Effect of preventive chemotherapy with praziquantel on schistosomiasis among school-aged children in sub-Saharan Africa: a spatiotemporal modelling study.

BACKGROUND: Over the past 20 years, schistosomiasis control has been scaled up. Preventive chemotherapy with praziquantel is the main intervention. We aimed to assess the effect of preventive chemotherapy on schistosomiasis prevalence in sub-Saharan Africa, comparing 2000-10 with 2011-14 and 2015-19. METHODS: In this spatiotemporal modelling study, we analysed survey data from school-aged children (aged 5-14 years) in 44 countries across sub-Saharan Africa. The data were extracted from the Global Neglected Tropical Diseases database and augmented by 2018 and 2019 survey data obtained from disease control programmes. Bayesian geostatistical models were fitted to Schistosoma haematobium and Schistosoma mansoni survey data. The models included data on climatic predictors obtained from satellites and other open-source environmental databases and socioeconomic predictors obtained from various household surveys. Temporal changes in Schistosoma species prevalence were estimated by a categorical variable with values corresponding to the three time periods (2000-10, 2011-14, and 2015-19) during which preventive chemotherapy interventions were scaled up. FINDINGS: We identified 781 references with relevant geolocated schistosomiasis survey data for 2000-19. There were 19 166 unique survey locations for S haematobium and 23 861 for S mansoni, of which 77% (14 757 locations for S haematobium and 18 372 locations for S mansoni) corresponded to 2011-19. Schistosomiasis prevalence among school-aged children in sub-Saharan Africa decreased from 23·0% (95% Bayesian credible interval 22·1-24·1) in 2000-10 to 9·6% (9·1-10·2) in 2015-19, an overall reduction of 58·3%. The reduction of S haematobium was 67·9% (64·6-71·1) and that of S mansoni 53·6% (45·2-58·3) when comparing 2000-10 with 2015-19. INTERPRETATION: Our model-based estimates suggest that schistosomiasis prevalence in sub-Saharan Africa has decreased considerably, most likely explained by the scale-up of preventive chemotherapy. There is a need to consolidate gains in the control of schistosomiasis by means of preventive chemotherapy, coupled with other interventions to interrupt disease transmission. FUNDING: European Research Council and WHO.

Evaluation of a Urine Pooling Strategy for the Rapid and Cost-Efficient Prevalence Classification of Schistosomiasis.

BACKGROUND: A key epidemiologic feature of schistosomiasis is its focal distribution, which has important implications for the spatial targeting of preventive chemotherapy programs. We evaluated the diagnostic accuracy of a urine pooling strategy using a point-of-care circulating cathodic antigen (POC-CCA) cassette test for detection of Schistosoma mansoni, and employed simulation modeling to test the classification accuracy and efficiency of this strategy in determining where preventive chemotherapy is needed in low-endemicity settings. METHODOLOGY: We performed a cross-sectional study involving 114 children aged 6-15 years in six neighborhoods in Azaguié Ahoua, south Côte d'Ivoire to characterize the sensitivity and specificity of the POC-CCA cassette test with urine samples that were tested individually and in pools of 4, 8, and 12. We used a Bayesian latent class model to estimate test characteristics for individual POC-CCA and quadruplicate Kato-Katz thick smears on stool samples. We then developed a microsimulation model and used lot quality assurance sampling to test the performance, number of tests, and total cost per school for each pooled testing strategy to predict the binary need for school-based preventive chemotherapy using a 10% prevalence threshold for treatment. PRINCIPAL FINDINGS: The sensitivity of the urine pooling strategy for S. mansoni diagnosis using pool sizes of 4, 8, and 12 was 85.9%, 79.5%, and 65.4%, respectively, when POC-CCA trace results were considered positive, and 61.5%, 47.4%, and 30.8% when POC-CCA trace results were considered negative. The modeled specificity ranged from 94.0-97.7% for the urine pooling strategies (when POC-CCA trace results were considered negative). The urine pooling strategy, regardless of the pool size, gave comparable and often superior classification performance to stool microscopy for the same number of tests. The urine pooling strategy with a pool size of 4 reduced the number of tests and total cost compared to classical stool microscopy. CONCLUSIONS/SIGNIFICANCE: This study introduces a method for rapid and efficient S. mansoni prevalence estimation through examining pooled urine samples with POC-CCA as an alternative to widely used stool microscopy.

[Recommendation of a new clinical classification of advanced schistosomiasis].

OBJECTIVE: To recommend a new clinical classification of advanced schistosomiasis for improving the diagnosis and evaluation of therapeutic effect of advanced schistosomiasis. METHODS: The medical records of 11 092 cases of advanced schistosomiasis from the Xiang-Yue Hospital from January 1990 to January 2010 and the medical aid centre for advance schistosomiasis in Hunan Province from January 2004 to January 2010 were collected and classified with the current and new clinical classification methods and the results were statistically analyzed and compared. RESULTS: Based on the current classification method, there were huge splenomegaly (5 710 cases), ascites (2 993 cases), colon proliferative (834 cases), and dwarf (54 cases). However, 1 501 cases were excluded from the current classification. Based on the new classification method, there were 8 types: huge splenomegaly (2 870 cases), ascites (1 885 cases), colon proliferative (425 cases), dwarf (38 cases), universal (1 281 cases), bleeding (1 857 cases), hepatic coma (553 cases), and miscellaneous (1 759 cases). Totally 424 cases were classified into chronic schistosomiasis. CONCLUSION: The new classification method can present a more comprehensive picture for clinical features, severe complications and prognosis of advanced schistosomiasis, and is useful for the diagnosis and treatment of advanced schistosomiasis.

A prognostic index (bladder prognostic index) for bilharzial-related invasive bladder cancer.

PURPOSE: Bladder cancer is still the most common solid tumor among adult males in Egypt because of the prevalence of bilharzial infestation, especially in the countryside. In this prospective study, we have recorded the prognostic factors for 180 patients with invasive bladder cancer for whom standard radical cystectomy had been performed to develop a prognostic index (bladder prognostic index) that defines high risk patients who are more vulnerable to disease relapse after surgery and who may benefit from additional therapy. PATIENTS AND METHODS: The study was performed between January 1997 and December 1999, in which 180 patients with histopathologically proved invasive bladder cancer associated with bilharziasis underwent radical cystectomy or anterior pelvic exenteration. After surgery, patients were regularly followed for a minimum of 2 years. RESULTS: Our patients included 141 males and 39 females. Squamous cell carcinoma was the most common type (53.3%), and most of the tumors were grade II (61.1%). A total of 173 patients had their tumors operable, while 7 were inoperable. We had 5 (2.8%) operative related mortalities. At 5 years postoperatively, free and overall survival rates for the whole group of patients were 31.44%+/-5.9% and 32.5%+/-6.8%, respectively. Tumor pathologic stage, grade, and nodal affection were the only significant factors with impact on survival (P=0.008, 0.051, and 0.004, respectively). These 3 prognostic indexes were used to design a model to predict an individual patient's risk factor for recurrence. Patients were then assigned to one of the 4 risk groups according to the score achieved in this prognostic index (0=low risk, 1=intermediate risk, and 2 or 3=higher risk). These 4 risk groups had distinctly different rates of disease-free survival, i.e., 91.7%, 53%, 13%, and 7% for low, intermediate, and higher risk groups, respectively. CONCLUSION: Although this prognostic index appears to be of a significant clinical relevance, it needs to be more validated on a larger number of patients, and it could be a surrogate variable for biologic factors responsible for the heterogeneity of bladder cancer.

Cytokine-mediated host responses during schistosome infections; walking the fine line between immunological control and immunopathology.

Most helminth infections of humans and animals induce similar immune responses, which are characterised by the production of Th2-associated cytokines (interleukin (IL)-4, IL-5, IL-9, IL-10, IL-13) and antibodies (IgG1--mouse, IgG4--man, IgE--both). This type-2-biased immune phenotype generally persists for the duration of the infection. Although similar types of immune responses are also triggered during allergy, atopy and anaphylaxis, chronic helminth-induced type-2-associated responses are usually held in check by appropriately regulated control mechanisms that limit the destructive potential of prolonged cytokine bias. Among numerous reported activities, helminth-induced type-2-associated immune responses have been linked to the expulsion of gastrointestinal nematodes and the formation of circumoval granulomas during schistosomiasis. However, what happens when this highly regulated, and often beneficial, type-2 immune response becomes chronic, improperly controlled, or exaggerated during helminth infections? Using schistosomiasis as a model disease, we describe the lethal consequences of inappropriate immune response induction by reviewing the literature generated from experimental animal studies and human epidemiological investigations. Development of severe and non-overlapping immunopathological phenotypes will be discussed in the context of immune deviation and in the setting of chronic and/or hyper-polarised cytokine environments.

Impact of type and stage of schistosomiasis on quality of life and productivity of infected workers.

All workers with schistosomiasis (205 workers) during the field period (April 1998 to March 1999) were included. The study tools included an interviewing schedule, the WHO QOL-brief and a production data format specially designed to obtain data about the productivity of the workers. The data revealed that 78.8% of the schistosomiasis workers suffered from Schistosoma mansoni while only 7.6% suffered from S. haematobium and 13.5% had a mixed infection. Workers infected with S. mansoni tended to have lower mean percent of all the QOL domains and productivity indicators compared with workers infected with S. haematobium but these differences were not statistically significant. Workers with complications of schistosomiasis had significantly lower values for the QOL physical, social relationship and environmental domains (55.27 +/- 15.59, 74.94 +/- 5.34 and 56.39 +/- 15.09 versus 61.38 +/- 5.74, 79.36 +/- 11.96 and 61.64 +/- 7.74 respectively). Moreover, the production score was significantly lower in the workers with complication compared with workers free from schistosomiasis complications. The mean percent of QOL domains decreased as the stage of schistosomiasis increased from stage 1 to stage 4, this was statistically significant for the physical and independence domain. The mean additional hours and production scores decreased successively from stage 1 to stage 4 of schistosomiasis. Thus, special attention should be paid to schistosomiasis workers for early detection and treatment of complications to improve the QOL and increase the productivity of those workers. The impact of the stage of schistosomiasis on productivity and QOL of workers needs further research with a wide spectrum of workload in different industries.

Progress in the control of schistosomiasis in Zimbabwe since 1984.

Schistosomiasis remains the second most important parasitic disease in Zimbabwe. In terms of its combined morbidity and prevalence, schistosomiasis is thought to be the most important helminth infection of man. Since 1984, a number of control programmes have commenced around the country and a national control programme aimed at reducing morbidity is being implemented. The strategy adopted in Zimbabwe is a community based approach integrated in the primary health care system.

PIP: Health facility utilization surveys in Zimbabwe indicate that schistosomiasis is 1 of the top 10 causes of clinic attendance, especially for children. It is in fact the second most important helminth infection of man. Poor nutrition and work performance in children, and pathological changes in the liver, bladder, and kidneys are associated with schistosomiasis. Various control projects established in Zimbabwe since 1984 are reviewed, beginning with results of the nationwide survey reported by Taylor and Makura assessing levels of Schistosoma haemotobium and Schistosoma mansoni among 14,614 school children from 157 schools around the country. Prevalence was found to range from zero to 97%. While the community and irrigation scheme pilot control projects combined with the overall national strategy should reduce the prevalence and morbidity of schistosomiasis, closer intersectoral cooperation is needed between governmental departments, provinces, and donor agencies, as well as better integration between the schistosomiasis control program and ongoing PHC activities.

[Glomerulopathies in schistosomiasis. Current data]. / Les glomérulopathies au cours des schistosomiases Données actuelles.

The authors studied various glomerular injuries in schistosomiasis. They occurred more after with Schistosoma mansoni and rarely with other Schistosoma species. Different lesions were observed: the membrano-proliferative type is frequently noted; but mesangial and extramembranous glomerulitis were also described. The pathology of glomerular lesions is Immune mediated with activation of complement patway and deposit of immune circulating complexes.

Parasitic infections of the central nervous system.

The authors give a comprehensive review of the epidemiology, clinical presentations, diagnosis and current therapy of parasitic infections with CNS manifestations in both the normal and immunocompromised host. These include toxoplasmosis, malaria, amebiasis, neurocystcersosis, hydatid disease, and trichinosis. Additional sections cover disseminated strongyloidiasis, eosinophilic meningitis, visceral and ocular larva migrans, schistosomiasis, and cerebral paragonimiasis. Emphasis is on the neurologic complications of these diseases and their presentations in populations at increased risk for acquiring or reactivating these infections.

Incapacitating effects of schistosomiasis mansoni on the productivity of sugar-cane cutters in northeastern Brazil.

Studies were carried out on two sugar estates in the humid coastal forest region of northeastern Brazil, a highly endemic area of schistosomiasis mansoni. Results obtained in a retrospective study were not conclusive, but clear-cut results emerged from a prospective study. The latter was conducted on a sugar estate (Catende) where the severe hepatosplenic clinical form of the disease is seen in 4% of the field-working population. Comparison was made between two groups of paired subjects: one composed of workers with the hepatosplenic form of the disease and the other composed of workers with the intestinal form. Reduction of productivity among the hepatosplenic subjects compared to intestinal subjects was 35.1%. The loss to the Catende sugar estate from reduced productivity caused by schistosomiasis mansoni for the harvest season of 1978 was calculated as 0.93% of the estate's total production, or approximately US$135,000. When this figure is extrapolated to the State of Pernambuco (16 million tons of sugar total annual production), the annual loss in the state if estimated to be US$2 million.