{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T16:41:11Z","timestamp":1790095271948,"version":"4.0.1"},"reference-count":31,"publisher":"American Society of Tropical Medicine and Hygiene","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2018,5,9]]},"abstract":"<jats:p>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 <jats:italic>Schistosoma mansoni<\/jats:italic>. At baseline and for the following four consecutive years, between 897 and 1,440 school children in Grades 1\u201312 were enrolled and evaluated by Kato-Katz for <jats:italic>S. mansoni<\/jats:italic> and soil-transmitted helminths (STH), followed by annual MDA with PZQ and albendazole. Four annual rounds of MDA with PZQ were associated with reduced <jats:italic>S. mansoni<\/jats:italic> prevalence in all school children (44.7\u201314.0%; <jats:italic>P<\/jats:italic> &lt; 0.001) and mean intensity of infection by 91% (90.4 to 8.1 eggs per gram [epg] of stool; <jats:italic>P<\/jats:italic> &lt; 0.001). Prevalence of high-intensity infection (\u2265 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\u201312) 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.<\/jats:p>","DOI":"10.4269\/ajtmh.17-0908","type":"journal-article","created":{"date-parts":[[2018,3,13]],"date-time":"2018-03-13T07:00:19Z","timestamp":1520924419000},"page":"1397-1402","source":"Crossref","is-referenced-by-count":20,"title":["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"],"prefix":"10.4269","volume":"98","author":[{"given":"Bernard O.","family":"Abudho","sequence":"first","affiliation":[{"name":"Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;"},{"name":"Department of Biomedical Sciences, School of Public Health, Maseno University, Maseno, Kenya;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eric M.","family":"Ndombi","sequence":"additional","affiliation":[{"name":"Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;"},{"name":"Department of Pathology, Kenyatta University, Nairobi, Kenya;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bernard","family":"Guya","sequence":"additional","affiliation":[{"name":"Department of Biomedical Sciences, School of Public Health, Maseno University, Maseno, Kenya;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer M.","family":"Carter","sequence":"additional","affiliation":[{"name":"Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diana K.","family":"Riner","sequence":"additional","affiliation":[{"name":"Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nupur","family":"Kittur","sequence":"additional","affiliation":[{"name":"Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diana M. S.","family":"Karanja","sequence":"additional","affiliation":[{"name":"Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W. Evan","family":"Secor","sequence":"additional","affiliation":[{"name":"Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Daniel G.","family":"Colley","sequence":"additional","affiliation":[{"name":"Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia;"},{"name":"Department of Microbiology, University of Georgia, Athens, Georgia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2795","reference":[{"key":"b1","series-title":"Lancet","first-page":"2253","article-title":"Human schistosomiasis","volume":"383","author":"Colley","year":"2014"},{"key":"b2","author":"WHO","year":"2012"},{"key":"b3","series-title":"Acta Trop","first-page":"125","article-title":"Quantification of clinical morbidity associated with schistosome infection in sub-Saharan Africa","volume":"86","author":"van der Werf","year":"2003"},{"key":"b4","series-title":"Wkly Epidemiol Rec","first-page":"81","article-title":"Schistosomiasis: number of people treated in 2011","volume":"88","author":"WHO","year":"2013"},{"key":"b5","author":"GAHI","year":"2010"},{"key":"b6","series-title":"Am J Trop Med Hyg","first-page":"318","article-title":"Geographic distribution of schistosomiasis and soil-transmitted helminths in western Kenya: implications for anthelminthic mass treatment","volume":"69","author":"Handzel","year":"2003"},{"key":"b7","series-title":"PLoS One","first-page":"e71635","article-title":"Use of geospatial modeling to predict Schistosoma mansoni prevalence in Nyanza Province, Kenya","volume":"8","author":"Woodhall","year":"2013"},{"key":"b8","series-title":"WHO Tech Rep Ser","first-page":"1","article-title":"Prevention and control of schistosomiasis and soil-transmitted helminthiasis: report of a WHO expert committee","volume":"912","author":"WHO","year":"2002"},{"key":"b9","series-title":"Bull World Health Organ","first-page":"91","article-title":"Impact of a national helminth control programme on infection and morbidity in Ugandan schoolchildren","volume":"85","author":"Kabatereine","year":"2007"},{"key":"b10","series-title":"J Infect Dis","first-page":"659","article-title":"Schistosoma haematobium infection and morbidity before and after large-scale administration of praziquantel in Burkina Faso","volume":"196","author":"Koukounari","year":"2007"},{"key":"b11","series-title":"Parasit Vectors","first-page":"182","article-title":"Integrated community-directed intervention for schistosomiasis and soil transmitted helminths in western Kenya\u2014a pilot study","volume":"5","author":"Mwinzi","year":"2012"},{"key":"b12","series-title":"Acta Trop","first-page":"161","article-title":"The impact of chemotherapy on morbidity due to schistosomiasis","volume":"86","author":"Richter","year":"2003"},{"key":"b13","author":"WHO","year":"2013"},{"key":"b14","series-title":"Am J Trop Med Hyg","first-page":"3","article-title":"The efficacy of permethrin-treated bed nets on child mortality and morbidity in western Kenya I. 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