Comparison of community-wide, integrated mass drug administration strategies for schistosomiasis and soil-transmitted helminthiasis: a cost-eff ectiveness modelling study

Background More than 1·5 billion people are aff ected by schistosomiasis or soil-transmitted helminthiasis. WHO’s recommendations for mass drug administration (MDA) against these parasitic infections emphasise treatment of school-aged children, using separate treatment guidelines for these two helminthiases groups. We aimed to evaluate the cost-eff ectiveness of expanding integrated MDA to the entire community in four settings in Côte d’Ivoire. Methods We extended previously published, dynamic, age-structured models of helminthiases transmission to simulate costs and disability averted with integrated MDA (of praziquantel and albendazole) for schistosomiasis and soil-transmitted helminthiasis. We calibrated the model to data for prevalence and intensity of species-specifi c helminth infection from surveys undertaken in four communities in Côte d’Ivoire between March, 1997, and September, 2010. We simulated a 15-year treatment programme with 75% coverage in only school-aged children; school-aged children and preschool-aged children; adults; and the entire community. Treatment costs were estimated at US$0·74 for school-aged children and$1·74 for preschool-aged children and adults. The incremental costeff ectiveness ratio (ICER) was calculated in 2014 US dollars per disability-adjusted life-year (DALY) averted. Findings Expanded community-wide treatment was highly cost eff ective compared with treatment of only school-aged children (ICER $167 per DALY averted) and WHO guidelines (ICER$127 per DALY averted), and remained highly cost eff ective even if treatment costs for preschool-aged children and adults were ten times greater than those for school-aged children. Community-wide treatment remained highly cost eff ective even when elimination of helminth infections was not achieved. These fi ndings were robust across the four diverse communities in Côte d’Ivoire, only one of which would have received annual MDA for both schistosomiasis and soil-transmitted helminthiasis under the latest WHO guidelines. Treatment every 6 months was also highly cost eff ective in three out of four communities. Interpretation Integrated, community-wide MDA programmes for schistosomiasis and soil-transmitted helminthiasis can be highly cost eff ective, even in communities with low disease burden in any helminth group. These results support an urgent need to re-evaluate current global guidelines for helminthiases control programmes to include community-wide treatment, increased treatment frequency, and consideration for lowered prevalence thresholds for integrated treatment

Are schoolchildren less infected if they have good knowledge about parasitic worms? A case study from rural Côte d'Ivoire

Background: Parasitic worms (helminths) are common infections in low- and middle-income countries. For most helminth species, school-aged children are at highest risk of infection and morbidity, such as impaired cognitive and physical development. Preventive chemotherapy is the current mainstay for helminthiases control. Sanitation improvement and hygiene-related education are important complementary strategies, which act by altering children’s behaviour. However, little is known about the effect of improved knowledge on the risk of helminth infection. The aim of this study was to assess the potential influence of knowledge that children acquired at home or in school, without any specific health education intervention, on helminth infections. Methods: In May 2014, we conducted a cross-sectional survey in western Côte d’Ivoire. A total of 2498 children, aged 9-12 years, were subjected to three consecutive stool examinations using duplicate Kato-Katz thick smears to determine infections with soil-transmitted helminths and Schistosoma mansoni. Additionally, children were interviewed to assess their knowledge about helminth infections. Four knowledge scores were constructed by factor analysis; one, reflecting general knowledge about helminths and three manifesting helminth species-specific knowledge. The effect of general and specific knowledge on children’s helminth infection status was determined using meta-analysis. Results: Children who scored high in the hookworm-specific knowledge were less likely to be infected with hookworm but no association was found for the other helminth species. Moreover, greater general knowledge was not associated with lower odds of being infected with any helminth species. Most of the children interviewed believed that the effect of preventive chemotherapy is permanent, and hence, re-treatment is not necessary. Conclusions: Specific knowledge about different types of helminths might not suffice to induce behavioural change which in turn reduces infection and reinfection with helminths. Health education interventions should strive to strengthen the perception of risk and to clarify the true benefit of preventive chemotherapy.publishersversionpublishe

Epidemiology of intestinal parasite infections in three departments of south-central Côte d’Ivoire before the implementation of a cluster-randomised trial

Hundreds of millions of people are infected with helminths and intestinal protozoa, particularly children in low- and middle-income countries. Preventive chemotherapy is the main strategy to control helminthiases. However, rapid re-infection occurs in settings where there is a lack of clean water, sanitation and hygiene. In August and September 2014, we conducted a cross-sectional epidemiological survey in 56 communities of three departments of south-central Côte d’Ivoire. Study participants were invited to provide stool and urine samples. Stool samples were examined for helminth and intestinal protozoa infections using the Kato-Katz technique and a formalin-ether concentration method. Urine samples were subjected to a filtration method for the diagnosis of Schistosoma haematobium. Information on sociodemographic characteristics, knowledge, attitude, practices and beliefs with regard to hygiene, sanitation and intestinal parasitic diseases were collected using a questionnaire administered to household heads. Multivariable logistic regression models were employed to analyse associations between parasite infections and risk factors. Overall, 4,305 participants had complete parasitological and questionnaire data. Hookworm was the predominant helminth species (21.2%), while Ascaris lumbricoides, Trichuris trichiura, Schistosoma mansoni and S. haematobium showed prevalences below 10%. Infections with pathogenic intestinal protozoa (e.g. Entamoeba histolytica/E. dispar and Giardia intestinalis) were similarly prevalent in the three departments. Hookworm infection was associated with open defecation and participants' age and sex. Entamoeba coli infection was negatively associated with the use of tap water at home (odds ratio (OR) = 0.66; p = 0.032). Disposal of garbage in close proximity to people’s home was positively associated with G. intestinalis (OR = 1.30; p = 0.015). Taken together, helminth and intestinal protozoa infections affected a considerable proportion of rural dwellers in south-central Côte d’Ivoire at the onset of a cluster-randomised intervention trial. Our results will serve as baseline to monitor the effect of a package of interventions, including preventive chemotherapy, sanitation and health education on re-infection with helminths and intestinal protozoa

Intestinal parasitic infections in schoolchildren in different settings of Côte d'Ivoire : effect of diagnostic approach and implications for control

BACKGROUND: Social-ecological systems govern parasitic infections in humans. Within the frame of assessing the accuracy of a rapid diagnostic test for Schistosoma mansoni in Cote d'Ivoire, three different endemicity settings had to be identified and schoolchildren's intestinal parasitic infection profiles were characterized. METHODS: In September 2010, a rapid screening was conducted in 11 schools in the Azaguie district, south Cote d'Ivoire. In each school, 25 children were examined for S. mansoni and S. haematobium. Based on predefined schistosome endemicity levels, three settings were selected, where schoolchildren aged 8-12 years were asked to provide three stool and three urine samples for an in-depth appraisal of parasitic infections. Triplicate Kato-Katz thick smears were prepared from each stool sample for S. mansoni and soil-transmitted helminth diagnosis, whereas urine samples were subjected to a filtration method for S. haematobium diagnosis. Additionally, a formol-ether concentration method was employed on one stool sample for the diagnosis of helminths and intestinal protozoa. Multivariable logistic regression models were employed to analyse associations between schoolchildren's parasitic infections, age, sex and study setting. RESULTS: The prevalences of S. mansoni and S. haematobium infections in the initial screening ranged from nil to 88% and from nil to 56%, respectively. The rapid screening in the three selected areas revealed prevalences of S. mansoni of 16%, 33% and 78%. Based on a more rigorous diagnostic approach, the respective prevalences increased to 92%, 53% and 33%. S. haematobium prevalences were 0.8%, 4% and 65%. Prevalence and intensity of Schistosoma spp., soil-transmitted helminths and intestinal protozoan infections showed setting-specific patterns. Infections with two or more species concurrently were most common in the rural setting (84%), followed by the peri-urban (28.3%) and urban setting (18.2%). CONCLUSIONS: More sensitive diagnostic tools or rigorous sampling approaches are needed to select endemicity settings with high fidelity. The observed small-scale heterogeneity of helminths and intestinal protozoan infections has important implications for contro

A Bayesian approach to estimate the age-specific prevalence of Schistosoma mansoni and implications for schistosomiasis control

Models that accurately estimate the age-specific infection prevalence of Schistosoma mansoni can be useful for schistosomiasis control programmes, particularly with regard to whether mass drug administration or selected treatment should be employed. We developed a Bayesian formulation of an immigration-death model that has been previously proposed, which used maximum likelihood inference for estimating the age-specific S. mansoni prevalence in a dataset from Egypt. For comparative purposes, we first applied the Bayesian formulation of the immigration-death model to the dataset from Egypt. We further analysed data obtained from a cross-sectional parasitological survey that determined the infection prevalence of S. mansoni among 447 individuals in a village in Côte d’Ivoire. Three consecutive stool samples were collected from each participant and analysed by the Kato-Katz technique. In the Côte d’Ivoire study, the observed S. mansoni infection prevalence was 41.6% and varied with age. The immigration-death model was able to correctly predict 50% of the observed age group-specific point prevalences. The model presented here can be utilized to estimate S. mansoni community infection prevalences, which in turn helps in the strategic planning of schistosomiasis control

Variabilité de la compatibilité entre Schistosoma Haematobium et ses hôtes potentiels dans la zone préforestière de Côte d’Ivoire : Implications épidémiologiques

Objectif : Caractériser les populations de Schistosoma Haematobium de la zone préforestière du centre de la Côte d’Ivoire par le marqueur de  compatibilité mollusque-parasite et estimer l’implication des populations de schistosomes dans la divergence épidémiologique de la bilharziose urinaire.Méthodologie et résultats : Quatre populations naturelles de S. haematobium ont été confrontées aux populations de première génération de Bulinus globosus (B. globosus) et Bulinus truncatus (B. truncatus)issues de l’aire d’étude. Cinq miracidiums ont servit à infester chaque jeune mollusque. Des combinaisons homopatriques et allopatriques ont été réalisées. La compatibilité mollusque-schistosome et l’implicationépidémiologique ont été appréciées par le taux de réussite à l’infestation (TRI). Au total 2638 Bulinus truncatus et 778 B. globosus ont été infestés. Trois variantes de S. haematobium inféodées à leurs mollusques hôtes ontété identifiées. Il s’agit des variantes dites « Truncatus », « Globosus » et d’une variante hybride. Les variantes « Truncatus » et « Hybride » sont susceptibles de propager la maladie dans l’aire d’étude et même au-delà.Conclusion et application des résultats : Notre étude a permis d’appréhender la variabilité génétique naturelle de la compatibilité entre Schistosoma Haematobium et ses hôtes potentiels. Ces trois populations de S. haematobium pourraient induire une divergence épidémiologique, elle-même source de complexité de la lutte contre la bilharziose urinaire. La lutte contre la bilharziose urinaire devra être envisagée au-delà des localités d’étude et se faire selon les systèmes écoépidémiologiques écologiques et épidémiologiques.. Au regard de nos résultats, il est recommandé des actions de lutte régulières dans les foyers de grand barrage où la souche parasitaire semble être susceptible à toutes les populations de Bulinus truncatus.Mots clés : Schistosoma haematobium, Bulinus globosus, Bulinus truncatus, compatibilité, Côte d’Ivoire Variability of compatibility between Schistosoma Haematobium and its potential hosts in preforest area of Ivory Coast: epidemiological implicationsObjective: To characterize Schistosoma haematobium’s populations of south-centralarea of Ivory Coast by the compatibility parasite-snail marker and estimate the involvement of schistosome populations in  epidemiological divergence of urinary schistosomiasis.Methodology and Results : Four natural populations of S. haematobium were compared with first-generation populations of Bulinus globosus (B. globosus) and Bulinus truncatus (B. truncatus) from the study area. Five miracidia served to infest every young snail. Homopatric and allopatric combinations were performed. The snail-schistosome compatibility and epidemiological involvement were assessed by the success rate of infestation (SRI). In total 2638 Bulinus truncatus and 778 B. globosus were infested. Three variants of S. haematobium subservient to their snail hosts were identified. There are called "Truncatus", "globosus" variants and a hybrid variant. The "Truncatus" and "hybrid" variants are likely to spread the disease in the study area and even beyond.Conclusion and application of results: This study helped us understand the natural genetic variability of the compatibility between Schistosoma Haematobium and potential hosts.. The fight against urinary schistosomiasis should be considered beyond the study areas. In light of these results, we recommend regular control activities in the large dam from homes where the parasite strain appears to be susceptible to all populations of Bulinus truncatus.Keys words: Schistosoma haematobium, Bulinus globosus, Bulinus truncatus, compatibility, Ivory Coast

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