Prevalence and intensity of Schistosoma haematobium infection among schoolchildren in central Zambia before and after mass treatment with a single dose of praziquantel

Schistosome Infection Impacts Hematopoiesis

Helminth infections are common in animals. However, the impact of a helminth infection on the function of hematopoietic stem cells (HSCs) and other hematopoietic cells has not been comprehensively defined. In this article, we describe the hematopoietic response to infection of mice with Schistosoma mansoni, a parasitic flatworm that causes schistosomiasis. We analyzed the frequency or number of hematopoietic cell types in the bone marrow, spleen, liver, thymus, and blood and observed multiple hematopoietic changes caused by infection. Schistosome infection impaired bone marrow HSC function after serial transplantation. Functional HSCs were present in the infected liver. Infection blocked bone marrow erythropoiesis and augmented spleen erythropoiesis, observations consistent with the anemia and splenomegaly prevalent in schistosomiasis patients. This work defines the hematopoietic response to schistosomiasis, a debilitating disease afflicting more than 200 million people, and identifies impairments in HSC function and erythropoiesis.

Coverage and predictors of the uptake of the mass drug administration of praziquantel chemotherapy for schistosomiasis in a selected urban setting in Zambia

The burden of schistosomiasis in Zambia has remained high over the years. The World Health Assembly recommended adequate mass drug administration coverage for schistosomiasis using Praziquantel chemotherapy for school-aged children and all at-risks adults. We aimed at investigating the coverage and the factors associated to the uptake for MDA for schistosomiasis in Ng'ombe township of Lusaka, Zambia. A cross-sectional survey was conducted in May and June 2021 via phone calls to the residents of Ng'ombe township. Commcare software was used in the conduct of the survey. Pearson's Chi-square test and multiple logistic regression were conducted using the STATA version 15.0. 769 study participants were randomly selected using systematic sampling, of which 76.3% were younger than 40 years, 64.9% were female, 64.4% were married, 56.3% had reached the secondary educational level and 51.9% were employed. Coverage for MDA for schistosomiasis in Ng'ombe township in 2018 was found to be 49.8% (95% CI: 46.2%-53.4%). Positive predictors of the MDA were prior knowledge of the occurrence of the MDA in 2018 (aOR: 2.892, p < 0.001) and believing that the provision of incentives like snacks was important during the MDA with PZQ in Ng'ombe township (aOR: 1.926, p = 0.001), whereas age (aOR:0.979, p = 0.009), marital status (aOR:0.620, p = 0.006), employment status (aOR:0.587, p = 0.001) were negative predictors of the MDA. Elimination of the burden of schistosomiasis in endemic settings needs the attainment of an optimum coverage and uptake during MDA with PZQ. Therefore, prior knowledge about an impending intervention and the provision of incentives like snacks during the intervention should be prioritized by MDA implementers, while background characteristics such as age, marital status, and employment status need to be taken into consideration when planning and promoting uptake in future MDAs.

Helminth infection impacts hematopoiesis

Helminth infections are common in animals. However, the impact of a helminth infection on the function of hematopoietic stem cells (HSCs) and other hematopoietic cells has not been comprehensively defined. Here we describe the hematopoietic response to infection of mice with Schistosoma mansoni, a parasitic flatworm which causes schistosomiasis. We analyzed the frequency or number of hematopoietic cell types in the bone marrow, spleen, liver, thymus, and blood, and observed multiple hematopoietic changes caused by infection. Schistosome infection impaired bone marrow HSC function after serial transplantation. Functional HSCs were present in the infected liver. Infection blocked bone marrow erythropoiesis and augmented spleen erythropoiesis, observations consistent with the anemia and splenomegaly prevalent in schistosomiasis patients. This work defines the hematopoietic response to schistosomiasis, a debilitating disease afflicting more than 200 million people, and identifies impairments in HSC function and erythropoiesis.

Schistosomiasis with a Focus on Africa

Schistosomiasis is a common neglected tropical disease of impoverished people and livestock in many developing countries in tropical Africa, the Middle East, Asia, and Latin America. Substantial progress has been made in controlling schistosomiasis in some African countries, but the disease still prevails in most parts of sub-Saharan Africa with an estimated 800 million people at risk of infection. Current control strategies rely primarily on treatment with praziquantel, as no vaccine is available; however, treatment alone does not prevent reinfection. There has been emphasis on the use of integrated approaches in the control and elimination of the disease in recent years with the development of health infrastructure and health education. However, there is a need to evaluate the present status of African schistosomiasis, primarily caused by Schistosoma mansoni and S. haematobium, and the factors affecting the disease as the basis for developing more effective control and elimination strategies in the future. This review provides an historical perspective of schistosomiasis in Africa and discusses the current status of control efforts in those countries where the disease is endemic.

A meta-analysis of changes in schistosomiasis prevalence in Zambia: implications on the 2020 elimination target

Schistosomiasis affects more than 4 million school-aged children in Zambia, mostly in rural communities due to unsafe water and inadequate sanitation facilities. Although several studies were done in Zambia between 1976 and 2019, empirical estimates of the disease burden remain unavailable. Therefore, appraisal of the current schistosomiasis burden is pertinent in the re-evaluation of schistosomiasis-control strategies in Zambia. A random-effect model was used to estimate the prevalence of schistosomiasis infection in Zambia across different age groups for the period between 1976 and 2019. A literature search was done in the following databases: PubMed, ISI Web of Science, Google Scholar, CINAHL, and African Journals Online. Twenty-eight studies with relevant prevalence data were identified and included in the analysis. The pooled prevalence estimate of Schistosoma haematobium and Schistosoma mansoni across studies for the entire period was 35.5% (95% CI: 25.8-45.9) and 34.9% (95% CI: 20.7-50.6), respectively. Prevalence estimates among school-aged children for S. haematobium and S. mansoni were 32.2% (95% CI: 21.1-44.7) and 18.1% (95% CI: 3.0-38.4), respectively. The reported pooled prevalence estimate for S. haematobium among the adults was 54% (95% CI: 23.2-83.7). Only two studies collected information from preschool aged children. Substantial heterogeneity (I² = 100%, p < 0.0001) was observed among the studies. Although a reduction in disease prevalence was observed from 1990 to 2010, this was not sustained after 2010. In this meta-analysis, S. haematobium was more prevalent compared to S. mansoni, with more cases observed among school-aged children (SAC). Thus, control programs should target age groups that are highly infected or are at high risk of infection.

Differential impact of mass and targeted praziquantel delivery on schistosomiasis control in school-aged children: A systematic review and meta-analysis

Background

Schistosomiasis is a widespread public health concern in the poorest regions of the world. The principal control strategy is regular praziquantel administration to school-aged children in endemic areas. With calls for the elimination of schistosomiasis as a public health problem, expanding praziquantel delivery to all community members has been advocated. This systematic review and meta-analysis compares the impact of community-wide and child-targeted praziquantel distribution on schistosomiasis prevalence and intensity in school-aged children.

Methodology/Principal findings

We searched MEDLINE, Embase and Web of Science to identify papers that reported schistosome prevalence before and after praziquantel administration, either to children only or to all community members. Extracted data included Schistosoma species, drug administration strategy, number of treatment rounds, follow-up interval and prevalence and intensity before and after treatment. We used inverse variance weighted generalised linear models to examine the impact of mass versus targeted drug administration on prevalence reduction, and weighted boxplots to examine the impact on infection intensity reduction. This study is registered with PROSPERO, number CRD42018095377.

In total, 34 articles were eligible for systematic review and 28 for meta-analysis. Schistosoma mansoni was reported in 20 studies; Schistosoma haematobium in 19 studies, and Schistosoma japonicum in two studies. Results of generalised linear models showed no detectable difference between mass and targeted treatment strategies on prevalence reduction in school-aged children for S. mansoni (odds ratio 0.47, 95%CI 0.13–1.68, p = 0.227) and S. haematobium (0.41, 95%CI 0.06–3.03, p = 0.358). Box plots also showed no apparent differences in intensity reduction between the two treatment strategies.

Conclusions/Significance

The results of this meta-analysis do not support the hypothesis that community-wide treatment is more effective than targeted treatment at reducing schistosomiasis infections in children. This may be due to the relatively small number of included studies, insufficient treatment coverage, persistent infection hotspots and unmeasured confounders. Further field-based studies comparing mass and targeted treatment are required.

Schistosomiasis is a neglected tropical disease, caused by parasitic worms, that affects more than 143 million people worldwide. Chronic infections can lead to significant morbidity including kidney damage, anaemia, malnutrition, infertility and growth impairment. School-aged children between six and 15 years are often targeted for regular treatment with praziquantel in large-scale drug delivery programs, because they suffer a disproportionate burden of morbidity. On the other hand, a mass drug delivery strategy that treats all members of the community has been suggested in a move towards elimination of schistosomiasis as a public health problem. In this systematic review, we assess the impact of community-wide versus children-only praziquantel distribution in reducing schistosomiasis infections in school-aged children. We did not detect a difference between mass and targeted treatment strategies, possibly due to factors including insufficient treatment coverage and persistent sources of reinfection. Addressing these factors may assist in optimising control programs.

Identification of newly developed advanced schistosomiasis with MALDI-TOF mass spectrometry and ClinProTools analysis

Cases of newly developed advanced schistosomiasis (NDAS) have occurred in areas where schistosomiasis transmission has been blocked for more than 25 years. The causes and pathogenesis of NDAS are still unknown. Diagnosis of NDAS relies on historical investigation and clinical symptoms, such as liver fibrosis, hepatic ascites and abnormal biochemical indexes in serum. It is important but difficult at this stage to develop a new tool for early screening and rapid diagnosis. In this study, serum peptides from thirty patients with NDAS and thirty healthy controls were captured with weak cation exchange magnetic beads, and subjected to MALDI-TOF mass spectrometry and ClinProTools analysis. Eleven peaks with m/z 924, 2661, 2953, 2991, 3241, 3884, 5337, 5905, 5943, 7766 and 9289 were decreased and three peaks with m/z 1945, 2082 and 4282 were increased in the NDAS group. The proteomic detection pattern (PDP) was established with 14 different peptide peaks, and its sensitivity and specificity were investigated with a blind test. The peptide mass fingerprints of sera from 50 NDAS patients and 100 healthy controls were double-blind subjected to the PDP method, and 50 patients and 92 healthy controls were classified as NDAS and healthy separately, which showed 100% sensitivity and 92% specificity. Our results showed that the PDP could be a new and useful method to detect NDAS.