{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T12:17:40Z","timestamp":1789906660588,"version":"4.0.1"},"reference-count":0,"publisher":"Cambridge University Press (CUP)","issue":"2","license":[{"start":{"date-parts":[[1997,2,1]],"date-time":"1997-02-01T00:00:00Z","timestamp":854755200000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/www.cambridge.org\/core\/terms"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Parasitology"],"published-print":{"date-parts":[[1997,2]]},"abstract":"<jats:p><jats:italic>Schistosoma mansoni<\/jats:italic> egg counts by faecal examination\n vary \n\nconsiderably \n\nand are not very sensitive, so prevalences are \n\nunderestimated. The distribution of egg counts can adequately be described\n by a \n\nstochastic model which distinguishes \n\nvariation in counts between persons and variation in repeated counts within\n a \n\nperson. Based on this model a pocket chart \n\nhas been developed which predicts the proportion of individuals harbouring\n at \n\nleast 1 <jats:italic>S. mansoni<\/jats:italic> worm pair \u2013 the \u2018true \n\nprevalence\u2019 \u2013 from a simple single survey prevalence and geometric\n mean egg \n\ncount (using common duplicate 25 mg \n\nKato\u2013Katz smears). The current paper describes the validation of\n this chart \n\nby comparing predicted true prevalences with \n\nprevalences observed after 5\u20137 repeated Kato\u2013Katz faecal examinations\n \n\n(Burundi), by examination of a large quantity of \n\nstool using the Visser filter (Brazil) or a selective sedimentation\u2013filtration\n \n\nmethod (Surinam). Because 5\u20137 repeated \n\nexaminations do not suffice to measure all infections, predictions have\n been \n\nmade of the cumulative proportion positives \n\nover 5\u20137 surveys \u2013 the \u2018approximate true prevalence\u2019\n \u2013 as well. After dividing \n\nthe data into age groups, 12 different subsets \n\nwere considered for validation. In all 12 cases, predicted true prevalences\n (or \n\napproximate true prevalences for the Burundi \n\ndata) agree well with those observed. The overall agreement depends only\n slightly \n\non the assumed relationship between \n\nworm numbers and mean egg counts, with a good fit for a productivity between\n 0\u00b78 \n\nand 4\u00b74 eggs per gramme faeces (EPG) \n\nper worm pair (WP). This interval includes the most plausible value from\n the \n\nliterature, i.e. 1\u00b70 EPG\/WP, which has been \n\napplied in the initial pocket chart. These findings support the validity\n of the \n\nchart to predict true prevalences for a wide \n\nrange of productivity assumptions, and reinforces the applicability of\n its \n\nunderlying stochastic model to describe egg count \n\nvariation. However, as predictions appear to vary importantly when using\n only \n\npart of the data, it is also concluded that \n\nthe pocket chart never compensates for limited validity of initial single\n \n\nsurvey prevalences and geometric means in consequence of small sample sizes.<\/jats:p>","DOI":"10.1017\/s0031182096008207","type":"journal-article","created":{"date-parts":[[2002,7,27]],"date-time":"2002-07-27T09:30:22Z","timestamp":1027762222000},"page":"113-121","source":"Crossref","is-referenced-by-count":52,"title":["Validation of a chart to estimate true <i>Schistosoma \n\nmansoni<\/i> prevalences from simple egg counts"],"prefix":"10.1017","volume":"114","author":[{"given":"S. J.","family":"DE VLAS","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D.","family":"ENGELS","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. L. T.","family":"RABELLO","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B. F. J.","family":"OOSTBURG","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L.","family":"VAN LIESHOUT","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. M.","family":"POLDERMAN","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"G. J.","family":"VAN OORTMARSSEN","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. D. F.","family":"HABBEMA","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B.","family":"GRYSEELS","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"56","published-online":{"date-parts":[[1997,2,1]]},"container-title":["Parasitology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.cambridge.org\/core\/services\/aop-cambridge-core\/content\/view\/S0031182096008207","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,5,12]],"date-time":"2019-05-12T15:09:44Z","timestamp":1557673784000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.cambridge.org\/core\/product\/identifier\/S0031182096008207\/type\/journal_article"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1997,2]]},"references-count":0,"journal-issue":{"issue":"2","published-print":{"date-parts":[[1997,2]]}},"alternative-id":["S0031182096008207"],"URL":"https:\/\/doi.org\/10.1017\/s0031182096008207","relation":{},"ISSN":["0031-1820","1469-8161"],"issn-type":[{"value":"0031-1820","type":"print"},{"value":"1469-8161","type":"electronic"}],"subject":[],"published":{"date-parts":[[1997,2]]}}}