Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections
Abstract Background 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,...
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| Format: | Article |
| Language: | English |
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BMC
2018-10-01
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| Series: | Parasites & Vectors |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13071-018-3136-6 |
| _version_ | 1830416949891301376 |
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| author | Stefanie Knopp Shaali M Ame Jan Hattendorf Said M Ali Iddi S Khamis Faki Bakar Mwanaidi A Khamis Bobbie Person Fatma Kabole David Rollinson |
| author_facet | Stefanie Knopp Shaali M Ame Jan Hattendorf Said M Ali Iddi S Khamis Faki Bakar Mwanaidi A Khamis Bobbie Person Fatma Kabole David Rollinson |
| author_sort | Stefanie Knopp |
| collection | DOAJ |
| description | Abstract Background 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. Methods 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. Results 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. Conclusions We found that many individuals infected with S. haematobium in Zanzibar excrete less than 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. Trial Registration ISRCTN, ISRCTN48837681. Registered 05 September 2012 - Retrospectively registered. |
| first_indexed | 2024-12-20T21:33:19Z |
| format | Article |
| id | doaj.art-29698b7af0b14309ae2e94baedee902d |
| institution | Directory Open Access Journal |
| issn | 1756-3305 |
| language | English |
| last_indexed | 2024-12-20T21:33:19Z |
| publishDate | 2018-10-01 |
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| spelling | doaj.art-29698b7af0b14309ae2e94baedee902d2022-12-21T19:26:00ZengBMCParasites & Vectors1756-33052018-10-0111111110.1186/s13071-018-3136-6Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infectionsStefanie Knopp0Shaali M Ame1Jan Hattendorf2Said M Ali3Iddi S Khamis4Faki Bakar5Mwanaidi A Khamis6Bobbie Person7Fatma Kabole8David Rollinson9Swiss Tropical and Public Health InstitutePublic Health Laboratory Ivo-de CarneriSwiss Tropical and Public Health InstitutePublic Health Laboratory Ivo-de CarneriNeglected Diseases Programme, Ministry of HealthPublic Health Laboratory Ivo-de CarneriNeglected Diseases Programme, Ministry of HealthSchistosomiasis Consortium for Operational Research and Evaluation, 145 Coverdell Center, The University of GeorgiaNeglected Diseases Programme, Ministry of HealthWolfson Wellcome Biomedical Laboratories, Department of Life Sciences, Natural History MuseumAbstract Background 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. Methods 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. Results 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. Conclusions We found that many individuals infected with S. haematobium in Zanzibar excrete less than 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. Trial Registration ISRCTN, ISRCTN48837681. Registered 05 September 2012 - Retrospectively registered.http://link.springer.com/article/10.1186/s13071-018-3136-6ControlDiagnosisEliminationMacrohaematuriaMicrohaematuriaReagent strip |
| spellingShingle | Stefanie Knopp Shaali M Ame Jan Hattendorf Said M Ali Iddi S Khamis Faki Bakar Mwanaidi A Khamis Bobbie Person Fatma Kabole David Rollinson Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections Parasites & Vectors Control Diagnosis Elimination Macrohaematuria Microhaematuria Reagent strip |
| title | Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections |
| title_full | Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections |
| title_fullStr | Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections |
| title_full_unstemmed | Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections |
| title_short | Urogenital schistosomiasis elimination in Zanzibar: accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity Schistosoma haematobium infections |
| title_sort | urogenital schistosomiasis elimination in zanzibar accuracy of urine filtration and haematuria reagent strips for diagnosing light intensity schistosoma haematobium infections |
| topic | Control Diagnosis Elimination Macrohaematuria Microhaematuria Reagent strip |
| url | http://link.springer.com/article/10.1186/s13071-018-3136-6 |
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