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Osborne A, Bangura C. Predictors of insecticide-treated bed nets use among pregnant women in Sierra Leone: evidence from the 2019 Sierra Leone Demographic Health Survey. Malar J 2024; 23:193. [PMID: 38898414 PMCID: PMC11188154 DOI: 10.1186/s12936-024-05018-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024] Open
Abstract
BACKGROUND Malaria remains a significant public health threat in Sierra Leone, particularly for pregnant women and their unborn children. Infection during pregnancy can lead to severe consequences, including maternal anaemia, low birth weight, premature birth, and even death. Therefore, preventing malaria during pregnancy is crucial for improving maternal and child health outcomes. This study investigated the predictors of insecticide-treated bed net (ITN) use among pregnant women in Sierra Leone. METHODS The study analysed the 2019 Sierra Leone Demographic and Health Survey data (SLDHS). The study comprised a total of 900 pregnant women aged 15-49 years, representing the nationally representative sample. A multivariable binary regression analysis was used to explore the predictors of ITN use. The regression results were presented using an adjusted odds ratio (AOR) with 95% confidence intervals (CI). RESULTS The study found that the prevalence of ITN use among pregnant women was 64.2 [60.4, 67.9] in Sierra Leone. Pregnant women who were married [aOR = 2.02, 95% CI 1.32, 3.07] had higher odds of bed net use than those who were unmarried. Pregnant women with five or more children [aOR = 1.69, 95% CI 1.01, 2.84] had higher odds of mosquito bed net use than those with four and below children. Pregnant women living in the Northern, Northwestern, Southern and Western regions all had lower odds of bed net use than those in the Eastern region, with the lowest odds among those living in the western region [aOR = 0.19, 95% CI 0.09, 0.40]. Pregnant women who were Muslims [aOR = 0.63, 95% CI 0.41, 0.95] had lower odds of mosquito bed net use than Christians. Pregnant women with female household heads [aOR = 0.65, 95% CI 0.44, 0.95] had lower odds of mosquito bed net use than those with male household heads. CONCLUSION ITN use among pregnant women in Sierra Leone remains suboptimal. Marital status, parity, sex of household head, region and religion were associated with bed net use. The government and policymakers in Sierra Leone should integrate ITN education and distribution into prenatal care services, emphasizing the benefits for both mother and baby-partnering with healthcare providers to raise awareness and encourage consistent use. Involve local leaders, religious figures, and mothers' groups to promote the benefits of ITN during pregnancy. Educate husbands and partners on the importance of ITN use during pregnancy and encourage their support in its consistent use.
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Affiliation(s)
- Augustus Osborne
- Department of Biological Sciences, School of Basic Sciences, Njala University, PMB, Freetown, Sierra Leone.
| | - Camilla Bangura
- Department of Biological Sciences, School of Basic Sciences, Njala University, PMB, Freetown, Sierra Leone
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Kargbo-Labour I, Redwood-Sawyerr V, Conteh A, Chop E, Bah MS, Koroma A, Kabia U, Klein L, Juneja S, Houck P, Reid S, Evans D, Weaver AM, Phillips AE, Zhang Y. Re-assessment of schistosomiasis in nine endemic districts with cluster sampling in Sierra Leone. Front Public Health 2024; 12:1415486. [PMID: 38932788 PMCID: PMC11199885 DOI: 10.3389/fpubh.2024.1415486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 05/23/2024] [Indexed: 06/28/2024] Open
Abstract
Background Baseline mapping showed that schistosomiasis was highly/moderately endemic in nine districts in Sierra Leone. Mass drug administration (MDA) with praziquantel started in 2009, and after multiple rounds of treatment, an impact assessment was conducted in 2016 followed by a second re-assessment in 2022 using cluster sampling to provide more granular data for refining chiefdom (sub-district) treatment strategies. Methods On average, 20 rural villages were systematically selected per district by probability proportional to population size across the nine districts. Surveys were conducted in schools, and 24 school children aged between 5 and 14 years were randomly selected, with an equal number of boys and girls. One stool sample and one urine sample were collected per child. Two Kato-Katz slides were examined per stool for Schistosoma mansoni infection. Hemastix strips were used as a proxy for S. haematobium infection with urine filtration used for egg counts on hematuria-positive samples. Results In total, 4,736 stool samples and 4,618 urine samples were examined across 200 schools in 125 chiefdoms. Overall, the prevalence of S. mansoni was 16.3% (95% CI: 15.3-17.4%), while the overall prevalence of S. haematobium was 2.0% (95% CI: 1.6-2.4%) by hematuria. The prevalence of heavy infections for S. mansoni and S. haematobium was 1.5% (95% CI: 1.1-1.9%) and 0.02% (95% CI: 0.0-0.14%), respectively. Among 125 chiefdoms surveyed, the overall schistosomiasis prevalence was <10% in 65 chiefdoms, 10-49.9% in 47 chiefdoms, and ≥ 50% in 13 chiefdoms. There was a mixed relationship between schistosomiasis in school children and WASH access in schools. Conclusion Sierra Leone has made significant progress in reducing schistosomiasis prevalence across the country after a decade of MDA intervention. However, high prevalence remains in some hotspot chiefdoms. The next steps are for the national program to investigate and address any potential issues such as low coverage or poor knowledge of schistosomiasis risk behaviors and, where appropriate, consider broadening to community-wide treatment in hotspot chiefdoms or communities.
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Affiliation(s)
- Ibrahim Kargbo-Labour
- National Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | - Abdulai Conteh
- National Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | | | | | | | | | | | | | - Steven Reid
- Helen Keller International, New York, NY, United States
| | - Darin Evans
- United States Agency for International Development, Washington, DC, United States
| | | | | | - Yaobi Zhang
- Helen Keller International, New York, NY, United States
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Macharia PM, Ray N, Gitonga CW, Snow RW, Giorgi E. Combining school-catchment area models with geostatistical models for analysing school survey data from low-resource settings: Inferential benefits and limitations. SPATIAL STATISTICS 2022; 51:100679. [PMID: 35880005 PMCID: PMC7613137 DOI: 10.1016/j.spasta.2022.100679] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
School-based sampling has been used to inform targeted responses for malaria and neglected tropical diseases. Standard geostatistical methods for mapping disease prevalence use the school location to model spatial correlation, which is questionable since exposure to the disease is more likely to occur in the residential location. In this paper, we propose to overcome the limitations of standard geostatistical methods by introducing a modelling framework that accounts for the uncertainty in the location of the residence of the students. By using cost distance and cost allocation models to define spatial accessibility and in absence of any information on the travel mode of students to school, we consider three school catchment area models that assume walking only, walking and bicycling and, walking and motorized transport. We illustrate the use of this approach using two case studies of malaria in Kenya and compare it with the standard approach that uses the school locations to build geostatistical models. We argue that the proposed modelling framework presents several inferential benefits, such as the ability to combine data from multiple surveys some of which may also record the residence location, and to deal with ecological bias when estimating the effects of malaria risk factors. However, our results show that invalid assumptions on the modes of travel to school can worsen the predictive performance of geostatistical models. Future research in this area should focus on collecting information on the modes of transportation to school which can then be used to better parametrize the catchment area models.
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Affiliation(s)
- Peter M. Macharia
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, LA1 4YW, UK
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, PO, Box 43640, Nairobi, Kenya
| | - Nicolas Ray
- GeoHealth group, Institute of Global Health, University of Geneva, Geneva, Switzerland
- Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland
| | - Caroline W. Gitonga
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, PO, Box 43640, Nairobi, Kenya
| | - Robert W. Snow
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, PO, Box 43640, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7LG, UK
| | - Emanuele Giorgi
- Centre for Health Informatics, Computing, and Statistics, Lancaster Medical School, Lancaster University, Lancaster, LA1 4YW, UK
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Duan L, Wang L, Lu S, Wang B, Li Y, Xu Q, Huang L, Ding W, Qian Y, Li H, Ma X, Wang D, Guan Y, Wang X, Xiao N, Zhou XN. Development and Impacts of the Sierra Leone-China Laboratory for Parasitic Diseases Testing and Surveillance. China CDC Wkly 2021; 3:327-330. [PMID: 34594877 PMCID: PMC8393174 DOI: 10.46234/ccdcw2021.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/02/2021] [Indexed: 11/30/2022] Open
Affiliation(s)
- Lei Duan
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Lili Wang
- Center for Global Public Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Shenning Lu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Bei Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Yanbing Li
- Department of Laboratory Medicine, Central South University, Changsha, Hunan, China
| | - Qiuli Xu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Lulu Huang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Wei Ding
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Yingjun Qian
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Hongmei Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Xuejiao Ma
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Duoquan Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Yayi Guan
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Xiaochun Wang
- Center for Global Public Health, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Ning Xiao
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention; Chinese Center for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Center for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, National Health Commission of China, Shanghai, China
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Fornace KM, Fronterrè C, Fleming FM, Simpson H, Zoure H, Rebollo M, Mwinzi P, Vounatsou P, Pullan RL. Evaluating survey designs for targeting preventive chemotherapy against Schistosoma haematobium and Schistosoma mansoni across sub-Saharan Africa: a geostatistical analysis and modelling study. Parasit Vectors 2020; 13:555. [PMID: 33203463 PMCID: PMC7672864 DOI: 10.1186/s13071-020-04413-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/21/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Schistosomiasis control programmes primarily use school-based surveys to identify areas for mass drug administration of preventive chemotherapy. However, as the spatial distribution of schistosomiasis can be highly focal, transmission may not be detected by surveys implemented at districts or larger spatial units. Improved mapping strategies are required to accurately and cost-effectively target preventive chemotherapy to remaining foci across all possible spatial distributions of schistosomiasis. METHODS Here, we use geostatistical models to quantify the spatial heterogeneity of Schistosoma haematobium and S. mansoni across sub-Saharan Africa using the most comprehensive dataset available on school-based surveys. Applying this information to parameterise simulations, we assess the accuracy and cost of targeting alternative implementation unit sizes across the range of plausible schistosomiasis distributions. We evaluate the consequences of decisions based on survey designs implemented at district and subdistrict levels sampling different numbers of schools. Cost data were obtained from field surveys conducted across multiple countries and years, with cost effectiveness evaluated as the cost per correctly identified school. RESULTS Models identified marked differences in prevalence and spatial distributions between countries and species; however, results suggest implementing surveys at subdistrict level increase the accuracy of treatment classifications across most scenarios. While sampling intensively at the subdistrict level resulted in the highest classification accuracy, this sampling strategy resulted in the highest costs. Alternatively, sampling the same numbers of schools currently recommended at the district level but stratifying by subdistrict increased cost effectiveness. CONCLUSIONS This study provides a new tool to evaluate schistosomiasis survey designs across a range of transmission settings. Results highlight the importance of considering spatial structure when designing sampling strategies, illustrating that a substantial proportion of children may be undertreated even when an implementation unit is correctly classified. Control programmes need to weigh the increased accuracy of more detailed mapping strategies against the survey costs and treatment priorities.
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Affiliation(s)
- Kimberly M Fornace
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
| | - Claudio Fronterrè
- Centre for Health Informatics, Computing and Statistics (CHICAS), Lancaster University, Lancaster, UK
| | | | - Hope Simpson
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Honorat Zoure
- Expanded Special Project of the Elimination of Neglected Tropical Diseases (ESPEN), Africa Regional Office of the World Health Organisation, Brazzaville, Congo
| | - Maria Rebollo
- Expanded Special Project of the Elimination of Neglected Tropical Diseases (ESPEN), Africa Regional Office of the World Health Organisation, Brazzaville, Congo
| | - Pauline Mwinzi
- Expanded Special Project of the Elimination of Neglected Tropical Diseases (ESPEN), Africa Regional Office of the World Health Organisation, Brazzaville, Congo
| | | | - Rachel L Pullan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Bah YM, Bah MS, Paye J, Conteh A, Saffa S, Tia A, Sonnie M, Veinoglou A, Amon JJ, Hodges MH, Zhang Y. Soil-transmitted helminth infection in school age children in Sierra Leone after a decade of preventive chemotherapy interventions. Infect Dis Poverty 2019; 8:41. [PMID: 31262367 PMCID: PMC6604471 DOI: 10.1186/s40249-019-0553-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 05/22/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Baseline mapping of soil-transmitted helminth (STH) infections among school age children (SAC) in 2008-2009 found high or moderate prevalence in 13 of the 14 districts in Sierra Leone. Following these surveys, mass drug administration (MDA) of mebendazole/albendazole was conducted biannually at national level targeting pre-school children (PSC) aged 12-59 months and intermittently at sub-national level targeting SAC. In addition, MDA with ivermectin and albendazole for eliminating lymphatic filariasis (LF) has been conducted nationwide since 2010 targeting individuals over 5 years of age. Each MDA achieved high coverage, except in 2014 when all but one round of MDA for PSC was cancelled due to the Ebola emergency. The objective of the current study was to determine the prevalence and intensity of STH infections among SAC after a decade of these deworming campaigns. METHODS Seventy-three schools in 14 districts were purposefully selected, including 39 schools from the baseline surveys, with approximately two sites from each of low, moderate and high prevalence categories at baseline per district. Fresh stool samples were collected from 3632 children aged 9-14 years (male 51%, female 49%) and examined using the Kato Katz technique. RESULTS The prevalence of STH infections in Sierra Leone decreased in 2016 compared to 2008: Ascaris lumbricoides 4.4% (95% confidence interval [CI]: 3.7-5.1%) versus 6.6% (95% CI: 0-25%), Trichuris trichiura 0.7% (95% CI: 0.5-1.1%) versus 1.8% (95% CI: 0-30.2%), hookworm 14.9% (95% CI: 13.8-16.1) versus 38.5% (95% CI: 5.4-95.1%), and any STH 18.3% (95% CI:17.0-19.5%) versus 48.3% (CI: 5.4-96.3%), respectively. In 2016, no district had high hookworm prevalence and four districts had moderate prevalence, compared with eight and four districts respectively in 2008. In 2016, the arithmetic mean hookworm egg count in all children examined was light: 45.5 eggs per gram (EPG) of faeces, (95% CI:\ 35.96-55.07 EPG); three (0.08%) children had heavy infections and nine (0.25%) children had moderate infections. CONCLUSIONS Sierra Leone has made considerable progress toward controlling STH as a public health problem among SAC. As LF MDA phases out (between 2017 and 2021), transition of deworming to other platforms and water and sanitation strategies need to be strengthened to maintain STH control and ultimately interrupt transmission.
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Affiliation(s)
- Yakuba Mohamed Bah
- Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | - Jusufu Paye
- Helen Keller International, Freetown, Sierra Leone
| | - Abdulai Conteh
- Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Sam Saffa
- Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Alie Tia
- Neglected Tropical Disease Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | | | | | | | - Yaobi Zhang
- Helen Keller International, Regional Office for Africa, Yoff-Dakar, Senegal
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Bah YM, Paye J, Bah MS, Conteh A, Saffa S, Tia A, Sonnie M, Veinoglou A, Hodges MH, Zhang Y. Schistosomiasis in School Age Children in Sierra Leone After 6 Years of Mass Drug Administration With Praziquantel. Front Public Health 2019; 7:1. [PMID: 30809516 PMCID: PMC6379326 DOI: 10.3389/fpubh.2019.00001] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 01/03/2019] [Indexed: 01/04/2023] Open
Abstract
Historic data and baseline surveys showed schistosomiasis as highly/moderately endemic in 7 of 14 districts in Sierra Leone, justifying annual/biennial mass drug administration (MDA) with praziquantel. MDA commenced in 2009 and reported treatment coverage had been above the World Health Organization recommended 75% of target population. Assessment in 2012 showed significant reduction in infection. In 2016, another national school-based survey was conducted to evaluate the progress. Two schools from each category (high, moderate or low) of endemic communities in each MDA district and five schools in non-MDA districts were selected. Fifty children (25 boys and 25 girls) aged 9-14 years were randomly selected per school. Parasitological examination of 1,980 stool and 1,382 urine samples were conducted. Overall Schistosoma mansoni prevalence in the seven MDA districts decreased to 20.4% (95% CI: 18.7-22.3%) in 2016 from 42.2% (95% CI: 39.8-44.5%) at baseline (p < 0.0001). Mean overall S. mansoni intensity of infection reduced to 52.8 epg (95% CI: 43.2-62.4 epg) in 2016 from 100.5 epg (95% CI: 88.7-112.3 epg) at baseline (p < 0.001). The prevalence of Schistosoma haematobium in the five MDA districts that had baseline prevalence data decreased to 2.2% (95% CI: 1.5-3.1%) in 2016 from 18.3% (95% CI: 16.3-20.5%) at baseline (p < 0.0001). Mean overall intensity of infection increased to 1.12 e/10 ml (95% CI: 0.55-0.1.70 e/10 ml) in 2016 compared to 0.47 e/10 ml (95% CI: 0.16-0.78 e/10 ml) in 2012 (p < 0.05) (no baseline data). No district was highly endemic in 2016 compared to three at baseline and there was no significant difference in prevalence or intensity of infection by sex for both species. This survey illustrated the significant progress made in controlling schistosomiasis in Sierra Leone. The fact that prevalence and intensity of infection showed an increase from the 2010 level suggested a detrimental effect of missing MDA due to the Ebola toward schistosomiasis control. The national program needs to continue the treatment and adopt a comprehensive approach including water, hygiene, and sanitation measures to achieve control and elimination of schistosomiasis.
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Affiliation(s)
- Yakuba M. Bah
- Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Jusufu Paye
- Helen Keller International, Freetown, Sierra Leone
| | | | - Abdulai Conteh
- Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Sam Saffa
- Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Alie Tia
- Neglected Tropical Disease Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | | | - Amy Veinoglou
- Headquarters, Helen Keller International, New York, NY, United States
| | | | - Yaobi Zhang
- Regional Office for Africa, Helen Keller International, Dakar, Senegal
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Sokolow SH, Wood CL, Jones IJ, Lafferty KD, Kuris AM, Hsieh MH, De Leo GA. To Reduce the Global Burden of Human Schistosomiasis, Use 'Old Fashioned' Snail Control. Trends Parasitol 2018; 34:23-40. [PMID: 29126819 PMCID: PMC5819334 DOI: 10.1016/j.pt.2017.10.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/30/2017] [Accepted: 10/16/2017] [Indexed: 12/27/2022]
Abstract
Control strategies to reduce human schistosomiasis have evolved from 'snail picking' campaigns, a century ago, to modern wide-scale human treatment campaigns, or preventive chemotherapy. Unfortunately, despite the rise in preventive chemotherapy campaigns, just as many people suffer from schistosomiasis today as they did 50 years ago. Snail control can complement preventive chemotherapy by reducing the risk of transmission from snails to humans. Here, we present ideas for modernizing and scaling up snail control, including spatiotemporal targeting, environmental diagnostics, better molluscicides, new technologies (e.g., gene drive), and 'outside the box' strategies such as natural enemies, traps, and repellants. We conclude that, to achieve the World Health Assembly's stated goal to eliminate schistosomiasis, it is time to give snail control another look.
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Affiliation(s)
- Susanne H Sokolow
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
| | - Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195-5020, USA
| | - Isabel J Jones
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Kevin D Lafferty
- U.S. Geological Survey, Western Ecological Research Center, c/o Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Armand M Kuris
- Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Michael H Hsieh
- Children's National Health System, Washington DC, 20010, USA; The George Washington University, Washington DC, 20037, USA; Biomedical Research Institute, Rockville, MD 20850, USA
| | - Giulio A De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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Knowles SCL, Sturrock HJW, Turner H, Whitton JM, Gower CM, Jemu S, Phillips AE, Meite A, Thomas B, Kollie K, Thomas C, Rebollo MP, Styles B, Clements M, Fenwick A, Harrison WE, Fleming FM. Optimising cluster survey design for planning schistosomiasis preventive chemotherapy. PLoS Negl Trop Dis 2017; 11:e0005599. [PMID: 28552961 PMCID: PMC5464666 DOI: 10.1371/journal.pntd.0005599] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 06/08/2017] [Accepted: 04/26/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The cornerstone of current schistosomiasis control programmes is delivery of praziquantel to at-risk populations. Such preventive chemotherapy requires accurate information on the geographic distribution of infection, yet the performance of alternative survey designs for estimating prevalence and converting this into treatment decisions has not been thoroughly evaluated. METHODOLOGY/PRINCIPAL FINDINGS We used baseline schistosomiasis mapping surveys from three countries (Malawi, Côte d'Ivoire and Liberia) to generate spatially realistic gold standard datasets, against which we tested alternative two-stage cluster survey designs. We assessed how sampling different numbers of schools per district (2-20) and children per school (10-50) influences the accuracy of prevalence estimates and treatment class assignment, and we compared survey cost-efficiency using data from Malawi. Due to the focal nature of schistosomiasis, up to 53% simulated surveys involving 2-5 schools per district failed to detect schistosomiasis in low endemicity areas (1-10% prevalence). Increasing the number of schools surveyed per district improved treatment class assignment far more than increasing the number of children sampled per school. For Malawi, surveys of 15 schools per district and 20-30 children per school reliably detected endemic schistosomiasis and maximised cost-efficiency. In sensitivity analyses where treatment costs and the country considered were varied, optimal survey size was remarkably consistent, with cost-efficiency maximised at 15-20 schools per district. CONCLUSIONS/SIGNIFICANCE Among two-stage cluster surveys for schistosomiasis, our simulations indicated that surveying 15-20 schools per district and 20-30 children per school optimised cost-efficiency and minimised the risk of under-treatment, with surveys involving more schools of greater cost-efficiency as treatment costs rose.
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Affiliation(s)
- Sarah C. L. Knowles
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- * E-mail:
| | - Hugh J. W. Sturrock
- Global Health Group, University of California San Francisco, San Francisco, California, United States of America
| | - Hugo Turner
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
| | - Jane M. Whitton
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
| | - Charlotte M. Gower
- The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
| | - Samuel Jemu
- Ministry of Health, Capital City, Lilongwe 3, Malawi
| | - Anna E. Phillips
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
| | - Aboulaye Meite
- Ministry of Health and Social Welfare of Côte d’Ivoire, Abidjan, Côte d’Ivoire
| | - Brent Thomas
- Fliarial Programme Support Unit, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Karsor Kollie
- Neglected Tropical and Non Communicable Diseases Program, Ministry of Health and Social Welfare, Monrovia 10, Liberia
| | - Catherine Thomas
- Neglected Tropical and Non Communicable Diseases Program, Ministry of Health and Social Welfare, Monrovia 10, Liberia
| | - Maria P. Rebollo
- Fliarial Programme Support Unit, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, United Kingdom
| | - Ben Styles
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- National Foundation for Educational Research, Upton Park, Slough, United Kingdom
| | - Michelle Clements
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
| | - Alan Fenwick
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
| | - Wendy E. Harrison
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
| | - Fiona M. Fleming
- Schistosomiasis Control Initiative, Department of Infectious Disease Epidemiology, Imperial College London, St. Mary’s Campus, Norfolk Place, London, United Kingdom
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
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Overgaard HJ, Alexander N, Matiz MI, Jaramillo JF, Olano VA, Vargas S, Sarmiento D, Lenhart A, Stenström TA. A Cluster-Randomized Controlled Trial to Reduce Diarrheal Disease and Dengue Entomological Risk Factors in Rural Primary Schools in Colombia. PLoS Negl Trop Dis 2016; 10:e0005106. [PMID: 27820821 PMCID: PMC5098800 DOI: 10.1371/journal.pntd.0005106] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 10/12/2016] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND As many neglected tropical diseases are co-endemic and have common risk factors, integrated control can efficiently reduce disease burden and relieve resource-strained public health budgets. Diarrheal diseases and dengue fever are major global health problems sharing common risk factors in water storage containers. Where provision of clean water is inadequate, water storage is crucial. Fecal contamination of stored water is a common source of diarrheal illness, but stored water also provides breeding sites for dengue vector mosquitoes. Integrating improved water management and educational strategies for both diseases in the school environment can potentially improve the health situation for students and the larger community. The objective of this trial was to investigate whether interventions targeting diarrhea and dengue risk factors would significantly reduce absence due to diarrheal disease and dengue entomological risk factors in schools. METHODOLOGY/PRINCIPAL FINDINGS A factorial cluster randomized controlled trial was carried out in 34 rural primary schools (1,301 pupils) in La Mesa and Anapoima municipalities, Cundinamarca, Colombia. Schools were randomized to one of four study arms: diarrhea interventions (DIA), dengue interventions (DEN), combined diarrhea and dengue interventions (DIADEN), and control (CON). Interventions had no apparent effect on pupil school absence due to diarrheal disease (p = 0.45) or on adult female Aedes aegypti density (p = 0.32) (primary outcomes). However, the dengue interventions reduced the Breteau Index on average by 78% (p = 0.029), with Breteau indices of 10.8 and 6.2 in the DEN and DIADEN arms, respectively compared to 37.5 and 46.9 in the DIA and CON arms, respectively. The diarrhea interventions improved water quality as assessed by the amount of Escherichia coli colony forming units (CFU); the ratio of Williams mean E. coli CFU being 0.22, or 78% reduction (p = 0.008). CONCLUSIONS/SIGNIFICANCE Integrated control of dengue and diarrhea has never been conducted before. This trial presents an example for application of control strategies that may affect both diseases and the first study to apply such an approach in school settings. The interventions were well received and highly appreciated by students and teachers. An apparent absence of effect in primary outcome indicators could be the result of pupils being exposed to risk factors outside the school area and mosquitoes flying in from nearby uncontrolled breeding sites. Integrated interventions targeting these diseases in a school context remain promising because of the reduced mosquito breeding and improved water quality, as well as educational benefits. However, to improve outcomes in future integrated approaches, simultaneous interventions in communities, in addition to schools, should be considered; using appropriate combinations of site-specific, effective, acceptable, and affordable interventions. TRIAL REGISTRATION ClinicalTrials.gov no. ISRCTN40195031.
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Affiliation(s)
- Hans J. Overgaard
- Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, Norway
- Institut de Recherche pour le Développement, Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle, Montpellier, France
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Neal Alexander
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London
| | - Maria Ines Matiz
- Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia
| | | | | | - Sandra Vargas
- Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia
| | - Diana Sarmiento
- Instituto de Salud y Ambiente, Universidad El Bosque, Bogota, Colombia
| | - Audrey Lenhart
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- U.S. Centers for Disease Control and Prevention, Atlanta, United States of America
| | - Thor Axel Stenström
- SARChI Chair, Institute for Water and Waste Water Technology, Durban University of Technology, Durban, South Africa
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Xu J, Yu Q, Tchuenté LAT, Bergquist R, Sacko M, Utzinger J, Lin DD, Yang K, Zhang LJ, Wang Q, Li SZ, Guo JG, Zhou XN. Enhancing collaboration between China and African countries for schistosomiasis control. THE LANCET. INFECTIOUS DISEASES 2016; 16:376-83. [PMID: 26851829 DOI: 10.1016/s1473-3099(15)00360-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 09/19/2015] [Accepted: 09/30/2015] [Indexed: 11/25/2022]
Abstract
Schistosomiasis remains an important public health issue, with a large number of cases reported across sub-Saharan Africa, and parts of Asia and Latin America. China was once highly endemic, but has made substantial progress and is moving towards elimination of schistosomiasis. Meanwhile, despite long-term, repeated, school-based chemotherapy in many African countries, more than 90% of all schistosomiasis cases are concentrated in Africa, and hence, this continent constitutes the key challenge for schistosomiasis control. Opportunities and issues for international collaboration in the fight against schistosomiasis are outlined with a focus on China's experiences, including the role of public health authorities and intersectoral collaboration, use of new and effective snail control approaches and diagnostic tools adapted to the specific stage of control, as well as the strengthening of risk mapping and surveillance-response mechanisms. Training courses targeting African governmental officials and professionals, coupled with field visits of African scientists and control programme managers to China, and vice versa, are considered important for improved schistosomiasis control and elimination. The crucial question remains whether the Chinese experience can be translated and applied in African countries to improve the effectiveness of health interventions and scale-up.
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Affiliation(s)
- Jing Xu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China
| | - Qing Yu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China
| | | | | | - Moussa Sacko
- National Institute for Research in Public Health, Ministry of Health, Bamako, Mali
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Dan-Dan Lin
- Jiangxi Provincial Institute of Parasitic Disease, Nanchang, China
| | - Kun Yang
- Jiangsu Provincial Institute of Schistosomiasis Control, Wuxi, China
| | - Li-Juan Zhang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China
| | - Qiang Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China
| | - Shi-Zhu Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China
| | - Jia-Gang Guo
- Department of Control of Neglected Tropical Diseases, WHO, Geneva, Switzerland
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, WHO Collaborating Center for Tropical Diseases, Shanghai, China.
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Sesay S, Paye J, Bah MS, McCarthy FM, Conteh A, Sonnie M, Hodges MH, Zhang Y. Schistosoma mansoni infection after three years of mass drug administration in Sierra Leone. Parasit Vectors 2014; 7:14. [PMID: 24401567 PMCID: PMC3895768 DOI: 10.1186/1756-3305-7-14] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/06/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Schistosoma mansoni was moderately-highly endemic in the northeast of Sierra Leone. The national neglected tropical disease control program started mass drug administration (MDA) with praziquantel (PZQ) in six districts in 2009 targeting primary school children only. The effort was scaled-up to seven districts in 2010 targeting school aged children (SAC) and at-risk adults. A cross-sectional sentinel site survey was conducted in 2012 after three rounds of MDA to evaluate the impact of the national program. METHODS Twenty-six (26) sentinel sites were randomly selected from the baseline mapping survey sites stratified according to the baseline prevalence into high, moderate or low endemic category. Fifty (50) school children (25 males and 25 females) were randomly selected per site. Fresh stool samples were examined in the field using the Kato Katz technique. The results were compared with the baseline data. RESULTS Program coverage of 94.8%, 77.1% and 81.7% was reported in 2009, 2010 and 2011 respectively. Independent monitoring in 2011 showed program coverage of 83.9%, not significantly different from the reported result in the same year. The overall prevalence of S. mansoni was 16.3% (95% CI: 14.4-18.4%) and mean intensity was 18.98 epg (95% CI: 11.46-26.50 epg) in 2012, representing 67.2% and 85.9% reduction from the baseline respectively. The proportion of moderately and heavily infected children was 3.3% and 1.2%, a significant reduction from 18.2% and 8.8% at baseline respectively. CONCLUSIONS Sierra Leone has maintained effective MDA coverage with PZQ since 2009. Three rounds of MDA led to a significant reduction of S. mansoni infection in the country. In line with the significant progress made in controlling schistosomiasis, the national treatment strategy has been reviewed and MDA will be expanded to include school age children in low endemicity districts with the new national objective for the elimination of schistosomiasis. Sierra Leone is well on its way to eliminate schistosomiasis as a public health problem.
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Affiliation(s)
| | | | | | | | | | | | - Mary H Hodges
- Helen Keller International, PO Box 352, Freetown, Sierra Leone.
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Predictive vs. empiric assessment of schistosomiasis: implications for treatment projections in Ghana. PLoS Negl Trop Dis 2013; 7:e2051. [PMID: 23505584 PMCID: PMC3591348 DOI: 10.1371/journal.pntd.0002051] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 12/21/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Mapping the distribution of schistosomiasis is essential to determine where control programs should operate, but because it is impractical to assess infection prevalence in every potentially endemic community, model-based geostatistics (MBG) is increasingly being used to predict prevalence and determine intervention strategies. METHODOLOGY/PRINCIPAL FINDINGS To assess the accuracy of MBG predictions for Schistosoma haematobium infection in Ghana, school surveys were evaluated at 79 sites to yield empiric prevalence values that could be compared with values derived from recently published MBG predictions. Based on these findings schools were categorized according to WHO guidelines so that practical implications of any differences could be determined. Using the mean predicted values alone, 21 of the 25 empirically determined 'high-risk' schools requiring yearly praziquantel would have been undertreated and almost 20% of the remaining schools would have been treated despite empirically-determined absence of infection - translating into 28% of the children in the 79 schools being undertreated and 12% receiving treatment in the absence of any demonstrated need. CONCLUSIONS/SIGNIFICANCE Using the current predictive map for Ghana as a spatial decision support tool by aggregating prevalence estimates to the district level was clearly not adequate for guiding the national program, but the alternative of assessing each school in potentially endemic areas of Ghana or elsewhere is not at all feasible; modelling must be a tool complementary to empiric assessments. Thus for practical usefulness, predictive risk mapping should not be thought of as a one-time exercise but must, as in the current study, be an iterative process that incorporates empiric testing and model refining to create updated versions that meet the needs of disease control operational managers.
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Hodges MH, Paye J, Koroma MM, Nyorkor ED, Fofonah I, Zhang Y. High level of Schistosoma mansoni infection in pre-school children in Sierra Leone highlights the need in targeting this age group for praziquantel treatment. Acta Trop 2012; 124:120-5. [PMID: 22820025 DOI: 10.1016/j.actatropica.2012.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 05/05/2012] [Accepted: 07/11/2012] [Indexed: 11/24/2022]
Abstract
BACKGROUND Schistosomiasis and soil-transmitted helminth (STH) infections are endemic in Sierra Leone. The consequences of these diseases to pre-school children are well understood. The national control program currently does not target this group of children for schistosomiasis, while mass drug administration (MDA) has been performed six monthly for STHs in children 12-59 months of age since 2006. METHODS To assist the national decision on MDA strategy to control schistosomiasis and STH, three cross-sectional surveys were conducted in pre-school children in 2009-2011 as part of routine surveillance performed in different areas and in different phases of MDA, including known 'Hard to Reach' villages where consistently poor coverage results were seen in recent MDA. Thirty 4-5 year-old children were randomly selected per site and a stool sample from each child was examined by Kato-Katz thick smear. Pooled data were analyzed for schistosomiasis and separate sets of data were presented for STHs. In total 61 sites were surveyed and a total of 1803 children were examined. RESULTS The overall prevalence and intensity of Schistosoma mansoni was 11.2% (95% CI 9.7-12.8) and 33.5 epg (95% CI 19.7-47.3). Relatively high level of infection was found in Kono (35.4% and 102.9 epg), Tonkolili (30.4% and 142.3 epg) and Koinadugu (20.8% and 47.0 epg). There were 8.1% of children 4-5 years old moderately or heavily infected with S. mansoni. Overall level of STH infections were generally low, with hookworm 8.4-22.8%, Ascaris lumbricoides 0.2-17.2%, and Trichuris trichiura 0.9-2.6% in three surveys. However, prevalence of hookworm and A. lumbricoides was relatively high in those hard-to-reach villages even two months after MDA. CONCLUSIONS Relatively high levels of S. mansoni infections were found in children aged 4-5 years old in Sierra Leone, in line with geographical distribution of the disease observed in older children in the country. The results suggest that this group of children should not be neglected further in the schistosomiasis MDA and a global guideline is needed. Overall prevalence of STH infection was relatively low. Although there was no baseline data for direct comparison, it did show a marked reduction in STH infections, compared with historical data. However, relatively higher prevalence in hard-to-reach villages suggests the difficulty and quality of implementing MDA in such difficult locations, and more efforts and perhaps different delivery strategies are needed in these locations to increase the quality of MDA.
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Combined spatial prediction of schistosomiasis and soil-transmitted helminthiasis in Sierra Leone: a tool for integrated disease control. PLoS Negl Trop Dis 2012; 6:e1694. [PMID: 22724034 PMCID: PMC3378624 DOI: 10.1371/journal.pntd.0001694] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 04/10/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND A national mapping of Schistosoma haematobium was conducted in Sierra Leone before the mass drug administration (MDA) with praziquantel. Together with the separate mapping of S. mansoni and soil-transmitted helminths, the national control programme was able to plan the MDA strategies according to the World Health Organization guidelines for preventive chemotherapy for these diseases. METHODOLOGY/PRINCIPAL FINDINGS A total of 52 sites/schools were selected according to prior knowledge of S. haematobium endemicity taking into account a good spatial coverage within each district, and a total of 2293 children aged 9-14 years were examined. Spatial analysis showed that S. haematobium is heterogeneously distributed in the country with significant spatial clustering in the central and eastern regions of the country, most prevalent in Bo (24.6% and 8.79 eggs/10 ml), Koinadugu (20.4% and 3.53 eggs/10 ml) and Kono (25.3% and 7.91 eggs/10 ml) districts. By combining this map with the previously reported maps on intestinal schistosomiasis using a simple probabilistic model, the combined schistosomiasis prevalence map highlights the presence of high-risk communities in an extensive area in the northeastern half of the country. By further combining the hookworm prevalence map, the at-risk population of school-age children requiring integrated schistosomiasis/soil-transmitted helminth treatment regimens according to the coendemicity was estimated. CONCLUSIONS/SIGNIFICANCE The first comprehensive national mapping of urogenital schistosomiasis in Sierra Leone was conducted. Using a new method for calculating the combined prevalence of schistosomiasis using estimates from two separate surveys, we provided a robust coendemicity mapping for overall urogenital and intestinal schistosomiasis. We also produced a coendemicity map of schistosomiasis and hookworm. These coendemicity maps can be used to guide the decision making for MDA strategies in combination with the local knowledge and programme needs.
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Tchuem Tchuenté LA, Kamwa Ngassam RI, Sumo L, Ngassam P, Dongmo Noumedem C, Nzu DDL, Dankoni E, Kenfack CM, Gipwe NF, Akame J, Tarini A, Zhang Y, Angwafo FF. Mapping of schistosomiasis and soil-transmitted helminthiasis in the regions of centre, East and West Cameroon. PLoS Negl Trop Dis 2012; 6:e1553. [PMID: 22413029 PMCID: PMC3295801 DOI: 10.1371/journal.pntd.0001553] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 01/18/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Schistosomiasis and soil-transmitted helminthiasis (STH) are widely distributed in Cameroon. Although mass drug administration (MDA) of mebendazole is implemented nationwide, treatment with praziquantel was so far limited to the three northern regions and few health districts in the southern part of Cameroon, based on previous mapping conducted 25 years ago. To update the disease distribution map and determine where treatment with praziquantel should be extended, mapping surveys were conducted in three of the seven southern regions of Cameroon, i.e. Centre, East and West. METHODOLOGY Parasitological surveys were conducted in April-May 2010 in selected schools in all 63 health districts of the three targeted regions, using appropriate research methodologies, i.e. Kato-Katz and urine filtration. PRINCIPAL FINDINGS The results showed significant variation of schistosomiasis and STH prevalence between schools, villages, districts and regions. Schistosoma mansoni was the most prevalent schistosome species, with an overall prevalence of 5.53%, followed by S. haematobium (1.72%) and S. guineensis (0.14%). The overall prevalence of schistosomiasis across the three regions was 7.31% (95% CI: 6.86-7.77%). The prevalence for Ascaris lumbricoides was 11.48 (95% CI: 10.93-12.04%), Trichuris trichiura 18.22% (95% CI: 17.56-18.90%) and hookworms 1.55% (95% CI: 1.35-1.78%), with an overall STH prevalence of 24.10% (95% CI: 23.36-24.85%) across the three regions. STH was more prevalent in the East region (46.57%; 95% CI: 44.41-48.75%) in comparison to the Centre (25.12; 95% CI: 24.10-26.17%) and West (10.49%; 95% CI: 9.57-11.51%) regions. CONCLUSIONS/SIGNIFICANCE In comparison to previous data, the results showed an increase of schistosomiasis transmission in several health districts, whereas there was a significant decline of STH infections. Based on the prevalence data, the continuation of annual or bi-annual MDA for STH is recommended, as well as an extension of praziquantel in identified moderate and high risk communities for schistosomiasis.
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Affiliation(s)
- Louis-Albert Tchuem Tchuenté
- National Programme for the Control of Schistosomiasis and Intestinal Helminthiasis, Ministry of Public Health, Yaoundé, Cameroon
- Laboratory of Parasitology and Ecology, University of Yaoundé I, Yaoundé, Cameroon
- Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
- * E-mail:
| | | | - Laurentine Sumo
- Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
| | - Pierre Ngassam
- Laboratory of Parasitology and Ecology, University of Yaoundé I, Yaoundé, Cameroon
| | | | | | - Esther Dankoni
- Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon
| | | | | | - Julie Akame
- Helen Keller International, Yaoundé, Cameroon
| | - Ann Tarini
- Helen Keller International, Yaoundé, Cameroon
| | - Yaobi Zhang
- Helen Keller International, Regional Office for Africa, Dakar, Senegal
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Hodges MH, Dada N, Warmsley A, Paye J, Bangura MM, Nyorkor E, Sonnie M, Zhang Y. Mass drug administration significantly reduces infection of Schistosoma mansoni and hookworm in school children in the national control program in Sierra Leone. BMC Infect Dis 2012; 12:16. [PMID: 22264258 PMCID: PMC3282666 DOI: 10.1186/1471-2334-12-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 01/22/2012] [Indexed: 11/17/2022] Open
Abstract
Background The first-ever round of school-based mass drug administration (MDA) with praziquantel together with mebendazole targeting school-aged children in endemic districts was conducted in 2009 by the National Neglected Tropical Diseases Control Program. To evaluate the impact of the treatment regimen, a cross-sectional sentinel site survey was conducted 6 months post-MDA. Methods Fifteen sentinel schools from six highly endemic districts (according to data from national and pre-MDA surveys) with Schistosoma mansoni affecting over 50% of the population, and moderate to high prevalence of hookworms (> 20%). Approximately 30 children aged 9-14 years were selected from each school and stool samples (one per student) were examined by the Kato-Katz method. Results The overall prevalence (and intensity) in these sentinel sites pre-MDA of S. mansoni was 69.0% (170.8 epg), hookworm: 41.7% (71.7 epg), Ascaris lumbricoides: 1.8% and Trichuris trichiura: 3.8%. Six months post MDA, the findings were S. mansoni: 38.2% (47.3 epg) and hookworm: 14.5% (8.7 epg), representing a reduction from pre-MDA levels of 44.6% (65.2%) and 72.3% (87.9%) respectively. The proportion of children who were moderately or heavily infected with S. mansoni fell from 35.6% pre MDA to 9.9% post MDA. Conclusions Significant reduction in S. mansoni and hookworm infection was achieved by this first round MDA in school-going children in Sierra Leone. This reduction in infection burden can potentially contribute to a reduction of morbidity, such as anaemia, in these children.
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Affiliation(s)
- Mary H Hodges
- Helen Keller International, PO Box 369, Freetown, Sierra Leone.
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