Nana Diakité - Academia.edu (original) (raw)

Papers by Nana Diakité

BMC Zoology

Background Control of intermediate host snails using molluscicides for the control and/or elimina... more Background Control of intermediate host snails using molluscicides for the control and/or elimination of schistosomiasis is a strategy in line with WHO recommendations. Niclosamide is the main chemical molluscicide recommended by WHO. However, except the immediate killing of the snail, the extent of the impact of the molluscicide application on the evolution of snail life-history traits, in relation to recolonization of treated sites is not well known. This study aimed to characterize the spatial variation of life-history traits of populations of the freshwater snail Bulinus truncatus, in relation to niclosamide spraying in the field. From 2016 to 2018, we conducted a trial, using niclosamide to control the intermediate host snails for interrupting the seasonal transmission of urinary schistosomiasis in northern and central Côte d’Ivoire. Five villages (sites) were considered, including three test and two control villages. In the test villages, the molluscicide was sprayed in habita...

Additional file 1: Table S1: Correlations between traits at first reproduction in G1 individuals ... more Additional file 1: Table S1: Correlations between traits at first reproduction in G1 individuals from natural Bulinus truncatus populations according to the region and the treatment status. Table S2: Correlation coefficients for repeated measures between traits at early and late stages for the two study regions and the two treatment statutes. Table S3: Variation of first reproduction parameters of the Bulinus truncatus populations collected before and after niclosamide application in the Linguebo test village.

Background Accurate identification of schistosome species infecting intermediate host snails is i... more Background Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d'Ivoire and confirmed the presence of interspecific hybrid schistosomes. Methods Between June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d'Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification. Results Overall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii w...

Additional file 1: Table S1. Snail collection and schistosome infection data. N = North, C = Cent... more Additional file 1: Table S1. Snail collection and schistosome infection data. N = North, C = Central. Snail identification is based on shell morphology, except for the positive snails that were molecularly identified.

Background: Control of intermediate host snails using molluscicides for the control and/or elimin... more Background: Control of intermediate host snails using molluscicides for the control and/or elimination of schistosomiasis is strategy in the line with WHO recommendations. Niclosamide is the main chemical molluscicide recognized by WHO. However, the extent of the application of molluscicide outside the immediate killing of the snail such as the impact on the evolution of life-history traits; in relation to recolonization of treated sites is less or not known. This study aimed to characterize the spatial variation of life-history traits in Bulinus truncatus populations in north and central Côte d’Ivoire, in relation to niclosamide spraying in the field.From 2016 to 2018, we conducted a trial to control the intermediate host snails for interrupting seasonal transmission urinary schistosomiasis in northern and central Côte d’Ivoire, using niclosamide. The molluscicide was sprayed three times per year in habitats harboring the freshwater snail B. truncatus. Snails were collected before ...

International Journal of Innovation and Applied Studies, 2015

Presumptive diagnosis of malaria remains a common practice in several health facilities in C

PLOS Neglected Tropical Diseases, 2021

Background Preventive chemotherapy using praziquantel is the mainstay for schistosomiasis control... more Background Preventive chemotherapy using praziquantel is the mainstay for schistosomiasis control. However, there is little evidence on what is supposed to be the most effective school-based treatment strategy to sustain morbidity control. The aim of this study was to compare differences in Schistosoma mansoni prevalence and infection intensity between three different schedules of school-based preventive chemotherapy in an area with moderate prevalence of S. mansoni in Côte d’Ivoire. Methodology Seventy-five schools were randomly assigned to one of three intervention arms: (i) annual school-based preventive chemotherapy with praziquantel (40 mg/kg) over four years; (ii) praziquantel treatment only in the first two years, followed by two years whithout treatment; and (iii) praziquantel treatment in years 1 and 3 without treatment in-between. Cross-sectional parasitologic surveys were carried out prior to each round of preventive chemotherapy. The difference in S. mansoni prevalence a...

Tropical Medicine and Infectious Disease, 2021

In order to assess the impact of different control strategies against Schistosoma haematobium in ... more In order to assess the impact of different control strategies against Schistosoma haematobium in seasonal transmission foci in Côte d’Ivoire, a three-year cluster randomized trial was implemented. The decrease in S. haematobium prevalence among children aged 9−12 years was the primary outcome. In the first step, an eligibility survey was conducted, subjecting 50 children aged 13−14 years to a single urine filtration. Sixty-four villages with a prevalence of S. haematobium of ≥4% were selected and randomly assigned to four intervention arms consisting of annual mass drug administration (MDA) before (arm 1) and after (arm 2) the peak transmission, biannual treatment with praziquantel before and after the peak transmission season (arm 3), and annual MDA before the peak transmission season, coupled with focal chemical snail control using molluscicides (arm 4). At baseline, we observed a prevalence of 24.8%, 10.1%, 13.9%, and 15.9% in study arms 1, 2, 3, and 4, respectively. One year aft...

Frontiers in Tropical Diseases, 2021

IntroductionTraditionallySchistosoma mansoniinfection is diagnosed by the Kato-Katz method. Thick... more IntroductionTraditionallySchistosoma mansoniinfection 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.MethodsPOC-CCA was used to pre-screen forS. mansoniinfection. Children with positive results were tested by the Kato-Katz method, and those with positive Kato-Katz results (>1 egg/1 occurrence) were enrolled. Participants (N=444) were treat...

Clinical Infectious Diseases, 2021

Background Annual mass drug administration (MDA) using praziquantel is the cornerstone of schisto... more Background Annual mass drug administration (MDA) using praziquantel is the cornerstone of schistosomiasis morbidity control but is not sufficient to interrupt transmission. We implemented a cluster-randomized trial to compare the effectiveness of 4 different intervention packages to interrupt transmission of Schistosoma haematobium in a seasonal transmission setting of Côte d’Ivoire. Methods Sixty-four localities with a S. haematobium prevalence in school children aged 13–14 years above 4% were randomly assigned to 1 of 4 intervention arms over a 3-year period: (1) the current standard strategy consisting of annual MDA before peak of transmission, (2) annual MDA after peak of transmission, (3) biannual MDA, and (4) standard MDA combined with snail control. The primary outcome was prevalence and intensity of S. haematobium infection in children aged 9–12 years 1 year after the final intervention, using urine filtration performed by experienced microscopists. Results By study end, we ...

Journal of Applied Biosciences, 2021

Objectif : Identifier les espèces Schistosoma haematobium, S. bovis et leurs hybrides et, évaluer... more Objectif : Identifier les espèces Schistosoma haematobium, S. bovis et leurs hybrides et, évaluer la compatibilité des schistosomes avec les mollusques hôtes intermédiaires et la souris blanche (Mus musculus albinos), hôte définitif, en infestation expérimentale. Méthodologie et résultats : Des schistosomes ont été obtenus à partir de bulins infestés naturellement ou expérimentalement avec des miracidiums provenant des urines de l’homme. Ils ont permis d’étudier la compatibilité de quatre populations de Bulinus truncatus avec deux souches du groupe S. haematobium. La chronobiologie cercarienne a été étudiée à partir de quatre tranches horaires : 6-10h, 10-12h, 12-15h et 15- 18h. Des souris blanches infestées expérimentalement, ont été perfusées pour dénombrer les vers adultes. Une meilleure compatibilité schistosome-mollusque a été observée au niveau des infestations sympatriques. Le pic d’émergence cercarienne pour les mollusques naturellement infestés a été observé entre 6-10h, 10...

The American Journal of Tropical Medicine and Hygiene, 2020

As part of its diverse portfolio, the Schistosomiasis Consortium for Operational Research and Eva... more As part of its diverse portfolio, the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) included two cluster-randomized trials evaluating interventions that could potentially lead to interruption of schistosomiasis transmission (elimination) in areas of Africa with low prevalence and intensity of infection. These studies, conducted in Zanzibar and Côte d'Ivoire, demonstrated that multiyear mass drug administration (MDA) with praziquantel failed to interrupt the transmission of urogenital schistosomiasis, even when provided biannually and/or supplemented by small-scale implementation of additional interventions. Other SCORE activities related to elimination included a feasibility and acceptability assessment of test-treat-track-test-treat (T5) strategies and mathematical modeling. Future evaluations of interventions to eliminate schistosomiasis should recognize the difficulties inherent in conducting randomized controlled trials on elimination and in measuring small changes where baseline prevalence is low. Highly sensitive and specific diagnostic tests for use in very low-prevalence areas for schistosomiasis are not routinely available, which complicates accurate measurement of infection rates and assessment of changes resulting from interventions in these settings. Although not encountered in these two studies, as prevalence and intensity decrease, political and community commitment to population-wide MDA may decrease. Because of this potential problem, SCORE developed and funded the T5 strategy implemented in Egypt, Kenya, and Tanzania. It is likely that focal MDA campaigns, along with more targeted approaches, including a T5 strategy and snail control, will need to be supplemented with the provision of clean water and sanitation and behavior change communications to achieve interruption of schistosome transmission.

The American Journal of Tropical Medicine and Hygiene, 2020

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was created in 200... more 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.

BMC Public Health, 2018

Background: Parasitic worms (helminths) are common infections in low-and middle-income countries.... more 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.

Bulletin of Entomological Research, 2017

Since 2008, several outbreaks of yellow fever and dengue occurred in Abidjan, the economic capita... more Since 2008, several outbreaks of yellow fever and dengue occurred in Abidjan, the economic capital of Côte d'Ivoire. A better knowledge of the biology of Aedes aegypti populations, the main vector of yellow fever and dengue viruses, is necessary to tailor vector control strategies implemented in the city. This study was designed to determine some biological parameters, occurring during the life cycle of two morphological phenotypes of Ae. aegypti larvae. Mosquitoes were sampled in a suburb of Abidjan (Treichville) using the WHO layer-traps technique. Biological parameters were studied in laboratory under standard conditions of temperature (27°C ± 2°C) and relative humidity (80% ± 10%). Our results indicated that the mean eggs laid by females from ‘brown larvae’ (BL) (85.95, 95% confidence interval (CI 95%) 78.87–93.02) was higher than those from ‘white larvae’ (WL) (64.40%, CI 95% 55.27–73.54). The gonotrophic cycle was 3 and 4 days in females from BL and WL, respectively. The o...

Parasitology, 2018

The current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziq... more The current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziquantel. However, reinfection may occur rapidly in the absence of complementary interventions. Recent studies from Senegal suggest that predatory prawns might feed on intermediate host snails and thus impact on schistosomiasis transmission. We designed a study with four repeated cross-sectional surveys pertaining to prawns and snails, coupled with a single cross-sectional parasitological survey among humans. We assessed for potential associations between the presence/density of prawns and snails and correlation withSchistosomainfection in a composite sample of school-aged children and adults. The study was carried out between October 2015 and December 2016 in 24 villages located near the Agnéby and Mé coastal river systems in south-eastern Côte d'Ivoire. At each site, snails and prawns were collected, and in each village, 150 individuals were subjected to stool and urine examination f...

International Journal of Biological and Chemical Sciences, 2018

Cross-sectional epidemiological surveys were conducted from December 2012 to January 2013 to bett... more Cross-sectional epidemiological surveys were conducted from December 2012 to January 2013 to better understand the distribution of schistosomiasis and soil-transmitted helminthiasis in the health districts of the Bélier and Marahoué regions in central Côte d'Ivoire. Urine and stool samples were provided by 4900 schoolchildren of 7-14 years old from six health districts. Urine was consecutively analysed by reagent strips and filtration method whilst stool was examined using Kato-Katz method. Eggs of helminth species were identified under a microscope. The investigated schools were georeferenced. The predominant diseases were hookworm infection (12.7%) and urinary schistosomiasis (11.2%). At the health district level, they are a public health problem with moderate prevalence in Tiébissou, Toumodi, Yamoussoukro (Bélier region) and Sinfra (Marahoué region) for urinary schistosomiasis and in Toumodi for hookworm infection. At the school level (i.e. village), the focal and water-related characteristics of schistosomiasis were highlighted mainly alongside Marahoué, Bandama and Kan rivers, and around Lake Kossou where was observed highest prevalence. Hookworm infection and urinary schistosomiasis were sex and age-related. Findings call the need for treatment implementation. In the case of schistosomiasis, however, treatment should be based on the school level instead of the entire health district for an efficient control.

BMC public health, Jan 29, 2018

To achieve a world free of schistosomiasis, the objective is to scale up control and elimination ... more 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 befor...

Infectious Diseases of Poverty, 2017

Background: The construction and operation of small multipurpose dams in Africa have a history of... more Background: The construction and operation of small multipurpose dams in Africa have a history of altering the transmission of water-based diseases, including schistosomiasis. The current study was designed to investigate the abundance and dynamics of schistosomiasis intermediate host snails and Schistosoma infections in humans during the construction and the first years of operation of a small multipurpose dam in Côte d'Ivoire. Methods: The study was carried out in Raffierkro and four neighbouring villages in central Côte d'Ivoire between 2007 and 2012. Snails were collected by two experienced investigators using scoops and forceps for 15 min at each site. Snails were identified at genera and, whenever possible, species level, and subjected to testing for cercarial shedding. Schoolchildren aged 6-15 years were examined once every year for Schistosoma haematobium and S. mansoni infection, using urine filtration and duplication Kato-Katz thick smears, respectively. Additionally, 551 adults were examined for Schistosoma infection before (June 2007) and 359 individuals 2 years after dam construction (June 2009). Results: Overall, 1 700 snails belonging to nine different genera were collected from 19 sampling sites. Bulinus (potential intermediate host snails of S. haematobium) and Pila were the most common genera, whereas Biomphalaria (potential intermediate host snail of S. mansoni), Lymnaea, Physa and Melanoides were found in two villages. During the first-year sampling period, 65 snails were collected, of which 13 (20%) were schistosomiasis intermediate hosts. In subsequent years, out of 1 635 snails collected, 1 079 (66%) were identified as potential intermediate host for schistosomiasis, but none were shedding cercariae. The prevalence of S. mansoni among adults in the study area was low (0.4% in 2007 and 0.3% in 2009), whereas the prevalence of S. haematobium declined from 13.9% to 2.9% in this two-year period.

BMC Zoology

Background Control of intermediate host snails using molluscicides for the control and/or elimina... more Background Control of intermediate host snails using molluscicides for the control and/or elimination of schistosomiasis is a strategy in line with WHO recommendations. Niclosamide is the main chemical molluscicide recommended by WHO. However, except the immediate killing of the snail, the extent of the impact of the molluscicide application on the evolution of snail life-history traits, in relation to recolonization of treated sites is not well known. This study aimed to characterize the spatial variation of life-history traits of populations of the freshwater snail Bulinus truncatus, in relation to niclosamide spraying in the field. From 2016 to 2018, we conducted a trial, using niclosamide to control the intermediate host snails for interrupting the seasonal transmission of urinary schistosomiasis in northern and central Côte d’Ivoire. Five villages (sites) were considered, including three test and two control villages. In the test villages, the molluscicide was sprayed in habita...

Additional file 1: Table S1: Correlations between traits at first reproduction in G1 individuals ... more Additional file 1: Table S1: Correlations between traits at first reproduction in G1 individuals from natural Bulinus truncatus populations according to the region and the treatment status. Table S2: Correlation coefficients for repeated measures between traits at early and late stages for the two study regions and the two treatment statutes. Table S3: Variation of first reproduction parameters of the Bulinus truncatus populations collected before and after niclosamide application in the Linguebo test village.

Background Accurate identification of schistosome species infecting intermediate host snails is i... more Background Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d'Ivoire and confirmed the presence of interspecific hybrid schistosomes. Methods Between June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d'Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification. Results Overall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii w...

Additional file 1: Table S1. Snail collection and schistosome infection data. N = North, C = Cent... more Additional file 1: Table S1. Snail collection and schistosome infection data. N = North, C = Central. Snail identification is based on shell morphology, except for the positive snails that were molecularly identified.

Background: Control of intermediate host snails using molluscicides for the control and/or elimin... more Background: Control of intermediate host snails using molluscicides for the control and/or elimination of schistosomiasis is strategy in the line with WHO recommendations. Niclosamide is the main chemical molluscicide recognized by WHO. However, the extent of the application of molluscicide outside the immediate killing of the snail such as the impact on the evolution of life-history traits; in relation to recolonization of treated sites is less or not known. This study aimed to characterize the spatial variation of life-history traits in Bulinus truncatus populations in north and central Côte d’Ivoire, in relation to niclosamide spraying in the field.From 2016 to 2018, we conducted a trial to control the intermediate host snails for interrupting seasonal transmission urinary schistosomiasis in northern and central Côte d’Ivoire, using niclosamide. The molluscicide was sprayed three times per year in habitats harboring the freshwater snail B. truncatus. Snails were collected before ...

International Journal of Innovation and Applied Studies, 2015

Presumptive diagnosis of malaria remains a common practice in several health facilities in C

PLOS Neglected Tropical Diseases, 2021

Background Preventive chemotherapy using praziquantel is the mainstay for schistosomiasis control... more Background Preventive chemotherapy using praziquantel is the mainstay for schistosomiasis control. However, there is little evidence on what is supposed to be the most effective school-based treatment strategy to sustain morbidity control. The aim of this study was to compare differences in Schistosoma mansoni prevalence and infection intensity between three different schedules of school-based preventive chemotherapy in an area with moderate prevalence of S. mansoni in Côte d’Ivoire. Methodology Seventy-five schools were randomly assigned to one of three intervention arms: (i) annual school-based preventive chemotherapy with praziquantel (40 mg/kg) over four years; (ii) praziquantel treatment only in the first two years, followed by two years whithout treatment; and (iii) praziquantel treatment in years 1 and 3 without treatment in-between. Cross-sectional parasitologic surveys were carried out prior to each round of preventive chemotherapy. The difference in S. mansoni prevalence a...

Tropical Medicine and Infectious Disease, 2021

In order to assess the impact of different control strategies against Schistosoma haematobium in ... more In order to assess the impact of different control strategies against Schistosoma haematobium in seasonal transmission foci in Côte d’Ivoire, a three-year cluster randomized trial was implemented. The decrease in S. haematobium prevalence among children aged 9−12 years was the primary outcome. In the first step, an eligibility survey was conducted, subjecting 50 children aged 13−14 years to a single urine filtration. Sixty-four villages with a prevalence of S. haematobium of ≥4% were selected and randomly assigned to four intervention arms consisting of annual mass drug administration (MDA) before (arm 1) and after (arm 2) the peak transmission, biannual treatment with praziquantel before and after the peak transmission season (arm 3), and annual MDA before the peak transmission season, coupled with focal chemical snail control using molluscicides (arm 4). At baseline, we observed a prevalence of 24.8%, 10.1%, 13.9%, and 15.9% in study arms 1, 2, 3, and 4, respectively. One year aft...

Frontiers in Tropical Diseases, 2021

IntroductionTraditionallySchistosoma mansoniinfection is diagnosed by the Kato-Katz method. Thick... more IntroductionTraditionallySchistosoma mansoniinfection 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.MethodsPOC-CCA was used to pre-screen forS. mansoniinfection. Children with positive results were tested by the Kato-Katz method, and those with positive Kato-Katz results (>1 egg/1 occurrence) were enrolled. Participants (N=444) were treat...

Clinical Infectious Diseases, 2021

Background Annual mass drug administration (MDA) using praziquantel is the cornerstone of schisto... more Background Annual mass drug administration (MDA) using praziquantel is the cornerstone of schistosomiasis morbidity control but is not sufficient to interrupt transmission. We implemented a cluster-randomized trial to compare the effectiveness of 4 different intervention packages to interrupt transmission of Schistosoma haematobium in a seasonal transmission setting of Côte d’Ivoire. Methods Sixty-four localities with a S. haematobium prevalence in school children aged 13–14 years above 4% were randomly assigned to 1 of 4 intervention arms over a 3-year period: (1) the current standard strategy consisting of annual MDA before peak of transmission, (2) annual MDA after peak of transmission, (3) biannual MDA, and (4) standard MDA combined with snail control. The primary outcome was prevalence and intensity of S. haematobium infection in children aged 9–12 years 1 year after the final intervention, using urine filtration performed by experienced microscopists. Results By study end, we ...

Journal of Applied Biosciences, 2021

Objectif : Identifier les espèces Schistosoma haematobium, S. bovis et leurs hybrides et, évaluer... more Objectif : Identifier les espèces Schistosoma haematobium, S. bovis et leurs hybrides et, évaluer la compatibilité des schistosomes avec les mollusques hôtes intermédiaires et la souris blanche (Mus musculus albinos), hôte définitif, en infestation expérimentale. Méthodologie et résultats : Des schistosomes ont été obtenus à partir de bulins infestés naturellement ou expérimentalement avec des miracidiums provenant des urines de l’homme. Ils ont permis d’étudier la compatibilité de quatre populations de Bulinus truncatus avec deux souches du groupe S. haematobium. La chronobiologie cercarienne a été étudiée à partir de quatre tranches horaires : 6-10h, 10-12h, 12-15h et 15- 18h. Des souris blanches infestées expérimentalement, ont été perfusées pour dénombrer les vers adultes. Une meilleure compatibilité schistosome-mollusque a été observée au niveau des infestations sympatriques. Le pic d’émergence cercarienne pour les mollusques naturellement infestés a été observé entre 6-10h, 10...

The American Journal of Tropical Medicine and Hygiene, 2020

As part of its diverse portfolio, the Schistosomiasis Consortium for Operational Research and Eva... more As part of its diverse portfolio, the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) included two cluster-randomized trials evaluating interventions that could potentially lead to interruption of schistosomiasis transmission (elimination) in areas of Africa with low prevalence and intensity of infection. These studies, conducted in Zanzibar and Côte d'Ivoire, demonstrated that multiyear mass drug administration (MDA) with praziquantel failed to interrupt the transmission of urogenital schistosomiasis, even when provided biannually and/or supplemented by small-scale implementation of additional interventions. Other SCORE activities related to elimination included a feasibility and acceptability assessment of test-treat-track-test-treat (T5) strategies and mathematical modeling. Future evaluations of interventions to eliminate schistosomiasis should recognize the difficulties inherent in conducting randomized controlled trials on elimination and in measuring small changes where baseline prevalence is low. Highly sensitive and specific diagnostic tests for use in very low-prevalence areas for schistosomiasis are not routinely available, which complicates accurate measurement of infection rates and assessment of changes resulting from interventions in these settings. Although not encountered in these two studies, as prevalence and intensity decrease, political and community commitment to population-wide MDA may decrease. Because of this potential problem, SCORE developed and funded the T5 strategy implemented in Egypt, Kenya, and Tanzania. It is likely that focal MDA campaigns, along with more targeted approaches, including a T5 strategy and snail control, will need to be supplemented with the provision of clean water and sanitation and behavior change communications to achieve interruption of schistosome transmission.

The American Journal of Tropical Medicine and Hygiene, 2020

The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) was created in 200... more 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.

BMC Public Health, 2018

Background: Parasitic worms (helminths) are common infections in low-and middle-income countries.... more 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.

Bulletin of Entomological Research, 2017

Since 2008, several outbreaks of yellow fever and dengue occurred in Abidjan, the economic capita... more Since 2008, several outbreaks of yellow fever and dengue occurred in Abidjan, the economic capital of Côte d'Ivoire. A better knowledge of the biology of Aedes aegypti populations, the main vector of yellow fever and dengue viruses, is necessary to tailor vector control strategies implemented in the city. This study was designed to determine some biological parameters, occurring during the life cycle of two morphological phenotypes of Ae. aegypti larvae. Mosquitoes were sampled in a suburb of Abidjan (Treichville) using the WHO layer-traps technique. Biological parameters were studied in laboratory under standard conditions of temperature (27°C ± 2°C) and relative humidity (80% ± 10%). Our results indicated that the mean eggs laid by females from ‘brown larvae’ (BL) (85.95, 95% confidence interval (CI 95%) 78.87–93.02) was higher than those from ‘white larvae’ (WL) (64.40%, CI 95% 55.27–73.54). The gonotrophic cycle was 3 and 4 days in females from BL and WL, respectively. The o...

Parasitology, 2018

The current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziq... more The current emphasis of schistosomiasis control is placed on preventive chemotherapy using praziquantel. However, reinfection may occur rapidly in the absence of complementary interventions. Recent studies from Senegal suggest that predatory prawns might feed on intermediate host snails and thus impact on schistosomiasis transmission. We designed a study with four repeated cross-sectional surveys pertaining to prawns and snails, coupled with a single cross-sectional parasitological survey among humans. We assessed for potential associations between the presence/density of prawns and snails and correlation withSchistosomainfection in a composite sample of school-aged children and adults. The study was carried out between October 2015 and December 2016 in 24 villages located near the Agnéby and Mé coastal river systems in south-eastern Côte d'Ivoire. At each site, snails and prawns were collected, and in each village, 150 individuals were subjected to stool and urine examination f...

International Journal of Biological and Chemical Sciences, 2018

Cross-sectional epidemiological surveys were conducted from December 2012 to January 2013 to bett... more Cross-sectional epidemiological surveys were conducted from December 2012 to January 2013 to better understand the distribution of schistosomiasis and soil-transmitted helminthiasis in the health districts of the Bélier and Marahoué regions in central Côte d'Ivoire. Urine and stool samples were provided by 4900 schoolchildren of 7-14 years old from six health districts. Urine was consecutively analysed by reagent strips and filtration method whilst stool was examined using Kato-Katz method. Eggs of helminth species were identified under a microscope. The investigated schools were georeferenced. The predominant diseases were hookworm infection (12.7%) and urinary schistosomiasis (11.2%). At the health district level, they are a public health problem with moderate prevalence in Tiébissou, Toumodi, Yamoussoukro (Bélier region) and Sinfra (Marahoué region) for urinary schistosomiasis and in Toumodi for hookworm infection. At the school level (i.e. village), the focal and water-related characteristics of schistosomiasis were highlighted mainly alongside Marahoué, Bandama and Kan rivers, and around Lake Kossou where was observed highest prevalence. Hookworm infection and urinary schistosomiasis were sex and age-related. Findings call the need for treatment implementation. In the case of schistosomiasis, however, treatment should be based on the school level instead of the entire health district for an efficient control.

BMC public health, Jan 29, 2018

To achieve a world free of schistosomiasis, the objective is to scale up control and elimination ... more 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 befor...

Infectious Diseases of Poverty, 2017

Background: The construction and operation of small multipurpose dams in Africa have a history of... more Background: The construction and operation of small multipurpose dams in Africa have a history of altering the transmission of water-based diseases, including schistosomiasis. The current study was designed to investigate the abundance and dynamics of schistosomiasis intermediate host snails and Schistosoma infections in humans during the construction and the first years of operation of a small multipurpose dam in Côte d'Ivoire. Methods: The study was carried out in Raffierkro and four neighbouring villages in central Côte d'Ivoire between 2007 and 2012. Snails were collected by two experienced investigators using scoops and forceps for 15 min at each site. Snails were identified at genera and, whenever possible, species level, and subjected to testing for cercarial shedding. Schoolchildren aged 6-15 years were examined once every year for Schistosoma haematobium and S. mansoni infection, using urine filtration and duplication Kato-Katz thick smears, respectively. Additionally, 551 adults were examined for Schistosoma infection before (June 2007) and 359 individuals 2 years after dam construction (June 2009). Results: Overall, 1 700 snails belonging to nine different genera were collected from 19 sampling sites. Bulinus (potential intermediate host snails of S. haematobium) and Pila were the most common genera, whereas Biomphalaria (potential intermediate host snail of S. mansoni), Lymnaea, Physa and Melanoides were found in two villages. During the first-year sampling period, 65 snails were collected, of which 13 (20%) were schistosomiasis intermediate hosts. In subsequent years, out of 1 635 snails collected, 1 079 (66%) were identified as potential intermediate host for schistosomiasis, but none were shedding cercariae. The prevalence of S. mansoni among adults in the study area was low (0.4% in 2007 and 0.3% in 2009), whereas the prevalence of S. haematobium declined from 13.9% to 2.9% in this two-year period.