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Urogenital schistosomiasis elimination in Zanzibar : accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections

Knopp, Stefanie and Ame, Shaali M. and Hattendorf, Jan and Ali, Said M. and Khamis, Iddi S. and Bakar, Faki and Khamis, Mwanaidi A. and Person, Bobbie and Kabole, Fatma and Rollinson, David. (2018) Urogenital schistosomiasis elimination in Zanzibar : accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections. Parasites and Vectors, 11. p. 552.

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Abstract

Urine filtration and microhaematuria reagent strips are basic standard diagnostic methods to detect urogenital schistosomiasis. We assessed their accuracy for the diagnosis of light intensity infections with Schistosoma haematobium as they occur in individuals living in Zanzibar, an area targeted for interruption of transmission.; Urine samples were collected from children and adults in surveys conducted annually in Zanzibar from 2013 through 2016 and examined with the urine filtration method to count S. haematobium eggs and with the reagent strip test (Hemastix) to detect microhaematuria as a proxy for infection. Ten percent of the urine filtration slides were read twice. Sensitivity was calculated for reagent strips, stratified by egg counts reflecting light intensity sub-groups, and kappa statistics for the agreement of urine filtration readings.; Among the 39,207 and 18,155 urine samples examined from children and adults, respectively, 5.4% and 2.7% were S. haematobium egg-positive. A third (34.7%) and almost half (46.7%) of the egg-positive samples from children and adults, respectively, had ultra-low counts defined as 1-5 eggs per 10 ml urine. Sensitivity of the reagent strips increased significantly for each unit log10 egg count per 10 ml urine in children (odds ratio, OR: 4.7; 95% confidence interval, CI: 4.0-5.7; P < 0.0001) and adults (OR: 2.6; 95% CI: 1.9-3.7, P < 0.0001). Sensitivity for diagnosing ultra-light intensity infections was very low in children (50.1%; 95% CI: 46.5-53.8%) and adults (58.7%; 95% CI: 51.9-65.2%). Among the 4477 and 1566 urine filtration slides read twice from children and adults, most were correctly identified as negative or positive (kappa = 0.84 for children and kappa = 0.81 for adults). However, 294 and 75 slides had discrepant results and were positive in only one of the two readings. The majority of these discrepant slides (76.9% of children and 84.0% of adults) had counts of 1-5 eggs per 10 ml urine.; We found that many individuals infected with S. haematobium in Zanzibar excrete > 5 eggs per 10 ml urine. These ultra-light infections impose a major challenge for accurate diagnosis. Next-generation diagnostic tools to be used in settings where interruption of transmission is the goal should reliably detect infections with ≤ 5 eggs per 10 ml urine.; ISRCTN, ISRCTN48837681 . Registered 05 September 2012 - Retrospectively registered.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Eco System Health Sciences > Health Impact Assessment (Utzinger)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Human and Animal Health > One Health (Zinsstag)
UniBasel Contributors:Knopp, Stefanie and Hattendorf, Jan
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:BioMed Central
ISSN:1756-3305
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:22 Nov 2018 12:42
Deposited On:22 Nov 2018 12:42

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