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      Impact of Four Years of Annual Mass Drug Administration on Prevalence and Intensity of Schistosomiasis among Primary and High School Children in Western Kenya: A Repeated Cross-Sectional Study


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          Schistosomiasis remains a major public health problem in Kenya. The World Health Organization recommends preventive chemotherapy with praziquantel (PZQ) to control morbidity due to schistosomiasis. Morbidity is considered linked to intensity of infection, which along with prevalence is used to determine the frequency of mass drug administration (MDA) to school-age children. We determined the impact of annual school-based MDA on children across all primary and high school years using a repeated cross-sectional study design in five schools near Lake Victoria in western Kenya, an area endemic for Schistosoma mansoni. At baseline and for the following four consecutive years, between 897 and 1,440 school children in Grades 1–12 were enrolled and evaluated by Kato-Katz for S. mansoni and soil-transmitted helminths (STH), followed by annual MDA with PZQ and albendazole. Four annual rounds of MDA with PZQ were associated with reduced S. mansoni prevalence in all school children (44.7–14.0%; P < 0.001) and mean intensity of infection by 91% (90.4 to 8.1 eggs per gram [epg] of stool; P < 0.001). Prevalence of high-intensity infection (≥ 400 epg) decreased from 6.8% at baseline to 0.3% by the end of the study. Soil-transmitted helminth infections, already low at baseline, also decreased significantly over the years. In this high prevalence area, annual school-based MDA with high coverage across all Grades (1–12) resulted in rapid and progressive declines in overall prevalence and intensity of infection. This decrease was dramatic in regard to heavy infections in older school-attending children.

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          Reassessment of the cost of chronic helmintic infection: a meta-analysis of disability-related outcomes in endemic schistosomiasis.

          Schistosomiasis is one of the world's most prevalent infections, yet its effect on the global burden of disease is controversial. Published disability-adjusted life-year (DALY) estimates suggest that the average effect of schistosome infection is quite small, although this is disputed. To develop an evidenced-based reassessment of schistosomiasis-related disability, we did a systematic review of data on disability-associated outcomes for all forms of schistosomiasis. We did structured searches using EMBASE, PUBMED, and Cochrane electronic databases. Published bibliographies were manually searched, and unpublished studies were obtained by contacting research groups. Reports were reviewed and abstracted independently by two trained readers. All randomised and observational studies of schistosomiasis morbidity were eligible for inclusion. We calculated pooled estimates of reported disability-related effects using weighted odds ratios for categorical outcomes and standardised mean differences for continuous data. 482 published or unpublished reports (March, 1921, to July, 2002) were screened. Of 135 selected for inclusion, 51 provided data for performance-related symptoms, whereas 109 reported observed measures of disability-linked morbidities. Schistosomiasis was significantly associated with anaemia, chronic pain, diarrhoea, exercise intolerance, and undernutrition. By contrast with WHO estimates of 0.5% disability weight assigned to schistosomiasis, 2-15% disability seems evident in different functional domains of a person with schistosomiasis. This raised estimate, if confirmed in formal patient-preference studies, indicates a need to reassess our priorities for treating this silent pandemic of schistosomiasis.
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            Impact of a national helminth control programme on infection and morbidity in Ugandan schoolchildren

            OBJECTIVE: We aimed to assess the health impact of a national control programme targeting schistosomiasis and intestinal nematodes in Uganda, which has provided population-based anthelmintic chemotherapy since 2003. METHODS: We conducted longitudinal surveys on infection status, haemoglobin concentration and clinical morbidity in 1871 randomly selected schoolchildren from 37 schools in eight districts across Uganda at three time points - before chemotherapy and after one year and two years of annual mass chemotherapy. FINDINGS: Mass treatment with praziquantel and albendazole led to a significant decrease in the intensity of Schistosoma mansoni - 70% (95% confidence interval (CI): 66-73%) after one year and 82% (95% CI: 80-85%) after two years of treatment. Intensity of hookworm infection also decreased (75% and 93%; unadjusted). There was a significant increase in haemoglobin concentration after one (0.135 g/dL (95% CI: 0.126-0.144)) and two years (0.303 g/dL (95% CI: 0.293-0.312)) of treatment, and a significant decrease in signs of early clinical morbidity. The impact of intervention on S. mansoni prevalence and intensity was similar to that predicted by mathematical models of the impact of chemotherapy on human schistosomiasis. Improvements in haemoglobin concentration were greatest among children who were anaemic or harbouring heavy S. mansoni infection at baseline. CONCLUSION: Anthelmintic treatment delivered as part of a national helminth control programme can decrease infection and morbidity among schoolchildren and improve haemoglobin concentration.
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              Geographic distribution of schistosomiasis and soil-transmitted helminths in Western Kenya: implications for anthelminthic mass treatment.

              A survey of 1,246 children 10-12 years old in 32 primary schools in Kenya near Lake Victoria was conducted to determine prevalence and distribution of schistosome and geohelminth infections. Stool and urine samples were collected and examined for eggs of Schistosoma mansoni, S. haematobium, and intestinal helminths. A questionnaire was used to obtain demographic information and to quantify exposure to surface waters. Houses, schools, and water sources were mapped using a geographic information system. The mean school prevalence of S. mansoni infection was 16.3% (range = 0-80%). Proximity to the lake (r = 0.89, P < 0.001) and contact with lake water were associated with infection, as were specific water-related activities including swimming, fishing, and collecting water. Sixty-three percent of students were infected with one or more other geohelminths and these infections were more homogenously distributed. The separate distributions of schistosome and geohelminth infections have important implications for combined mass-treatment programs.

                Author and article information

                Am J Trop Med Hyg
                Am. J. Trop. Med. Hyg
                The American Journal of Tropical Medicine and Hygiene
                The American Society of Tropical Medicine and Hygiene
                May 2018
                12 March 2018
                12 March 2018
                : 98
                : 5
                : 1397-1402
                [1 ]Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;
                [2 ]Department of Biomedical Sciences, School of Public Health, Maseno University, Maseno, Kenya;
                [3 ]Department of Pathology, Kenyatta University, Nairobi, Kenya;
                [4 ]Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia;
                [5 ]Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia,
                [6 ]Department of Microbiology, University of Georgia, Athens, Georgia
                Author notes
                [* ]Address correspondence to Daniel G. Colley, 500 DW Brooks Dr., Center for Tropical and Emerging Global Diseases; Room 330B Coverdell Center, Athens, GA 30602. E-mail: dcolley@ 123456uga.edu

                Financial support: Funding support was provided by the NIH Grant R01AI53695.

                Authors’ addresses: Bernard O. Abudho, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya, and Department of Biomedical Sciences, Maseno University, Maseno, Nyanza, Kenya, E-mail: bernabu002@ 123456gmail.com . Eric M. Ndombi, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya, and Department of Pathology, Kenyatta University, Nairobi, Kenya, E-mail: emakuto@ 123456gmail.com . Bernard Guya, Maseno University, Maseno, Nyanza, Kenya, E-mail: guyah.bernard@ 123456yahoo.com . Jennifer M. Carter, Diana K. Riner, Nupur Kittur, and Daniel G. Colley, Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA, E-mails: jenmcar@ 123456gmail.com , dianariner@ 123456yahoo.com , nkittur@ 123456uga.edu , and dcolley@ 123456uga.edu . Diana M. S. Karanja, Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya, E-mail: diana@ 123456cohesu.com . W. Evan Secor, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, E-mail: was4@ 123456cdc.gov .

                © The American Society of Tropical Medicine and Hygiene

                This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                Page count
                Pages: 6

                Infectious disease & Microbiology
                Infectious disease & Microbiology


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