Epidemiology of schistosomiasis in two high-risk communities of south Cote d'Ivoire with particular emphasis on pre-school-aged children

Prevalence of schistosomiasis among school children at Esuekyir community in the Central Region of Ghana

Schistosomiasis, an endemic neglected tropical disease in areas with poor sanitation, causes physical and mental defects in both children and adults. Various strategies, especially drug administration for morbidity control, have been implemented to combat the disease in Ghana and globally. Despite these efforts, schistosomiasis remains prevalent in Ghana, negatively impacting children's academic performance, growth, and overall quality of life. This study aimed to determine the prevalence of schistosomiasis in school children at Esuekyir, a peri-urban community in Ghana. A cross-sectional study using simple random sampling technique to select participants and collect stool and urine samples from 246 school children in Esuekyir was adopted. Microscopy of urine and stool samples was performed involving urine sedimentation and stool formol-ether sedimentation techniques to analyse for parasite eggs. Questionnaires were developed to help detect risk factors that expose these children to the disease. The prevalence of urogenital schistosomiasis in children at Esuekyir was 15.45% while that of intestinal schistosomiasis was 6.957.0%. There was one case of co-infection of urogenital and intestinal schistosomiasis from a 13 year old primary student. Children in primary school had higher risks of infection due to their activities around the water body. There was a significant association between class groups and urogenital schistosomiasis (p-value = 0.042). The presence of schistosomiasis in school children highlights the importance of targeted interventions and public health initiatives in addressing this specific disease condition especially in primary school children. Findings from the research revealed a higher prevalence of urogenital schistosomiasis in the study population as compared to intestinal schistosomiasis.

Community preferred drug delivery approaches for pilot roll-out of a potential novel paediatric schistosomiasis treatment option in two endemic counties of Kenya: A mixed methods study

Treating preschool age children (PSAC) for schistosomiasis has remained a challenge due to lack of a pediatric formulation. In response to this unmet need, the Paediatric Praziquantel Consortium has developed a potential novel paediatric treatment option. In advance to its roll-out to follow regulatory response, we conducted a social science study to gather information on preferred drug delivery approaches to inform implementation. A cross-sectional study was conducted in eight villages in two purposively selected Kenyan counties. A questionnaire was administered on 690 parents/guardians of PSAC at household level. Preferred drug delivery approaches were analyzed using frequencies and proportions. We conducted key informant interviews with 17 opinion leaders and 28 healthcare workers, and 12 focus group discussions with parents/guardians of PSAC and 7 with community health volunteers (CHVs). Thematic analysis was performed on the qualitative data. Majority of the 690 respondents were women 594 (86.1%) with a mean age of 34.1 (SD = 11.3, min-max = 18-86). Community-based mass drug administration (cMDA) was the most preferred drug delivery method by 598 participants (86.7%), followed by health facility/fixed points by 398 participants (57.7%). Similarly, in the qualitative data participants indicated they prefer cMDA since the CHVs who would distribute the medication are familiar with households with PSAC and are trusted to explain the drug effects. Health facilities/fixed points were the second most preferred drug delivery approach, but some health workers we interviewed expressed concern about potential understaffing and overcrowding of facilities. Appropriate timing of the drug distribution, not to interfere with farming activities, was considered critical, irrespective of the approach used. All profiles of study participants preferred cMDA over the other delivery approaches due to the convenience of receiving drugs at home and providing explanations about the new drug. For positive outcomes, adequate planning, proper timings and community involvement are highly recommended.

Evaluating the Prevalence and Risk Factors of Schistosomiasis Amongst School-Aged Children in Low- and Middle-Income Communities: Ehlanzeni District Municipality, South Africa, 2015-2021

This study aimed to assess the prevalence and identify risk factors of schistosomiasis among school-aged children in low- and middle-income communities. A retrospective cross-sectional study was conducted to review patient records of school-age children. Data on gender, age, sub-district, area residing in, patient status, history of bilharzia, presence of blood in the urine, and schistosomiasis diagnoses were collected. The data were analyzed using IBM Statistical Package for the Social Sciences (SPSS) version 27. Logistic regression was employed to determine the factors associated with schistosomiasis. The overall prevalence of schistosomiasis in the study population was 75%, with higher prevalence observed among male children (89%), children aged between 10 and 14 years (59%), urban areas (51%), and rural-dominated districts, particularly Bushbuckridge (42%) and City of Mbombela (51%). Age, especially 10-14 years old (p ˂ 0.01; 95%CI: 1.98-2.29), a history of bilharzia (p = 0.01; 95%CI: 1.15-1.96), and the presence of blood in urine (p ˂ 0.01; 95%CI: 2.02-2.40) were significantly associated with schistosomiasis while being a female child was found to be a protective factor (AOR: 0.35; CI 0.35-0.41). This study underscores the importance of implementing robust screening procedures and the necessity for health education to mitigate the high prevalence of schistosomiasis and prevent its further spread.

Screening for Resistant Bacteria, Antimicrobial Resistance Genes, Sexually Transmitted Infections and Schistosoma spp. in Tissue Samples from Predominantly Vaginally Delivered Placentae in Ivory Coast and Ghana

Medical complications during pregnancy have been frequently reported from Western Africa with a particular importance of infectious complications. Placental tissue can either become the target of infectious agents itself, such as, e.g., in the case of urogenital schistosomiasis, or be subjected to contamination with colonizing or infection-associated microorganisms of the cervix or the vagina during vaginal delivery. In the retrospective cross-sectional assessment presented here, the quantitative dimension of infection or colonization with selected resistant or pathogenic bacteria and parasites was regionally assessed. To do so, 274 collected placental tissues from Ivory Coastal and Ghanaian women were subjected to selective growth of resistant bacteria, as well as to molecular screening for beta-lactamase genes, Schistosoma spp. and selected bacterial causative agents of sexually transmitted infections (STI). Panton-Valentine-negative methicillin-resistant Staphylococcus aureus (MRSA) was grown from 1.8% of the tissue samples, comprising the spa types t008 and t688, as well as the newly detected ones, t12101 (n = 2) and t12102. While the culture-based recovery of resistant Enterobacterales and nonfermentative rod-shaped Gram-negative bacteria failed, molecular assessments confirmed beta-lactamase genes in 31.0% of the samples with multiple detections of up to four resistance genes per sample and blaCTX-M, blaIMP, blaGES, blaVIM, blaOXA-58-like, blaNDM, blaOXA-23-like, blaOXA-48-like and blaKPC occurring in descending order of frequency. The beta-lactamase genes blaOXA-40/24-like, blaNMC_A/IMI, blaBIC, blaSME, blaGIM and blaDIM were not detected. DNA of the urogenital schistosomiasis-associated Schistosoma haematobium complex was recorded in 18.6% of the samples, but only a single positive signal for S. mansoni with a high cycle-threshold value in real-time PCR was found. Of note, higher rates of schistosomiasis were observed in Ghana (54.9% vs. 10.3% in Ivory Coast) and Cesarean section was much more frequent in schistosomiasis patients (61.9% vs. 14.8% in women without Schistosoma spp. DNA in the placenta). Nucleic acid sequences of nonlymphogranuloma-venereum-associated Chlamydia trachomatis and of Neisseria gonorrhoeae were recorded in 1.1% and 1.9% of the samples, respectively, while molecular attempts to diagnose Treponema pallidum and Mycoplasma genitalium did not lead to positive results. Molecular detection of Schistosoma spp. or STI-associated pathogens was only exceptionally associated with multiple resistance gene detections in the same sample, suggesting epidemiological distinctness. In conclusion, the assessment confirmed considerable prevalence of urogenital schistosomiasis and resistant bacterial colonization, as well as a regionally expected abundance of STI-associated pathogens. Continuous screening offers seem advisable to minimize the risks for the pregnant women and their newborns.

Image-Based Awareness Campaign and Community Mobilization in the Control of Schistosomiasis

Community awareness and participation in mass screening is critical for schistosomiasis control. This study assessed the impact of sharing anonymized image-based positive test results on the uptake of screening during community mobilization outreach. We conducted an observational study to compare the population response to standard and image-based strategies in 14 communities in Abuja, Nigeria. Six hundred and ninety-one (341 females, 350 males) individuals participated in this study. We analyzed the response ratio, relative increase, and sample collection time. The potential treatment uptake and change in social behavior were determined based on a semi-structured questionnaire. The mean response ratio of the image-based strategy was 89.7% representing a significantly higher ratio than the 27.8%, which was observed under the standard mobilization approach (p ≤ 0.001). The image-based method was associated with 100% of the participants agreeing to provide urine samples, 94% willing to be treated, 89% claiming to have been invited to participate in the study by a friend, and 91% desiring to change a predisposing behavioral habit. These findings indicate that image-based community awareness campaigns may increase the population's perception about schistosomiasis transmission and treatment. This raises new possibilities for local resource mobilization to expand services in reaching the last mile in schistosomiasis control.

Optimizing Implementation of Preventive Chemotherapy against Soil-Transmitted Helminthiasis and Intestinal Schistosomiasis Using High-Resolution Data: Field-Based Experiences from Côte d’Ivoire

Background: Despite efforts to control neglected tropical diseases (NTDs) using preventive chemotherapy (PC), soil-transmitted helminthiases and schistosomiasis remain widely prevalent in sub-Saharan Africa. The current PC regimen in endemic settings is defined based on health district-level prevalence. This work aims to highlight the need for high-resolution data when elimination, rather than morbidity control, is the targeted goal. Methodology: Cross-sectional parasitological surveys were conducted from July to August 2019 and from September to October 2019, respectively, across the entire Dabou and Jacqueville health districts in southern Côte d’Ivoire. From every village, 60 school-aged children (6–15 years) were randomly selected and invited to provide one fresh stool sample, whereof duplicate Kato–Katz thick smears were prepared and read by two independent technicians. Principal Findings: 4338 school-aged children from 77 villages were screened from the Dabou (n = 2174; 50.12%, 39 villages) and Jacqueville (n = 2164; 49.88%, 38 villages) health districts. The prevalence of any soil-transmitted helminth (STH) infection was 12.47% and 11.09% in the Dabou and Jacqueville health districts, respectively. Species-specific district-level prevalence remained below 10%, varying between 0.51% (hookworm in Jacqueville) and 9.06% (Trichuris trichiura in Dabou). However, when considering sub-districts or villages only, several STH infection hotspots (five sub-districts with ≥20% and four villages with more than 50% infected) were observed. Schistosoma mansoni infection was found in less than 1% of the examined children in each health district. Conclusions/Significance: We conclude that keeping health district-level prevalence as a reference for PC implementation leaves many high-risk sub-districts or villages requiring PC (≥20% prevalence) untreated. To avoid maintaining those high-risk villages as STH reservoirs by skipping control interventions and jeopardizing the successes already achieved in STH control through PC during the past two decades, precision mapping is required. Further investigation is needed to assess cost-efficient approaches to implement small-scale disease surveillance.

Population genetic structure of Schistosoma haematobium and Schistosoma haematobium × Schistosoma bovis hybrids among school-aged children in Côte d'Ivoire

While population genetics of Schistosoma haematobium have been investigated in West Africa, only scant data are available from Côte d’Ivoire. The purpose of this study was to analyze both genetic variability and genetic structure among S. haematobium populations and to quantify the frequency of S. haematobium × S. bovis hybrids in school-aged children in different parts of Côte d’Ivoire. Urine samples were subjected to a filtration method and examined microscopically for Schistosoma eggs in four sites in the western and southern parts of Côte d’Ivoire. A total of 2692 miracidia were collected individually and stored on Whatman^® FTA cards. Of these, 2561 miracidia were successfully genotyped for species and hybrid identification using rapid diagnostic multiplex mitochondrial cox1 PCR and PCR Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of the nuclear ITS2 region. From 2164 miracidia, 1966 (90.9%) were successfully genotyped using at least 10 nuclear microsatellite loci to investigate genetic diversity and population structure. Significant differences were found between sites in all genetic diversity indices and genotypic differentiation was observed between the site in the West and the three sites in the East. Analysis at the infrapopulation level revealed clustering of parasite genotypes within individual children, particularly in Duekoué (West) and Sikensi (East). Of the six possible cox1-ITS2 genetic profiles obtained from miracidia, S. bovis cox1 × S. haematobium ITS2 (42.0%) was the most commonly observed in the populations. We identified only 15 miracidia (0.7%) with an S. bovis cox1 × S. bovis ITS2 genotype. Our study provides new insights into the population genetics of S. haematobium and S. haematobium × S. bovis hybrids in humans in Côte d’Ivoire and we advocate for researching hybrid schistosomes in animals such as rodents and cattle in Côte d’Ivoire.

Prevalence of S. mansoni Infection and Associated Risk Factors among School Children in Guangua District, Northwest Ethiopia

Methods

A cross-sectional study design was employed. Four hundred twenty-two participants were selected. Data was collected through observation and interview with structured questionnaire. Stool specimens were collected and examined using two-slide Kato-Katz method. The data were analyzed using SPSS version 23. Logistic regression was fitted for analysis. Variables with p value <0.25 in the univariate logistic regression analysis were entered into the multivariable logistic regression model. Those with <0.05 were identified as significantly associated risk factors. To assure the quality of the data, training was given for data collectors and supervisors, and the tools were pretested on 5% of the sample size.

Results

404 (95.7%) school children were enrolled in the study. The overall prevalence of S. mansoni was 12.6%. School children in the age group 5-9 years old (AOR (95% CI): 22.27 (3.70-134.01), p = 0.001), age group 10-14 years old (AOR (95% CI): 4.58 (1.14-18.42), p = 0.032), grade levels 5-8 (AOR (95% CL): 14.95 (4.297-52.03), p = 0.001),who swim frequently (AOR (95% CI): 11.35 (2.33-55.33), p = 0.003), and those who cultivate near the irrigation area (AOR (95% CI): 7.10 (2.31-21.80), p = 0.001) were significantly associated with high risk of S. mansoni infection. Conclusion and Recommendation. From the finding of the current study, it can be concluded that the prevalence of Schistosoma mansoni in the study area is relatively high. Age of fourteen and younger years old, swimming in the river, and irrigation practice were the main risk factors of S. mansoni infection. Thus, therapeutic interventions as well as health education are desirable.

Comparison of quantitative polymerase chain reaction, Kato-Katz and circulating cathodic antigen rapid test for the diagnosis of Schistosoma mansoni infection: A cross-sectional study in Kirinyaga County, Kenya

The current standard diagnostic tests for Schistosoma mansoni are the Kato-Katz and circulating cathodic antigen (CCA) techniques. However, these techniques have been documented to have several limitations that have a direct impact on schistosomiasis control programmes. Therefore, there is a need for more sensitive and specific tests for diagnosing schistosomiasis. This study compared the performance of quantitative polymerase chain reaction (qPCR), Kato-Katz, and point-of-care circulating cathodic antigen (POC-CCA) techniques in the diagnosis of S. mansoni infection in the Mwea irrigation scheme, Kirinyaga County in Central Kenya. We carried out a cross-sectional study on 357 individuals residing in four villages in the Mwea irrigation scheme. The participants provided urine and stool samples which were screened for S. mansoni infections using the three techniques. The prevalence of S. mansoni by each technique was calculated and 95% confidence intervals estimated using binomial regression model. Sensitivity and specificity were determined using 2 × 2 contingency tables and compared using the McNemar’s chi-square test. Positive and negative predictive values were also determined using the weighted generalized score chi-square test for paired data. The study showed that the prevalence of S. mansoni was 32.8%, 62.5% and 72.8% using Kato-Katz, POC-CCA and qPCR techniques, respectively. Further, when using Kato-Katz as a gold standard, POC-CCA sensitivity was 78.6% and specificity was 45.4%, while qPCR sensitivity was 97.4% and specificity was 39.2%. When using qPCR as the gold standard, Kato-Katz sensitivity was 43.8% and specificity was 96.9%, while POC-CCA sensitivity was 78.1% and specificity was 79.4%. Finally, when using the averaged results from the three techniques as the gold standard, the sensitivity was 41.6%, 79.4% and 92.5% for Kato-Katz, POC-CCA and qPCR, respectively, with a specificity of 100% for all techniques. Kato-Katz technique showed low sensitivity compared to the POC-CCA and qPCR despite it being the most commonly preferred method of choice to diagnose S. mansoni infections. qPCR showed superior sensitivity followed by POC-CCA, hence it can be used as an alternative or to confirm the results obtained by the Kato-Katz technique.

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Comparison of the performance of Kato-Katz, POC-CCA and qPCR for diagnosis of S. mansoni in Kirinyaga County, Kenya.

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A total of 357 urine and stool samples were tested for S. mansoni infection.

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qPCR estimated the highest prevalence followed by POC-CCA and Kato-Katz.

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qPCR showed a generally high sensitivity and specificity.

Risk Factors and Spatial Distribution of Schistosoma mansoni Infection among Preschool-Aged Children in Blapleu, Biankouma District, Western Côte d'Ivoire

Schistosoma mansoni infection is common among school-age children (SAC) in western Côte d'Ivoire. Little is known on the infection rate of preschool-aged children (PSAC) due to epidemiological data deficiency and nonappropriate formulation of the drug. Thus, mass drug administration for schistosomiasis control mainly targets SAC. This study aims to identify the risk factors and spatial distribution of S. mansoni infection among PSAC in Blapleu, endemic foci of S. mansoni. We carried out a cross-sectional study in households with PSAC aged 1–6 years. A structured questionnaire was administered to mothers/guardians to obtain data on sociodemographics and water contact behaviour of children. Point-of-care circulating cathodic antigen (POC-CCA) immunodiagnostic test in urine and Kato-Katz (K-K) method with stool were used for S. mansoni infection diagnosis. Multiple logistic regression analysis was performed to determine the relationship between S. mansoni infection and sociodemographic data. Coordinates recorded by a Global Positioning System of households, water source points, and infected PSAC were used to map the spatial distribution of S. mansoni infection cases. This study was conducted with 350 PSAC aged 1–6 years. The overall infection prevalence of S. mansoni varies from 31.43% with the K-K method to 62.86% with the POC-CCA. PSAC aged 2–6 years were highly infected with S. mansoni than those aged 1-2 years (OR = 14.24, 95% CI: 5.85–34.64). PSAC who did not have access and who do not live close to the infected water source were at a significant lower risk of S. mansoni infection (OR = 0.13, 95% CI: 0.057–0.30). The main purpose of water contact of PSAC was to help their mother for laundry that occurs weekly. In Blapleu, a high risk of S. mansoni infection was observed among PSAC. Schistosomiasis control effort in such localities should include information, education, and communication, water, sanitation, and hygiene, and particularly chemotherapy targeting PSAC, reinforcing the need of the paediatric praziquantel formulation.

Efficacy and Safety of New Orodispersible Tablet Formulations of Praziquantel (Racemate and L-Praziquantel) in Schistosoma mansoni-Infected Preschool-Age Children and Infants: A Randomized Dose-Finding Phase 2 Study

Introduction

Two novel formulations of praziquantel (PZQ) and Levo-(L-)PZQ (arpraziquantel) have been developed for the treatment of schistosomiasis in preschool-age children and infants.

Methods

This open-label, dose-finding Phase 2 study assessed the efficacy and safety of PZQ formulations in children and infants infected with Schisostoma mansoni in Côte d’Ivoire. In Part 1, 420 children aged 2.1–6.9 years (weight 10.0–29.9 kg) were enrolled and randomized to one of 7 treatment arms (n=60 per arm): commercially available racemate (rac)-PZQ at 3x20 mg/kg or 40 mg/kg (treatment arms 1 and 2); rac-PZQ orodispersible tablet (ODT) at 40 mg/kg or 60 mg/kg (treatment arms 3 and 4); or L-PZQ ODT at 30 mg/kg, 45 mg/kg, or 60 mg/kg (treatment arms 5, 6, and 7). The optimal formulation and dose identified (L-PZQ ODT 50 mg/kg) was used in Part 2, which enrolled 24 infants aged 6–24 months (weight 7.5–14.8 kg). Infants were treated in an age-staggered approach: age 13–24 months (treatment arm 8, n=20) and age 6–12 months (treatment arm 9, n=4). The primary endpoint was clinical cure rate (CR) demonstrated by the Kato–Katz method 14–21 days post-treatment. Secondary endpoints included CR by point-of-care circulating cathodic antigen, egg reduction rate (ERR), and adverse events (AEs).

Results

In Part 1, CRs ≥70% were achieved in all treatment arms and were highest with L-PZQ ODT 60 mg/kg (89.7%), rac-PZQ 3x20 mg/kg (89.5%), and L-PZQ ODT 45 mg/kg (86.0%). In Part 2, CRs were &gt;90%. All treatment arms had ERRs &gt;95%. Treatment-related AEs were reported by 71 participants (16.0%) and were similar across treatment arms; most were mild and transient. The most common treatment-emergent AEs were laboratory abnormalities. No deaths or discontinuation due to treatment-emergent AEs were reported and no new safety concerns were identified.

Conclusion

New rac-PZQ and L-PZQ ODT formulations used as single-dose therapy against S. mansoni demonstrated acceptable overall efficacy and safety in preschool-age children and infants, warranting further studies in this population.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT02806232; Pan African Clinical Trials Registry, identifier PACTR201604001493593.

Prevalence of urogenital and intestinal schistosomiasis among school children in South-west Nigeria

Background

The risk of co-infection with Schistosoma haematobium and S. mansoni and the potential harmful effect on morbidity and control is enhanced by the overlapping distribution of both species in sub-Saharan Africa. Despite the reported high endemicity of both species in Nigeria, studies on the spread and effect of their mixed infection are limited. Therefore, a cross-sectional survey was conducted among school children in two communities in South-west Nigeria to investigate the prevalence of mixed human schistosome infection, intensity, and possible ectopic egg elimination.

Methods

Urine and stool samples were collected from consenting school children in Ilie and Ore communities of Osun State, Nigeria. Schistosoma haematobium eggs were detected in urine using the urine filtration technique, while S. mansoni eggs were detected in stool using the Kato–Katz thick smear technique.

Results

The study enrolled 466 primary and secondary school children (211; 45.3% males vs. 255; 54.7% females; mean age 11.6 ± 3.16 years). The overall prevalence of schistosomiasis was 40% (185/466), with 19% (89/466) recording single S. haematobium infection while 9% (41/465) had a single S. mansoni infection. The geometric mean egg count for S. haematobium was 189.4 egg/10ml urine; 95% CI: range 115.9–262.9, while for S. mansoni, it was 115.7 epg; 95% CI: range 78.4–152.9. The prevalence of ectopic S mansoni (S. mansoni eggs in urine) was 4.7%, while no ectopic S. haematobium (S. haematobium eggs in stool) was recorded. Mixed infection of S. haematobium/S. mansoni had a prevalence of 9.5% (44/466). More females (54.5%) presented with S. haematobium/S. mansoni co-infection. For both parasites, males had higher infection intensity, with a significant difference observed with S. haematobium (p = 0.0004). Hematuria was significant in individuals with single S. haematobium infection (p = 0.002), mixed ectopic S. haematobium/S. mansoni (p = 0.009) and mixed S. haematobium/S. mansoni/ectopic S. mansoni (p = 0.0003).

Conclusions

These findings suggest the probability of interspecific interactions between S. haematobium and S. mansoni. Scaling up of mass administration of praziquantel and control measures in the study areas is highly desirable.

In sub-Saharan Africa, human schistosomiasis is a neglected disease of public health concern caused mostly by Schistosoma haematobium and Schistosoma mansoni. The overlapping range of both species in Africa considerably increases the chance of co-infection. School-aged children are the most vulnerable, as they participate in water contact activities that expose them to free-swimming cercariae released by infected snail species in freshwater. This study examined the probable mixed human Schistosoma infections and associated disease variables in school children in the communities of Ilie and Ore in southwest Nigeria. This study reveals a high prevalence of mixed S. haematobium and S. mansoni, and ectopic S. mansoni eggs (S. mansoni eggs in urine) elimination, highlighting the possible ongoing control challenges in this area. Furthermore, this study indicates that some form of inter-specific interaction exists between S. haematobium and S. mansoni, and may produce potentially significant consequences for developing morbidity in the study areas.

A 12-year follow-up of intestinal schistosomiasis in pre-school-aged children in Assoni Village, Eastern Senegal

Background

To monitor the prevalence of schistosomiasis in school-aged children (SAC), the National Bilharzia Control Program (PNLB) was set up by the Senegalese authorities; however, geographically isolated Bedik ethnic groups that did not benefit from this program were found to be heavily infected with Schistosoma mansoni. This observation led us to implement a new schistosomiasis control program in 2008 under the aegis of the non-governmental organization “Le Kaïcedrat” and in partnership with the PNLB/WHO to monitor the prevalence of schistosomiasis in this area. In the village of Assoni, where 100% of SAC were infected, analysis of the stools of pre-school-aged children (PSAC) showed that they were massively infected, so we decided to focus our program on them.

Methods

From 2008 to 2020, we (i) monitored the prevalence of S. mansoni in PSAC in Assoni using double-stool smear preparation, (ii) treated the infected PSAC with a standard dose of praziquantel 40 mg/kg, (iii) ran educational campaigns each year in the village, and (iv) built latrines to improve sanitation and reduce schistosomiasis transmission. Linear regression was used to examine the trend in the annual schistosomiasis prevalence and a two-sided of Chi-squared test was used to compare prevalence between the different age groups of PSAC.

Results

We observed an extremely high prevalence of schistosomiasis (78%) in PSAC before implementation of the program in 2008. Contamination occurred in very young children, as 64.3% of children under 2 years old were infected. Moreover, prevalence increased with age and reached 96.8% in children 4 to < 6 years old. Our annual interventions in Assoni Village raised awareness among villagers that water bodies were areas of significant infestation, allowed the building of 88 latrines and led to a decrease in prevalence in PSAC as only 11% of these children were infected in 2020.

Conclusion

Our study allowed Assoni to be the first village in Senegal to treat PSAC since 2014, but only on an individual basis. It also shows that schistosomiasis is difficult to eradicate and that multi-sectorial actions are required to keep its prevalence at a low level.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40249-021-00867-8.

Comparison of POC-CCA with Kato-Katz in Diagnosing Schistosoma mansoni Infection in a Pediatric L-Praziquantel Clinical Trial

Introduction

Traditionally Schistosoma mansoni infection is diagnosed by the Kato-Katz method. Thick smears from each stool sample are prepared on slides and eggs are counted microscopically. Commercially available point-of-care circulating cathodic antigen (POC-CCA) cassette tests detect schistosomiasis antigens from urine samples in 20 minutes. POC-CCA results are qualitative or semi-quantitative: signal intensity is an indicator of the amount of worm antigens in the sample. Both methods were used in a phase II trial investigating the efficacy and safety of new pediatric formulations of praziquantel (PZQ) among children ≤6 years (NCT02806232). This secondary analysis evaluated the consistency of results between the Kato-Katz and POC-CCA methods.

Methods

POC-CCA was used to pre-screen for S. mansoni infection. Children with positive results were tested by the Kato-Katz method, and those with positive Kato-Katz results (&gt;1 egg/1 occurrence) were enrolled. Participants (N=444) were treated with different formulations and doses of PZQ. POC-CCA and Kato-Katz were performed at 2–3 weeks after treatment to evaluate drug efficacy. Cure rate (CR) was defined as the proportion of participants with a negative result per POC-CCA, or no eggs in the stool samples per Kato-Katz. Kappa statistic was used to assess the agreement on cure status, and Spearman correlation between POC-CCA positivity and Kato-Katz egg counts was evaluated. Sensitivity and specificity of POC-CCA were calculated using Kato-Katz as a reference standard.

Results

CR per POC-CCA, measured 2–3 weeks after treatment, was 52% [95% confidence interval (CI): 48%, 57%] across all treatment arms except in infants aged 3–12 months. CR per Kato-Katz was 83% (95% CI: 79%, 87%). Kappa statistic was 0.16 (95% CI: 0.09, 0.23), indicating that the agreement was slightly better than by chance. Relative to Kato-Katz, POC-CCA’s sensitivity to detect infection was 70% and specificity was 57%. Spearman correlation coefficient between POC-CCA positivity and Kato-Katz egg counts was 0.26 (95% CI: 0.17, 0.34).

Conclusion

POC-CCA is sensitive and rapid for diagnosing S. mansoni infection, but its performance and consistency with Kato-Katz requires further investigation among young children.

Prevalence and risk factors of Schistosoma mansoni infection among preschool-aged children from Panamasso village, Burkina Faso

Background

Schistosomiasis remains a major public health concern in sub-Saharan Africa. Although schistosomiasis is well documented in school-aged children in Burkina Faso, prevalence data among preschool-aged children (PSAC) are limited and outdated, and its risk factors in this group remain poorly documented. The main objective of this study was to assess the prevalence and risk factors associated with Schistosoma (S.) mansoni infection among PSAC from Panamasso village, western Burkina Faso.

Methodology

A cross-sectional study was carried out among 228 children under 6 years old from Panamasso village. Sociodemographic and water contact data were collected using a structured questionnaire. Kato-Katz and formol-ether concentration techniques were used to detect S. mansoni eggs in stool samples. Urine samples were subjected to a point-of-care circulating cathodic antigen (POC-CCA) cassette test and a centrifugation method to check for both S. mansoni and S. haematobium infection, respectively. Potential risk factors for S. mansoni infection were explored using multivariable logistic regression.

Results

The mean age of children was 40.2 ± 15.0 months. The prevalence of S. mansoni infection as determined by Kato-Katz, formol-ether concentration and POC-CCA was 42.1%, 39.5% and 80.7%, respectively. Based on the combined results of the three methods, the overall prevalence of S. mansoni infection was 81.1%. No case of S. haematobium infection was found. The geometric mean intensity of S. mansoni infection was 107.2 eggs per gram of feces with 54.2%, 33.3% and 12.5% of the children having light, moderate and heavy infections, respectively. Girls (AOR = 2.9, 95% CI 1.3–6.1), a household located within 500 m from the pond (AOR = 3.0, 95% CI 1.0–8.6) or between 500 and 1000 m from the pond (AOR = 3.0, 95% CI 1.2–7.2), and the child’s history of going to the pond (AOR = 5.0, 95% CI 1.7–14.3) were the variables significantly associated with S. mansoni infection.

Conclusion

S. mansoni was the sole species infecting a high proportion of PSAC in the study area. A mass drug administration program with praziquantel is therefore urgently required for those below 6 years old. Other control strategies should include increased community-awareness and provision of safe water.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04692-8.

Immunological Considerations for Schistosoma Vaccine Development: Transitioning to Endemic Settings

Despite mass drug administration programmes with praziquantel, the prevalence of schistosomiasis remains high. A vaccine is urgently needed to control transmission of this debilitating disease. As some promising schistosomiasis vaccine candidates are moving through pre-clinical and clinical testing, we review the immunological challenges that these vaccine candidates may encounter in transitioning through the clinical trial phases in endemic settings. Prior exposure of the target population to schistosomes and other infections may impact vaccine response and efficacy and therefore requires considerable attention. Schistosomes are known for their potential to induce T-reg/IL-10 mediated immune suppression in populations which are chronically infected. Moreover, endemicity of schistosomiasis is focal whereby target and trial populations may exhibit several degrees of prior exposure as well as in utero exposure which may increase heterogeneity of vaccine responses. The age dependent distribution of exposure and development of acquired immunity, and general differences in the baseline immunological profile, adds to the complexity of selecting suitable trial populations. Similarly, prior or concurrent infections with other parasitic helminths, viral and bacterial infections, may alter immunological responses. Consequently, treatment of co-infections may benefit the immunogenicity of vaccines and may be considered despite logistical challenges. On the other hand, viral infections leave a life-long immunological imprint on the human host. Screening for serostatus may be needed to facilitate interpretation of vaccine responses. Co-delivery of schistosome vaccines with PZQ is attractive from a perspective of implementation but may complicate the immunogenicity of schistosomiasis vaccines. Several studies have reported PZQ treatment to induce both transient and long-term immuno-modulatory effects as a result of tegument destruction, worm killing and subsequent exposure of worm antigens to the host immune system. These in turn may augment or antagonize vaccine immunogenicity. Understanding the complex immunological interactions between vaccine, co-infections or prior exposure is essential in early stages of clinical development to facilitate phase 3 clinical trial design and implementation policies. Besides well-designed studies in different target populations using schistosome candidate vaccines or other vaccines as models, controlled human infections could also help identify markers of immune protection in populations with different disease and immunological backgrounds.

The use of non-pharmaceutical interventions for the prevention and control of schistosomiasis in sub-Saharan Africa: A systematic review

Schistosomiasis remains a major cause of global parasitic morbidity. Current control strategies focus on pharmaceutical approaches using Mass Drug Administration (MDA) to distribute praziquantel in endemic areas of sub-Saharan Africa. Our paper systematically reviewed the literature on non-pharmaceutical interventions for enhanced schistosomiasis control. We conducted a systematic review of peer-reviewed English language literature using PubMed, Embase and Web of Science. Our search terms were limited to the year 2000 to March 2019 to reflect the period of the Millennium and Sustainable Development Goals. We initially identified 1733 publications, which were reduced to 1324 after screening by title and abstract. After the inclusion and exclusion criteria, a total of 1312 studies were excluded. Following this, we had a total of 12 articles, which we later screened by full text. Out of the twelve articles, seven were excluded for being systematic reviews or examining clinical and nutritional aspects of schistosomiasis control. We finally remained with five studies that met our inclusion criteria. Our paper indicates a gap in non-pharmaceutical based interventions for schistosomiasis control. We propose that future research addresses this gap by engaging communities in participatory approaches such as environmental sanitation, Water, Sanitation and Hygiene (WASH), health education and economic empowerment.

Investigating a strategy for quantifying schistosome infection levels in preschool-aged children using prevalence data from school-aged children

In 2012, the World Health Organisation (WHO) set out a roadmap for eliminating schistosomiasis as a public health problem by 2025. To achieve this target, preschool-aged children (PSAC; aged 6 years and below) will need to be included in schistosomiasis treatment programmes. As the global community discusses the tools and approaches for treating this group, one of the main questions that remains unanswered is how to quantify infection in this age group to inform treatment strategies. The aim of this study was thus to determine whether a relationship exists between levels of schistosome infection in PSAC and school-aged children (SAC), that can be used to determine unknown schistosome infection prevalence levels in PSAC. A systematic search of publications reporting schistosomiasis prevalence in African PSAC and SAC was conducted. The search strategy was formulated using the PRISMA guidelines and SPIDER search strategy tool. The published data was subjected to regression analysis to determine if a relationship exists between infection levels in PSAC and SAC. The interaction between SAC and community treatment history was also entered in the regression model to determine if treatment history significantly affected the relationship between PSAC and SAC prevalence. The results showed that a significant positive relationship exists between infection prevalence levels in PSAC and SAC for Schistosoma mansoni (r = 0.812, df (88, 1), p = <0.0001) and S. haematobium (r = 0.786, df (53, 1), p = <0.0001). The relationship was still significant after allowing for diagnostic method, treatment history, and the African sub-region where the study was conducted (S. mansoni: F = 25.63, df (88, 9), p = <0.0001; S. haematobium: F = 10.20, df (53, 10), p = <0.0001). Using the regression equation for PSAC and SAC prevalence, over 90% of the PSAC prevalence studies were placed in the correct WHO classifications category based on the SAC levels, regardless of treatment history. The study indicated that schistosome prevalence in SAC can be extended as a proxy for infection levels in PSAC, extending on its current use in the adult population. SAC prevalence data could identify where there is a need to accelerate and facilitate the treatment of PSAC for schistosomiasis in Africa.

Preschool-aged children (PSAC), i.e. aged ≤ 6 years, are not included in preventative chemotherapy programmes, currently advocated by the WHO for the treatment of schistosomiasis. This is due to the lack of a paediatric formulation of the drug of choice, praziquantel, and the current guidelines which requires diagnosis before treatment. As the global community prepares for the deployment of a new paediatric formulation of praziquantel, there is a need to find a strategy to quantify infection in this age group. In schistosome endemic areas, infection levels in school-aged children (SAC) are already used to inform infection levels in the community. Thus, we investigated the relationship between SAC and PSAC schistosome prevalence levels within the same community, to determine if data from SAC could be used to predict infection levels in PSAC. Our results show that PSAC prevalence levels are significantly correlated with SAC prevalence levels. Our findings are applicable to communities that have received preventative chemotherapy in SAC or in SAC and adults, as well as those that have not received any. Our study indicates that it is possible to extrapolate PSAC prevalence levels from SAC prevalence, and to make a treatment decision on that basis.

Snail-Related Contributions from the Schistosomiasis Consortium for Operational Research and Evaluation Program Including Xenomonitoring, Focal Mollusciciding, Biological Control, and Modeling

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was created in 2008 to answer questions of importance to program managers working to reduce the burden of schistosomiasis in Africa. In the past, intermediate host snail monitoring and control was an important part of integrated schistosomiasis control. However, in Africa, efforts to control snails have declined dramatically over the last 30 years. A resurgence of interest in the control of snails has been prompted by the realization, backed by a World Health Assembly resolution (WHA65.21), that mass drug administration alone may be insufficient to achieve schistosomiasis elimination. SCORE has supported work on snail identification and mapping and investigated how xenomonitoring techniques can aid in the identification of infected snails and thereby identify potential transmission areas. Focal mollusciciding with niclosamide was undertaken in Zanzibar and Côte d'Ivoire as a part of elimination studies. Two studies involving biological control of snails were conducted: one explored the association of freshwater riverine prawns and snail hosts in Côte d'Ivoire and the other assessed the current distribution of Procambarus clarkii, the invasive Louisiana red swamp crayfish, in Kenya and its association with snail hosts and schistosomiasis transmission. SCORE also supported modeling studies on the importance of snail control in achieving elimination and a meta-analysis of the impact of molluscicide-based snail control programs on human schistosomiasis prevalence and incidence. SCORE's snail control studies contributed to increased investment in building capacity, and specimens collected during SCORE research deposited in the Schistosomiasis Collections at the Natural History Museum (SCAN) will provide a valuable resource for the years to come.

High prevalence of Schistosoma haematobium × Schistosoma bovis hybrids in schoolchildren in Côte d'Ivoire

Schistosomiasis is a neglected tropical disease, though it is highly prevalent in many parts of sub-Saharan Africa. While Schistosoma haematobium-bovis hybrids have been reported in West Africa, no data about Schistosoma hybrids in humans are available from Côte d'Ivoire. This study aimed to identify and quantify S. haematobium-bovis hybrids among schoolchildren in four localities of Côte d'Ivoire. Urine samples were collected and examined by filtration to detect Schistosoma eggs. Eggs were hatched and 503 miracidia were individually collected and stored on Whatman® FTA cards for molecular analysis. Individual miracidia were molecularly characterized by analysis of mitochondrial cox1 and nuclear internal transcribed spacer 2 (ITS 2) DNA regions. A mitochondrial cox1-based diagnostic polymerase chain reaction was performed on 459 miracidia, with 239 (52.1%) exhibiting the typical band for S. haematobium and 220 (47.9%) the S. bovis band. The cox1 and ITS 2 amplicons were Sanger sequenced from 40 randomly selected miracidia to confirm species and hybrids status. Among the 33 cox1 sequences analysed, we identified 15 S. haematobium sequences (45.5%) belonging to seven haplotypes and 18 S. bovis sequences (54.5%) belonging to 12 haplotypes. Of 40 ITS 2 sequences analysed, 31 (77.5%) were assigned to pure S. haematobium, four (10.0%) to pure S. bovis and five (12.5%) to S. haematobium-bovis hybrids. Our findings suggest that S. haematobium-bovis hybrids are common in Côte d'Ivoire. Hence, intense prospection of domestic and wild animals is warranted to determine whether zoonotic transmission occurs.

Prevalence and Risk Factors for Schistosomiasis among Schoolchildren in two Settings of Côte d'Ivoire

Schistosomiasis is a parasitic disease affecting more than 250 million people, primarily in sub-Saharan Africa. In Côte d’Ivoire both Schistosoma haematobium (causing urogenital schistosomiasis) and Schistosoma mansoni (causing intestinal schistosomiasis) co-exist. This study aimed to determine the prevalence of S. haematobium and S. mansoni and to identify risk factors among schoolchildren in the western and southern parts of Côte d’Ivoire. From January to April 2018, a cross-sectional study was carried out including 1187 schoolchildren aged 5–14 years. Urine samples were examined by a filtration method to identify and count S. haematobium eggs, while stool samples were subjected to duplicate Kato-Katz thick smears to quantify eggs of S.mansoni and soil-transmitted helminths. Data on sociodemographic, socioeconomic, and environmental factors were obtained using a pretested questionnaire. Multivariate logistic regression was employed to test for associations between variables. We found a prevalence of S. haematobium of 14.0% (166 of 1187 schoolchildren infected) and a prevalence of S. mansoni of 6.1% (66 of 1089 schoolchildren infected). In the southern part of Côte d’Ivoire, the prevalence of S. haematobium was 16.1% with a particularly high prevalence observed in Sikensi (35.6%), while S. mansoni was most prevalent in Agboville (11.2%). Swimming in open freshwater bodies was the main risk factor for S. haematobium infection (adjusted odds ratio (AOR) = 127.0, 95% confidence interval (CI): 25.0–634.0, p < 0.001). Fishing and washing clothes in open freshwater bodies were positively associated with S. haematobium and S. mansoni infection, respectively. Preventive chemotherapy using praziquantel should be combined with setting-specific information, education, and communication strategies in order to change children’s behavior, thus avoiding contact with unprotected open freshwater.

Prevalence, Intensity of Soil-Transmitted Helminths, and Factors Associated with Infection: Importance in Control Program with Ivermectin and Albendazole in Eastern Côte d'Ivoire

Evaluation of soil-transmitted helminths (STHs) and implementation of additional interventions are required in the region of a filariasis control program, given that antifilariasis drugs also have a beneficial effect on STHs. Thus, this study determines the extensive epidemiology of STHs to improve their successful control. Stool samples were analyzed using the Kato-Katz method. Chi-squared and Kruskal-Wallis tests were used to measure differences in infection rates and intensities, respectively, and logistic regression identified the risks of infection. The main intestinal helminths (A. lumbricoides, hookworm [N. americanus], S. mansoni, and T. trichiura) were found in the population. The overall prevalence of STHs was 19.5%. The prevalence of hookworm, the predominant species, ranged from 2% (n=6) to 28% (n=97). The overall prevalence of the other intestinal helminths was less than 6% (n=18). Intensity of hookworm was mostly light with a range from 1.6% (n=5) to 25.9% (n=90). However, the intensity of the species was significantly greater in Soribadougou compared to the other localities. Heavy infection was found in old children and adults but not in young children. Open defecation (OR=3.23, p≤0.05), dog/cat raising (OR=1.94, p≤0.05), farming (OR=14.10, p≤0.05), and irrigated culture (OR=3.23, p≤0.05) were positively associated with hookworm. It was observed that the participants missed the follow-up examinations due to trip (32.7%) or misunderstanding (15%) and lack of information (11.8%) of the purpose of the survey. Thus, to sustain the control of STHs, the MDA program should target the entire community and add education about the use of toilets, best practices of farming, and dog/cat raising.

Schistosomiasis mansoni in families of fishing workers of endemic area of Alagoas

Abstract Objective: To analyze the epidemiological and clinical aspects involved in the transmission and manifestation of schistosomiasis in a community of fishermen from the endemic area of Alagoas. Methods: Epidemiological, transversal, prospective, descriptive, quantitative study. The coproparasitological survey included 275 family units of fish workers and the epidemiological and clinical ones, those with a positive diagnosis for S. mansoni. Results: The prevalence of schistosomiasis was 13.9% (fishermen), 2.1% (shellfish) and 2.1% (family members). The occurrence of the infection varied according to gender, age, ethnicity and socioeconomic status. Exposure occurred near the home. Autochthonous and predominant low parasite burden, intestinal clinical presentation, abdominal pain and diarrhea were observed. There were no nutritional and pressure changes associated with parasitosis. Adherence to drug therapy and use of the schistosomicidal drug was feared. Conclusion: Fish workers are at high risk for contracting the disease with clinical hepatointestinal manifestation, which requires more intense health actions.

Pharmacokinetics of Praziquantel in Schistosoma mansoni- and Schistosoma haematobium-Infected School- and Preschool-Aged Children

There is a growing consensus to include preschool-aged children in preventive chemotherapy programs with praziquantel to improve schistosomiasis control. However, pharmacokinetic data, crucial to establish a safe and effective dose for this age group, are sparse. The objective of this study was to establish and compare the pharmacokinetic parameters of praziquantel in preschool- and school-aged children with schistosomiasis. Two pharmacokinetic trials in school- and preschool-aged children infected with Schistosoma mansoni or S. haematobium were conducted in Côte d'Ivoire. Dried blood spot samples were taken from 492 children at 10 time points following a single oral dose of 20, 40, or 60 mg/kg of body weight of praziquantel and analyzed using liquid chromatography-mass spectrometry. Noncompartmental analysis (NCA) was performed to obtain the pharmacokinetic parameters of R-praziquantel (RPZQ), S-praziquantel (SPZQ), and R-trans-4-hydroxy-praziquantel. No significant differences in pharmacokinetic parameters between species-specific infections were observed. While pharmacokinetic parameters differed significantly between age groups for S. mansoni, this trend was not observed with S. haematobium Neither the area under the curve (AUC) nor the maximal blood concentration (C_max) presented clear dose proportionality for R- and SPZQ. Logistic regression indicated a relationship between the RPZQ AUC and C_max and the probability of cure. Praziquantel is subject to complex metabolic processes following erratic absorption. While the results of NCA are a very informative base for a better understanding of the drug, a more targeted approach in the form of population modeling is needed to quantify the factors influencing metabolic processes and draw conclusions.

A Rapid Appraisal of Factors Influencing Praziquantel Treatment Compliance in Two Communities Endemic for Schistosomiasis in Côte d'Ivoire

Over the past decade, a significant reduction in the prevalence of schistosomiasis has been achieved, partially explained by the large-scale administration of praziquantel. Yet, the burden of schistosomiasis remains considerable, and factors influencing intervention coverage are important. This study aimed to deepen the understanding of low treatment coverage rates observed in two schistosomiasis-endemic villages in Côte d’Ivoire. The research was conducted in August 2015, in Moronou and Bigouin, two villages of Côte d’Ivoire that are endemic for Schistosoma haematobium and S. mansoni, respectively. After completion of a clinical trial, standard praziquantel treatment (single 40 mg/kg oral dose) was offered to all village inhabitants by community health workers using a house-to-house approach. Factors influencing treatment coverage were determined by a questionnaire survey, randomly selecting 405 individuals. The overall treatment coverage rate was only 47.6% (2730/5733) with considerable intervillage heterogeneity (27.7% in Bigouin (302/1091) versus 52.3% in Moronou (2428/4642)). Among the 200 individuals interviewed in Moronou, 50.0% were administered praziquantel, while only 19.5% of the 205 individuals interviewed in Bigouin received praziquantel. The main reasons for low treatment coverage were work-related (agricultural activities), the bitter taste of praziquantel and previous experiences with adverse events. The most suitable period for treatment campaigns was reported to be the dry season. More than three-quarter of the interviewees who had taken praziquantel (overall, 116/140; Moronou, 84/100; Bigouin, 32/40) declared that they would not participate in future treatments (p < 0.001). In order to enhance praziquantel treatment coverage, careful consideration should be given to attitudes and practices, such as prior or perceived adverse events and taste of praziquantel, and appropriate timing, harmonized with agricultural activities. Without such understanding, breaking the transmission of schistosomiasis remains a distant goal.

Efficacy and safety of ascending doses of praziquantel against Schistosoma haematobium infection in preschool-aged and school-aged children: a single-blind randomised controlled trial

BACKGROUND

Despite decades of experience with praziquantel treatment in school-aged children (SAC) and adults, we still face considerable knowledge gaps relevant to the successful treatment of preschool-aged children (PSAC). This study aimed to assess the efficacy and safety of escalating praziquantel dosages in PSAC infected with Schistosoma haematobium.

METHODS

We conducted a randomised, dose-finding trial in PSAC (2-5 years) and as comparator a cohort of SAC (6-15 years) infected with S. haematobium in Côte d'Ivoire. A total of 186 PSAC and 195 SAC were randomly assigned to 20, 40 or 60 mg/kg praziquantel or placebo. The nature of the dose-response relationship in terms of cure rate (CR) was the primary objective. Egg reduction rate (ERR) and tolerability were secondary outcomes. CRs and ERRs were assessed using triplicate urine filtration over 3 consecutive days. Available-case analysis was performed including all participants with primary endpoint data.

RESULTS

A total of 170 PSAC and 174 SAC received treatment. Almost 90% of PSAC and three quarters of SAC were lightly infected with S. haematobium. Follow-up data were available for 157 PSAC and 166 SAC. In PSAC, CRs of praziquantel were 85.7% (30/35), 78.0% (32/41) and 68.3% (28/41) at 20, 40 and 60 mg/kg and 47.5% (19/40) for placebo. In SAC, CRs were 10.8% for placebo (4/37), 55.6% for 20 mg/kg (25/45), 68.3% for 40 mg/kg (28/41) and 60.5% for 60 mg/kg (26/43). ERRs based on geometric means ranged between 96.5% (60 mg/kg) and 98.3% (20 mg/kg) in PSAC and between 97.6% (20 mg/kg and 60 mg/kg) and 98.6% (40 mg/kg) in SAC. Adverse events were mild and transient.

CONCLUSIONS

Praziquantel revealed dose-independent efficacy against light infections of S. haematobium. Over the dose range tested, praziquantel displayed a ceiling effect with the highest response for 20 mg/kg in PSAC. In SAC maximum efficacy was obtained with 40 mg/kg praziquantel. Further investigations are required in children with moderate to heavy infections.

TRIAL REGISTRATION

This trial is registered with International Standard Randomised Controlled Trial Number ISRCTN15280205 .

Risk factors for schistosomiasis in an urban area in northern Côte d'Ivoire

Background

Schistosomiasis is a water-based disease transmitted by trematodes belonging to the genus Schistosoma. The aim of this study was to assess the relationship between the prevalence of schistosomiasis and access to water, sanitation and hygiene (WASH) and environmental and socioeconomic factors in the city of Korhogo, northern Côte d'Ivoire.

Methods

A cross-sectional study including 728 randomly selected households was conducted in Korhogo in March 2015. The heads of the households were interviewed about access to WASH and environmental and socioeconomic factors. All children abed between 5 and 15 years living in the households were selected to provide stool and urine samples for parasitological diagnosis of Schistosoma mansoni and Schistosoma haematobium infection. The relationship between infection with S. mansoni and potential risk factors was analysed by a mixed logistic regression model with ‘household’ as a random factor. Likelihood ratio tests were used to identify factors that were significantly associated with a Schistosoma spp. infection.

Results

The overall prevalence of schistosomiasis among school-aged children in Korhogo was 1.9% (45/2341) composed of 0.3% (3/1248) S. haematobium and 3.5% (42/1202) S. mansoni. Due to the low prevalence of S. haematobium infection, risk factor analysis was limited to S. mansoni. Boys were 7.8 times more likely to be infected with S. mansoni than girls. Children between 10 and 15 years of age were 3.8 times more likely to be infected than their younger counterparts aged 5-10 years. Moreover, living in a house further away from a water access point (odds ratio [OR] = 0.29, 95% confidence interval [CI]: 0.13–0.70) and abstaining from swimming in open freshwater bodies (OR = 0.16, 95% CI: 0.04–0.56) were significantly associated with decreased odds of S. mansoni infection. The socioeconomic status did not appear to influence the prevalence of S. mansoni.

Conclusions

A strategy to reduce the incidence of schistosomiasis should focus on health education to change the behaviour of populations at risk and encourage communities to improve sanitation and infrastructure in order to reduce contact with surface water.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0431-6) contains supplementary material, which is available to authorized users.

Efficacy and safety of praziquantel in preschool-aged and school-aged children infected with Schistosoma mansoni: a randomised controlled, parallel-group, dose-ranging, phase 2 trial

Background

Praziquantel has been the drug of choice for schistosomiasis control for more than 40 years, yet surprisingly, the optimal dose for children younger than 4 years is not known. We aimed to assess the efficacy and safety of escalating praziquantel dosages in preschool-aged children (PSAC).

Methods

We did a randomised controlled, parallel-group, single-blind, dose-ranging, phase 2 trial in PSAC (2–5 years) and school-aged children (SAC; aged 6–15 years) as a comparator group in southern Côte d'Ivoire. Children were randomly assigned (1:1:1:1) to 20 mg/kg, 40 mg/kg, or 60 mg/kg praziquantel or placebo. Participants, investigators, and laboratory technicians were masked to group assignment, while the investigator providing treatment was aware of the treatment group. The primary objective was to estimate the nature of the dose–response relation in terms of cure rate using the Kato Katz technique. Dose–response curves were estimated using E_max models. Available case analysis was done including all participants with primary endpoint data. This trial is registered with International Standard Randomised Controlled Trial, number ISRCTN15280205.

Findings

Between Nov 11, 2014, and Feb 18, 2015, 660 PSAC and 225 SAC were assessed for eligibility; of whom 161 (24%) PSAC and 180 (80%) SAC had a detectable Schistosoma mansoni infection. 161 PSAC were randomly allocated of whom 154 received treatment: 42 were assigned to 20 mg/kg praziquantel, of whom 40 received treatment; 38 were assigned to 40 mg/kg praziquantel, of whom 38 received treatment; 41 were assigned to 60 mg/kg praziquantel, of whom 39 received treatment; and 40 were assigned to placebo, of whom 37 received placebo. 180 SAC were randomly allocated of whom 177 received treatment: 49 were assigned to 20 mg/kg praziquantel, of whom 47 received treatment; 46 were assigned to 40 mg/kg praziquantel, of whom 46 received treatment; 42 were assigned to 60 mg/kg praziquantel, of whom 42 received treatment; and 43 were assigned to placebo, of whom 43 received treatment. Follow-up (available-case) data were available for 143 PSAC and 174 SAC. In PSAC, the 20 mg/kg dose resulted in cure in 23 children (62%; 95% CI 44·8–77·5), 40 mg/kg in 26 children (72%; 54·8–85·8), 60 mg/kg in 25 children (71%; 53·7–85·4), and placebo in 13 children (37%; 21·5–55·1). In SAC, the 20 mg/kg dose resulted in cure in 14 children (30%; 95% CI 17·7–45·8), 40 mg/kg in 31 children (69%; 53·4–81·8), 60 mg/kg in 34 children (83%; 67·9–92·8), and placebo in five children (12%; 4·0–25·6). For both age groups, the number of adverse events was similar among the three praziquantel treatment groups, with fewer adverse events observed in the placebo groups. The most common adverse events in PSAC were diarrhoea (11 [9%] of 124) and stomach ache (ten [8%]) and in SAC were diarrhoea (50 [28%] of 177), stomach ache (66 [37%]), and vomiting (26 [15%]) 3 h post treatment. No serious adverse events were reported.

Interpretation

Praziquantel shows a flat dose-response and overall lower efficacy in PSAC compared with in SAC. In the absence of treatment alternatives, a single dose of praziquantel of 40 mg/kg, recommended by the WHO for S mansoni infections in SAC can be endorsed for PSAC in preventive chemotherapy programmes.

Funding

European Research Council.

Interrupting seasonal transmission of Schistosoma haematobium and control of soil-transmitted helminthiasis in northern and central Côte d'Ivoire: a SCORE study protocol

Background

To achieve a world free of schistosomiasis, the objective is to scale up control and elimination efforts in all endemic countries. Where interruption of transmission is considered feasible, countries are encouraged to implement a comprehensive intervention package, including preventive chemotherapy, information, education and communication (IEC), water, sanitation and hygiene (WASH), and snail control. In northern and central Côte d’Ivoire, transmission of Schistosoma haematobium is seasonal and elimination might be achieved. In a cluster-randomised trial, we will assess different treatment schemes to interrupt S. haematobium transmission and control soil-transmitted helminthiasis over a 3-year period. We will compare the impact of (i) arm A: annual mass drug administration (MDA) with praziquantel and albendazole before the peak schistosomiasis transmission season; (ii) arm B: annual MDA after the peak schistosomiasis transmission season; (iii) arm C: two yearly treatments before and after peak schistosomiasis transmission; and (iv) arm D: annual MDA before peak schistosomiasis transmission, coupled with chemical snail control using niclosamide.

Methods/design

The prevalence and intensity of S. haematobium and soil-transmitted helminth infections will be assessed using urine filtration and Kato-Katz thick smears, respectively, in six administrative regions in northern and central parts of Côte d’Ivoire. Once a year, urine and stool samples will be collected and examined from 50 children aged 5–8 years, 100 children aged 9–12 years and 50 adults aged 20–55 years in each of 60 selected villages. Changes in S. haematobium and soil-transmitted helminth prevalence and intensity will be assessed between years and stratified by intervention arm. In the 15 villages randomly assigned to intervention arm D, intermediate host snails will be collected three times per year, before niclosamide is applied to the selected freshwater bodies. The snail abundance and infection rates over time will allow drawing inference on the force of transmission.

Discussion

This cluster-randomised intervention trial will elucidate whether in an area with seasonal transmission, the four different treatment schemes can interrupt S. haematobium transmission and control soil-transmitted helminthiasis. Lessons learned will help to guide schistosomiasis control and elimination programmes elsewhere in Africa.

Trial registration

ISRCTNISRCTN10926858. Registered 21 December 2016. Retrospectively registered.

Estimating sensitivity of the Kato-Katz technique for the diagnosis of Schistosoma mansoni and hookworm in relation to infection intensity

The Kato-Katz technique is the most widely used diagnostic method in epidemiologic surveys and drug efficacy trials pertaining to intestinal schistosomiasis and soil-transmitted helminthiasis. However, the sensitivity of the technique is low, particularly for the detection of light-intensity helminth infections. Examination of multiple stool samples reduces the diagnostic error; yet, most studies rely on a single Kato-Katz thick smear, thus underestimating infection prevalence. We present a model which estimates the sensitivity of the Kato-Katz technique in Schistosoma mansoni and hookworm, as a function of infection intensity for repeated stool sampling and provide estimates of the age-dependent 'true' prevalence. We find that the sensitivity for S. mansoni diagnosis is dominated by missed light infections, which have a low probability to be diagnosed correctly even through repeated sampling. The overall sensitivity strongly depends on the mean infection intensity. In particular at an intensity of 100 eggs per gram of stool (EPG), we estimate a sensitivity of 50% and 80% for one and two samples, respectively. At an infection intensity of 300 EPG, we estimate a sensitivity of 62% for one sample and 90% for two samples. The sensitivity for hookworm diagnosis is dominated by day-to-day variation with typical values for one, two, three, and four samples equal to 50%, 75%, 85%, and 95%, respectively, while it is only weakly dependent on the mean infection intensity in the population. We recommend taking at least two samples and estimate the 'true' prevalence of S. mansoni considering the dependence of the sensitivity on the mean infection intensity and the 'true' hookworm prevalence by taking into account the sensitivity given in the current study.

Agreement among Four Prevalence Metrics for Urogenital Schistosomiasis in the Eastern Region of Ghana

Few studies assess agreement among Schistosoma haematobium eggs, measured hematuria, and self-reported metrics. We assessed agreement among four metrics at a single time point and analyzed the stability of infection across two time points with a single metric. We used data from the Eastern Region of Ghana and constructed logistic regression models. Girls reporting macrohematuria were 4.1 times more likely to have measured hematuria than girls not reporting macrohematuria (CI_95%: 2.1–7.9); girls who swim were 3.6 times more likely to have measured hematuria than nonswimmers (CI_95%: 1.6–7.9). For boys, neither self-reported metric was predictive. Girls with measured hematuria in 2010 were 3.3 times more likely to be positive in 2012 (CI_95%: 1.01–10.5), but boys showed no association. Boys with measured hematuria in 2008 were 6.0 times more likely to have measured hematuria in 2009 (CI_95%: 1.5–23.9) and those with eggs in urine in 2008 were 4.8 times more likely to have eggs in urine in 2009 (CI_95%: 1.2–18.8). For girls, measured hematuria in 2008 predicted a positive test in 2009 (OR = 2.8; CI_95%: 1.1–6.8), but egg status did not. Agreement between dipstick results and eggs suggests continued dipstick used is appropriate. Self-reported swimming should be further examined. For effective disease monitoring, we recommend annual dipstick testing.

Schistosomiasis Sustained Control Program in Ethnic Groups Around Ninefescha (Eastern Senegal)

Schistosomiasis is the second most significant parasitic disease in children in several African countries. For this purpose, the "Programme National de Lutte contre les Bilharzioses" (PNLB) was developed in partnership with the World Health Organization (WHO) to control this disease in Senegal. However, geographic isolation of Bedik ethnic groups challenged implementation of the key elements of the schistosomiasis program in eastern Senegal, and therefore, a hospital was established in Ninefescha to improve access to health care as well as laboratory support for this population. The program we have implemented from 2008 in partnership with the PNLB/WHO involved campaigns to 1) evaluate schistosomiasis prevalence in children of 53 villages around Ninefescha hospital, 2) perform a mass drug administration following the protocol established by the PNLB in school-aged children, 3) monitor annual prevalence, 4) implement health education campaigns, and 5) oversee the building of latrines. This campaign led to a drop in schistosomiasis prevalence but highlighted that sustainable schistosomiasis control by praziquantel treatment, awareness of the use of latrines, and inhabitants' voluntary commitment to the program are crucial to improve Schistosoma elimination. Moreover, this study revealed that preschool-aged children, for whom praziquantel was not recommended until 2014 in Senegal, constituted a significant reservoir for the parasite.

Schistosoma mansoni and soil-transmitted helminths among preschool-aged children in Chuahit, Dembia district, Northwest Ethiopia: prevalence, intensity of infection and associated risk factors

BACKGROUND

Intestinal schistosomiasis and soil-transmitted helminthiasis are the major public health problems globally. Compared with any other age group, pre-school aged children and school-aged children are the most exposed. There are few studies showing the burden of intestinal schistosomiasis, and soil-transmitted helminthiasis among pre-school aged children in Ethiopia. Hence, this study aimed to assess the prevalence of schistosoma mansoni and soil-transmitted helminths and associated risk factors among preschool aged children of Chuahit and surrounding Kebeles, Northwest Ethiopia.

METHODS

A community based cross sectional study was conducted from February 2 to March 27 2015. Four hundred one preschool-aged children were included in the study by using two stage cluster sampling technique. Pretested structured questionnaire was employed to collected data via face-to-face interview technique. A single stool specimen was collected, and a portion of the sample was processed by Kato Katz method.

RESULTS

Of the total children, 141 (35.2 %) harbored one or more intestinal helminthes. Schistosoma mansoni was found in 45 (11.2 %) of preschool age children. Ascaris lumbricoides was the predominant isolate, 77 (19.2 %) followed by S. mansoni, 45 (11.2 %). The least parasites isolated were Tania species, 2 (0.5 %). After adjusting for other variables, being mothers who did not have the habit of washing hands after toilet (AOR = 7.3, 95%CI: 2.97-17.95), being occupationally housewife mothers (AOR = 8.9, 95%CI: 2.27-25.4), using protected spring water as a main family source of water (AOR = 3.9, 95%CI: 1.2-12.3) and child habit of not wearing shoe (AOR = 1.91, 95%CI: 1.01-3.64) were significantly associated with high prevalence of soil-transmitted helminthiasis among preschool-age children in Chuahit.

CONCLUSION

The current study showed that relatively higher level of STH and S. mansoni among preschool-aged children in Chuahit. This finding calls for a need of public health education, promotion of women education and provision of safe water to reduce the burden of soil-transmitted intestinal helminthiasis and schistosomiaisis.

Comparison of Schistosoma mansoni Prevalence and Intensity of Infection, as Determined by the Circulating Cathodic Antigen Urine Assay or by the Kato-Katz Fecal Assay: A Systematic Review

The relationship between results from Kato-Katz (KK) fecal microscopy and urine-based point-of-care circulating cathodic antigen (POC-CCA) assays for Schistosoma mansoni infection remains a critical issue. This systematic literature review of 25 published papers compares prevalence of S. mansoni infection by KK with that by the POC-CCA assay. Nineteen published studies met our inclusion criteria for data extraction and analysis. Above a prevalence of 50% by KK, KK and POC-CCA results yielded essentially the same prevalence. Below 50% prevalence by KK, the prevalence by the POC-CCA assay was between 1.5- and 6-fold higher and increased as prevalence by KK decreased. Five of nine publications met inclusion criteria for extractable data on intensity of S. mansoni infection by KK assay and visual band density using the POC-CCA assay. A clear positive relationship exists between intensity by the KK and POC-CCA assays. This systematic review indicates that below 50% prevalence, the POC-CCA assay is much more sensitive than the KK assay. However, the existing data are inadequate to precisely define the relationship between POC-CCA and KK at lower levels of KK prevalence. More studies directly comparing the two assays in low-prevalence areas are essential to inform decision-making by national schistosomiasis control programs.

Epidemiology of Schistosomiasis and Usefulness of Indirect Diagnostic Tests in School-Age Children in Cubal, Central Angola

INTRODUCTION

Schistosomiasis remains a public health major problem and little is known in many areas, mainly in Sub-Saharan Africa.

OBJECTIVES

To assess the burden and risk factors of schistosomiasis and intestinal parasitic helminthes in the children of Cubal, Angola, and to compare different diagnostic approaches for urinary schistosomiasis under field conditions.

METHODS

A cross-sectional study was conducted. Urine and faeces samples of school children were microscopically studied. A random sample of children was obtained from an alphabetically arranged list of children, taking one of two children. Urine dipstick, colorimetric test and macrohaematuria were considered as indirect diagnostic methods and compared to direct urine examination. Possible risk factors for the infection were sex, age, distance to the river and previous treatment with praziquantel; the assessment was performed using Chi-square test.

RESULTS

A total of 785 (61.18%) children showed S. haematobium eggs in urine; children living within 500 meters from the river had a higher odds for infection: Odds ratio 1.97 (1.45-2.7 CI 95%); urine dipstick showed sensitivity of 96% and specificity of 61.3%, with a positive predictive value; colorimetric test showed sensitivity of 52.5%, specificity of 74.6% and a positive predictive value of 77%. Proteinuria was present in 653 (51.1%) children, being more frequent in children with S. haematobium in urine (75.2%); 32 of 191 stool samples (16%) showed the presence of other intestinal parasites and 8 (4%) for S. haematobium.

CONCLUSIONS

Prevalence of urinary schistosomiasis in our study area is much higher than the national average, considering it as a high-risk community. Proximity to a source of water was a risk factor for the infection. Indirect tests, as urine dipstick and colorimetric test, were useful tools for diagnosis, due to ease of use and low cost. Proteinuria was a common finding, probably showing an early structural damage due to schistosomiasis in this group of children.

Predictive Value of School-Aged Children's Schistosomiasis Prevalence and Egg Intensity for Other Age Groups in Western Kenya

World Health Organization recommendations for the timing and target population for mass drug administration (MDA) for schistosomiasis are based on the prevalence of infection in school children within a given community. In a large study comparing MDA approaches for Schistosoma mansoni control, we evaluated whether prevalence of infection and egg burdens in 9- to 12-year-old students reflected infection levels in young children and adults in the same community. Cross-sectional surveys of preadolescents (9-12 years old) were compared with those of first year students (5-8 years old) in 225 villages and adults (20-55 years old) in 150 villages along the Kenyan shores of Lake Victoria. Village schistosomiasis prevalence and intensity levels in preadolescents strongly correlated (P < 0.0001) with prevalence and infection intensity for other age groups in the community. Our findings suggest that S. mansoni prevalence and intensity among 9- to 12-year-olds are valid for community sampling purposes in mapping for MDAs.

Schistosoma mansoni among pre-school children in Musozi village, Ukerewe Island, North-Western-Tanzania: prevalence and associated risk factors

BACKGROUND

Recent evidence indicates that pre-school children (PSC) living in S. mansoni highly endemic areas are at similar risk of schistosomiasis infection and morbidity as their school aged siblings. Recognizing this fact, the World Health Organization (WHO) is considering including this age group in highly endemic areas in control programmes using mass drug administration (MDA). However, detailed epidemiological information on S. mansoni infection among PSC is lacking for many endemic areas, specifically in Tanzania. This study was conducted to determine the prevalence of S. mansoni infection and its associated risk factors among PSC in Ukerewe Island, North-Western Tanzania.

METHODS

This was a cross-sectional study, which studied 400 PSC aged 1-6 years. The Kato-Katz (K-K) technique and the point of care circulating cathodic antigen (CCA) immunodiagnostic test were used to diagnose S. mansoni infection in stool and urine samples respectively. A pre-tested questionnaire was used to collect demographic data and water contact behaviour of the children from their parents/guardians.

RESULTS

Based on the K-K technique, 44.4% (95% CI: 39.4-49.4) pre-school children were infected with S. mansoni and the overall geometric mean eggs per gram of faeces (GM-epg) was 110.6 epg with 38.2 and 14.7% having moderate and heavy intensity infections respectively. Based on the CCA, 80.1%, (95% CI: 76.0-84.0) were infected if a trace was considered positive, and 45.9%, (95% CI: 40.9-50.9), were infected if a trace was considered negative. Reported history of lake visits (AOR = 2.31, 95% CI: 1.06-5.01, P < 0.03) and the proximity to the lake shore (<500 m) (AOR = 2.09, 95% CI: 1.05-4.14, P < 0.03) were significantly associated with S. mansoni infection. Reported lake visit frequency (4-7 days/week) was associated with heavy intensities of S. mansoni infection (P < 0.00).

CONCLUSION

The prevalence of S. mansoni infection in the study population using K-K and CCA-trace-negative was moderate. The frequency of lake visits and the proximity to the lake shore were associated with the infection of S. mansoni and its intensity. These findings call for the need to include the PSC in MDA programmes, public health education and provision of safe water for bathing.

Risk profiling of schistosomiasis using remote sensing: approaches, challenges and outlook

BACKGROUND

Schistosomiasis is a water-based disease that affects an estimated 250 million people, mainly in sub-Saharan Africa. The transmission of schistosomiasis is spatially and temporally restricted to freshwater bodies that contain schistosome cercariae released from specific snails that act as intermediate hosts. Our objective was to assess the contribution of remote sensing applications and to identify remaining challenges in its optimal application for schistosomiasis risk profiling in order to support public health authorities to better target control interventions.

METHODS

We reviewed the literature (i) to deepen our understanding of the ecology and the epidemiology of schistosomiasis, placing particular emphasis on remote sensing; and (ii) to fill an identified gap, namely interdisciplinary research that bridges different strands of scientific inquiry to enhance spatially explicit risk profiling. As a first step, we reviewed key factors that govern schistosomiasis risk. Secondly, we examined remote sensing data and variables that have been used for risk profiling of schistosomiasis. Thirdly, the linkage between the ecological consequence of environmental conditions and the respective measure of remote sensing data were synthesised.

RESULTS

We found that the potential of remote sensing data for spatial risk profiling of schistosomiasis is - in principle - far greater than explored thus far. Importantly though, the application of remote sensing data requires a tailored approach that must be optimised by selecting specific remote sensing variables, considering the appropriate scale of observation and modelling within ecozones. Interestingly, prior studies that linked prevalence of Schistosoma infection to remotely sensed data did not reflect that there is a spatial gap between the parasite and intermediate host snail habitats where disease transmission occurs, and the location (community or school) where prevalence measures are usually derived from.

CONCLUSIONS

Our findings imply that the potential of remote sensing data for risk profiling of schistosomiasis and other neglected tropical diseases has yet to be fully exploited.

Schistosoma mansoni in schoolchildren in a Madagascan highland school assessed by PCR and sedimentation microscopy and Bayesian estimation of sensitivities and specificities

Madagascar is an endemic area for schistosomiasis, but recent prevalence data are scarce. We investigated stool samples of 410 children aged 4-18 years from a combined primary and secondary school in a Madagascan highland village near Ambositra in order to assess the prevalence of Schistosoma mansoni using microscopy and real-time polymerase chain reaction (PCR). A high prevalence of S. mansoni of 77.1% was detected by PCR, while only 15.2% of microscopic examinations of sedimentation-enriched stools were positive. We estimated the sensitivity and specificity of stool sedimentation microscopy (19.7% and 98.8%) and of PCR (98.9% and 89.3%) using a Bayesian approach for two dependant tests in one population without a reference standard. Our Bayesian posterior estimate of the prevalence is 80.2%. Simple sedimentation technique misses about 4/5 of all PCR-confirmed infections and is insufficient to determine the prevalence of S. mansoni. A survey comparing PCR with a classical standard technique (KatoKatz) is desirable.

Evaluation of portable microscopic devices for the diagnosis of Schistosoma and soil-transmitted helminth infection

The diagnosis of parasitic worm (helminth) infections requires specialized laboratory settings, but most affected individuals reside in locations without access to such facilities. We tested two portable microscopic devices for the diagnosis of helminth infections in a cross-sectional survey in rural Côte d'Ivoire. We examined 164 stool samples under a light microscope and then re-examined with a commercial portable light microscope and an experimental mobile phone microscope for the diagnosis of Schistosoma mansoni and soil-transmitted helminths. Additionally, 180 filtered urine samples were examined by standard microscopy and compared with the portable light microscope for detection of Schistosoma haematobium eggs. Conventional microscopy was considered the diagnostic reference standard. For S. mansoni, S. haematobium and Trichuris trichiura, the portable light microscope showed sensitivities of 84·8%, 78·6% and 81·5%, respectively, and specificities of 85·7%, 91·0% and 93·0%, respectively. For S. mansoni and T. trichiura, we found sensitivities for the mobile phone microscope of 68·2% and 30·8%, respectively, and specificities of 64·3% and 71·0%, respectively. We conclude that the portable light microscope has sufficient diagnostic yield for Schistosoma and T. trichiura infections, while the mobile phone microscope has only modest sensitivity in its current experimental set-up. Development of portable diagnostic technologies that can be used at point-of-sample collection will enhance diagnostic coverage in clinical and epidemiological settings.

The epidemiology of polyparasitism and implications for morbidity in two rural communities of Côte d'Ivoire

Background

Polyparasitism is still widespread in rural communities of the developing world. However, the epidemiology of polyparasitism and implications for morbidity are poorly understood. We studied patterns of multiple species parasite infection in two rural communities of Côte d’Ivoire, including associations and interactions between infection, clinical indicators and self-reported morbidity.

Methods

Between August and September 2011, two purposely selected rural communities in southern Côte d’Ivoire were screened for helminth, intestinal protozoa and Plasmodium infection, using a suite of quality-controlled diagnostic methods. Additionally, participants were examined clinically and we measured haemoglobin level, height, weight and mid-upper arm circumference to determine nutritional status. An anamnestic questionnaire was administered to assess people’s recent history of diseases and symptoms, while a household questionnaire was administered to heads of household to collect socioeconomic data. Multivariate logistic regression models were applied for assessment of possible associations between parasitic (co-)infections and morbidity outcomes.

Results

912/1,095 (83.3%) study participants had complete parasitological data and 852 individuals were considered for in-depth analysis. The rate of polyparasitism was high, with Plasmodium falciparum diagnosed as the predominant species, followed by Schistosoma haematobium, Schistosoma mansoni and hookworm. There were considerable differences in polyparasitic infection profiles among the two settings. Clinical morbidity such as anaemia, splenomegaly and malnutrition was mainly found in young age groups, while in adults, self-reported morbidity dominated. High parasitaemia of P. falciparum was significantly associated with several clinical manifestations such as anaemia, splenomegaly and fever, while light-intensity helminth infections seemed to have beneficial effects, particularly for co-infected individuals.

Conclusions

Clinical morbidity is disturbingly high in young age groups in rural communities of Côte d’Ivoire and mainly related to very high P. falciparum endemicity. Interactions between helminth infections and P. falciparum burden (parasitaemia and clinical morbidity) are evident and must be taken into account to design future interventions.

Schistosomiasis research in Africa: how the CONTRAST alliance made it happen

In May 2012, the World Health Assembly passed resolution WHA 65.21, calling upon member states to intensify schistosomiasis control and, wherever possible, to attempt transmission interruption and initiate interventions towards local elimination. It is now clear that CONTRAST--a multidisciplinary alliance to optimize schistosomiasis control and transmission surveillance in sub-Saharan Africa--was ahead of the game. Indeed, launched in October 2006, this 4-year project funded by the European Commission made important contributions for sustainable schistosomiasis control in the selected African countries through innovation, validation and application of new tools and locally adapted intervention strategies complementary to preventive chemotherapy. Moreover, CONTRAST articulated a research agenda for schistosomiasis elimination, framed by 10 key questions. Here, we provide a rationale for CONTRAST and discuss its overarching goal, the interrelated objectives, establishment and running of a research node network across Africa, partnership configuration and modus operandi of the project. A collection of 25 articles is presented that are grouped into five main themes: molecular, biological, spatial, social and cross-cutting issues pertaining to the epidemiology and control of schistosomiasis. We summarize key achievements made by CONTRAST, many of which are featured in this special issue of Acta Tropica. Together with an independent view put forth by an eminent schistosomiasis researcher, the current piece provides an umbrella for the 25-article collection, including current gaps and remaining research needs. Finally, post-CONTRAST initiatives are discussed and a speculative viewpoint is given on how schistosomiasis control/elimination will have evolved over the next several years.

Diagnosis and treatment of schistosomiasis in children in the era of intensified control

In the current era of intensified and integrated control against schistosomiasis and other neglected tropical diseases, there is a need to carefully rethink and take into consideration disease-specific issues pertaining to the diagnosis, prevention, control and local elimination. Here, we present a comprehensive overview about schistosomiasis including recent trends in the number of people treated with praziquantel and the latest developments in diagnosis and control. Particular emphasis is placed on children. Identified research needs are offered for consideration; namely, expanding our knowledge about schistosomiasis in preschool-aged children, assessing and quantifying the impact of schistosomiasis on infectious and noncommunicable diseases, developing new antischistosomal drugs and child-friendly formulations, designing and implementing setting-specific control packages and developing highly sensitive, but simple diagnostic tools that are able to detect very light infections in young children and in people living in areas targeted for schistosomiasis elimination.