta-Analysis)
Meta-Analysis Review
Schistosomiasis japonica continues to be an important zoonotic disease in the People's Republic of China (P.R. China), despite decades of dedicated control efforts. Different interventions for its control including chemotherapy of humans and animals, mollusciciding, environmental modification, and health education have been implemented at various stages of the control efforts and in different combinations, resulting in remarkable achievements. Here, we present a systematic review and meta-analysis of the documented effectiveness of health education to reduce schistosomiasis japonica transmission in P.R. China. A total of 10 relevant publications were identified and included in the meta-analysis. The reported results indicate that the prevalence of Schistosoma japonicum infection in humans and schistosomiasis-related knowledge are significantly influenced by health education. The implementation of health education over more than 2 years was associated with an overall schistosomiasis japonica prevalence decrease of 6% (95% CI: 2%, 11%) and an overall increase of 51% (95% CI: 41%, 61%) in schistosomiasis-related knowledge after controlling for confounding factors. Among control groups, the prevalence of schistosomiasis japonica and relevant knowledge levels were not significantly influenced. The relative risk (RR) of an infection with S. japonicum following health education lasting more than 2 years was 0.43 (95% CI: 0.24, 0.78). In summary, a considerable effectiveness of health education with regard to preventing S. japonicum infections in P.R. China and increasing relevant knowledge is documented in the extant literature. This suggests that the effectiveness of health education may be considerable, particularly after its long-term implementation.
Topics: Animals; China; Health Education; Health Knowledge, Attitudes, Practice; Humans; Prevalence; Risk; Schistosoma japonicum; Schistosomiasis japonica; Zoonoses
PubMed: 23201566
DOI: 10.1016/j.parint.2012.11.006 -
PloS One 2012Chemotherapy based on repeated doses of praziquantel is still the most effective control strategy against Schistosomiasis, however artemisinin derivatives emerged as a... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Chemotherapy based on repeated doses of praziquantel is still the most effective control strategy against Schistosomiasis, however artemisinin derivatives emerged as a family of compounds with schistomicide activity. The aim of the present work is to compare the efficacy of artemisinin-based therapies in the treatment and prophylaxis of human schistosomiasis. The design of this work involved a quantitative systematic review and meta-analysis.
METHODOLOGY/PRINCIPAL FINDINGS
Retrieval of published studies was carried out through an electronic search of the PubMed (MEDLINE), EMBASE, Cochrane Library and CINAHL databases. This included reports comparing the therapeutic efficacy of artesunate alone, artesunate plus sulfadoxine-pyrimethamine and a combination of artemisinin derivatives plus praziquantel against praziquantel alone on different types of schistosomiasis. Moreover, studies on artesunate and artemether used as preventive drugs were also analyzed against placebo. The primary outcome measure for schistosomiasis treatment was "parasitological cure", whereas for the prophylaxis the outcome evaluated was "infection rate". Our results show that patients treated with artesunate alone have significantly lower cure rates than those treated with praziquantel (OR = 0.27 (95% C.I. 0.13-0.53; p<0.001)) and that the combined therapy of artesunate plus sulfadoxine-pyrimethamine is also significantly less effective than praziquantel treatment (OR = 0.14 (95% C.I. 0.02-0.92; p = 0.04)). However, the combination of an artemisinin derivatives plus praziquantel showed a higher cure rate than praziquantel monotherapy with OR = 2.07 (95% C.I. 1.27-3.36; p = 0.003). Finally, chemoprophylaxis with either artesunate (RR = 0.11 (95% C.I. 0.06-0.22; p<0.001)) or artemether (RR = 0.25 (95% C.I. 0.16-0.40; p<0.001)) was significantly better than a placebo in both cases.
CONCLUSIONS/SIGNIFICANCE
This meta-analysis confirms that artemisinin derivatives used in combination with praziquantel have the potential to increase the cure rates in schistosomiasis treatment, but not artesunate alone. It is also confirmed that repeated doses of artemisinin derivatives play a prophylactic role, significantly reducing the incidence of Schistosoma japonicum infections compared with placebo.
Topics: Antiprotozoal Agents; Artemisinins; Clinical Trials as Topic; Drug Combinations; Drug Therapy, Combination; Humans; Praziquantel; Pyrimethamine; Schistosomiasis; Sulfadoxine; Treatment Outcome
PubMed: 23029285
DOI: 10.1371/journal.pone.0045867 -
Parasites & Vectors Oct 2011Praziquantel has been used as first-line drug for chemotherapy of schistosomiasis since 1984. Besides praziquantel, artemether and artesunate have also been used for the... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Praziquantel has been used as first-line drug for chemotherapy of schistosomiasis since 1984. Besides praziquantel, artemether and artesunate have also been used for the control of this infectious disease since late 1990s. In this article, we conducted a systematic review and meta-analysis to evaluate the antischistosomal efficacy of different medication strategies including monotherapy or combination therapies of these drugs.
RESULTS
A number of 52 trials from 38 articles published in peer-reviewed journals before July 2011 were selected for analysis after searching the following literature databases: the Cochrane Library, PubMed/Medline, ISI Web of Science, Chinese Biomedicine Literature Database, and China National Knowledge Infrastructure. Our meta-analyses showed that a dosage of 30-60 mg/kg praziquantel compared with placebo produced a protection rate of about 76% (95% CI: 67%-83%) for treating human schistosomiasis, which varied from 70% to 76% with no significant differences among the subspecies S. haematobium, S. japonicum or S. mansoni. Protection rates were higher when praziquantel doses were elevated, as concluded from the nRCTs results: the protection rate of praziquantel at 40 mg/kg was 52% (95% CI: 49%-55%), and it increased to 91% (95% CI: 88%-92%) when the dosages were elevated to 60/80/100 mg/kg divided two or more doses. Multiple doses of artemether or artesunate over 1- or 2-week intervals resulted in protection rates of 65% to 97% for preventing schistosomiasis, and increased doses and shorter medication intervals improved their efficacies. Praziquantel and artemisinin derivatives (artemether or artesunate) in combination resulted in a higher protection rate of 84% (95% CI: 64%-91%) than praziquantel monotherapy for treatment. praziquantel and artesunate in combination had a great protection rate of 96% (95% CI: 78%-99%) for preventing schistosomes infection.
CONCLUSIONS
According to the results, praziquantel remains effective in schistosomiasis treatment, and multiple doses would improve its efficacy; meanwhile, praziquantel is also a good drug for preventing acute schistosomiasis morbidity. It's better to use multiple doses of artemether or artesunate with 1- or 2-week intervals for prevention against schistosome infection. Praziquantel and artemether or artesunate in combination perform better in treatment than praziquantel monotherapy, and they are especially suitable for treating the patients with repeated exposure to infected water.
Topics: Animals; Artemisinins; Dose-Response Relationship, Drug; Humans; Praziquantel; Randomized Controlled Trials as Topic; Schistosoma; Schistosomiasis; Schistosomicides
PubMed: 22004571
DOI: 10.1186/1756-3305-4-201 -
Parasitology International Dec 2011Several human genetic variants, HLA antigens and alleles are reportedly linked to post-schistosomal hepatic disorder (PSHD), but the results from these reports are... (Meta-Analysis)
Meta-Analysis Review
Several human genetic variants, HLA antigens and alleles are reportedly linked to post-schistosomal hepatic disorder (PSHD), but the results from these reports are highly inconclusive. In order to estimate overall associations between human genetic variants, HLA antigens, HLA alleles and PSHD, we systematically reviewed and performed a meta-analysis of relevant studies in both post-schistosomal hepatic disorder and post-schistosomal non-hepatic disorder patients. PubMed, Scopus, Google Scholar, The HuGE Published Literature database, Cochrane Library, and manual search of reference lists of articles published before July 2009 were used to retrieve relevant studies. Two reviewers independently selected articles and extracted data on study characteristics and data regarding the association between genetic variants, HLA antigens, HLA alleles and PSHD in the form of 2×2 tables. A meta-analysis using fixed-effects or random-effects models to pooled odds ratios (OR) with corresponding 95% confidence intervals were calculated only if more than one study had investigated particular variation. We found 17 articles that met our eligibility criteria. Schistosoma mansoni and Schistosoma japonicum were reported as the species causing PSHD. Since human genetic variants were only investigated in one study, these markers were not assessed by meta-analysis. Thus, only HLA-genes (a total of 66 HLA markers) were conducted in the meta-analysis. Our meta-analysis showed that human leucocyte antigens HLA-DQB1*0201 (OR=2.64, P=0.018), DQB1*0303 (OR=1.93, P=0.008), and DRB1*0901 (OR=2.14, P=0.002) alleles and HLA-A1 (OR=5.10, P=0.001), A2 (OR=2.17, P=0.005), B5 (OR=4.63, P=0.001), B8 (OR=2.99, P=0.02), and B12 (OR=5.49, P=0.005) serotypes enhanced susceptibility to PSHD, whereas HLA-DQA1*0501 (OR=0.29, P≤0.001) and DQB1*0301 (OR=0.58, P=0.007) were protective factors against the disease. We further suggested that the DRB1*0901-DQB1*0201, DRB1*0901-DQB1*0303 and A1-B8 haplotypes enhanced susceptibility to PSHD, whereas DQA1*0501-DQB1*0301 linkage decreased the risk of PSHD. The result improved our understanding of the association between the HLA loci and PSHD with regard to pathogenic or protective T-cells and provided novel evidence that HLA alleles may influence disease severity.
Topics: Africa; Alleles; Animals; Asia; Databases, Bibliographic; Genetic Linkage; Genetic Predisposition to Disease; Genotype; Haplotypes; Histocompatibility Antigens Class I; Histocompatibility Antigens Class II; Humans; Liver Diseases; Odds Ratio; Schistosoma japonicum; Schistosoma mansoni; Schistosomiasis; Severity of Illness Index; South America
PubMed: 21664486
DOI: 10.1016/j.parint.2011.05.008 -
PLoS Neglected Tropical Diseases Mar 2008Schistosomiasis is among the most prevalent parasitic infections worldwide. However, current Global Burden of Disease (GBD) disability-adjusted life year estimates... (Review)
Review
Schistosomiasis is among the most prevalent parasitic infections worldwide. However, current Global Burden of Disease (GBD) disability-adjusted life year estimates indicate that its population-level impact is negligible. Recent studies suggest that GBD methodologies may significantly underestimate the burden of parasitic diseases, including schistosomiasis. Furthermore, strain-specific disability weights have not been established for schistosomiasis, and the magnitude of human disease burden due to Schistosoma japonicum remains controversial. We used a decision model to quantify an alternative disability weight estimate of the burden of human disease due to S. japonicum. We reviewed S. japonicum morbidity data, and constructed decision trees for all infected persons and two age-specific strata, <15 years (y) and > or =15 y. We conducted stochastic and probabilistic sensitivity analyses for each model. Infection with S. japonicum was associated with an average disability weight of 0.132, with age-specific disability weights of 0.098 (<15 y) and 0.186 (> or =15 y). Re-estimated disability weights were seven to 46 times greater than current GBD measures; no simulations produced disability weight estimates lower than 0.009. Nutritional morbidities had the greatest contribution to the S. japonicum disability weight in the <15 y model, whereas major organ pathologies were the most critical variables in the older age group. GBD disability weights for schistosomiasis urgently need to be revised, and species-specific disability weights should be established. Even a marginal increase in current estimates would result in a substantial rise in the estimated global burden of schistosomiasis, and have considerable implications for public health prioritization and resource allocation for schistosomiasis research, monitoring, and control.
Topics: Animals; Humans; Models, Theoretical; Quality-Adjusted Life Years; Schistosomiasis japonica
PubMed: 18320018
DOI: 10.1371/journal.pntd.0000158