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Accuracy of different diagnostic techniques for Schistosoma haematobium to estimate treatment needs in Zimbabwe: Application of a hierarchical Bayesian egg count model.

ABSTRACT: BACKGROUND:Treatment needs for Schistosoma haematobium are commonly evaluated using urine filtration with detection of parasite eggs under a microscope. A common symptom of S. haematobium is hematuria, the passing of blood in urine. Hence, the use of hematuria-based diagnostic techniques as a proxy for the assessment of treatment needs has been considered. This study evaluates data from a national survey in Zimbabwe, where three hematuria-based diagnostic techniques, that is microhematuria, macrohematuria, and an anamnestic questionnaire pertaining to self-reported blood in urine, have been included in addition to urine filtration in 280 schools across 70 districts. METHODOLOGY:We developed an egg count model, which evaluates the infection intensity-dependent sensitivity and the specificity of each diagnostic technique without relying on a 'gold' standard. Subsequently, we determined prevalence thresholds for each diagnostic technique, equivalent to a 10% urine filtration-based prevalence and compared classification of districts according to treatment strategy based on the different diagnostic methods. PRINCIPAL FINDINGS:A 10% urine filtration prevalence threshold corresponded to a 17.9% and 13.3% prevalence based on questionnaire and microhematuria, respectively. Both the questionnaire and the microhematuria showed a sensitivity and specificity of more than 85% for estimating treatment needs at the above thresholds. For diagnosis at individual level, the questionnaire showed the highest sensitivity (70.0%) followed by urine filtration (53.8%) and microhematuria (52.2%). CONCLUSIONS/SIGNIFICANCE:The high sensitivity and specificity of a simple questionnaire to estimate treatment needs of S. haematobium suggests that it can be used as a rapid, low-cost method to estimate district prevalence. Our modeling approach can be expanded to include setting-dependent specificity of the technique and should be assessed in relation to other diagnostic methods due to potential cross-reaction with other diseases.

SUBMITTER: Midzi N

PROVIDER: S-EPMC7462259 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Accuracy of different diagnostic techniques for Schistosoma haematobium to estimate treatment needs in Zimbabwe: Application of a hierarchical Bayesian egg count model.

Midzi Nicholas N Bärenbold Oliver O Manangazira Portia P Phiri Isaac I Mutsaka-Makuvaza Masceline J MJ Mhlanga Gibson G Utzinger Jürg J Vounatsou Penelope P

PLoS neglected tropical diseases 20200820 8

<h4>Background</h4>Treatment needs for Schistosoma haematobium are commonly evaluated using urine filtration with detection of parasite eggs under a microscope. A common symptom of S. haematobium is hematuria, the passing of blood in urine. Hence, the use of hematuria-based diagnostic techniques as a proxy for the assessment of treatment needs has been considered. This study evaluates data from a national survey in Zimbabwe, where three hematuria-based diagnostic techniques, that is microhematur ...[more]

PMID: 32817650

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Project description:ObjectivesThe study assessed associations between Schistosoma haematobium infection (presence of parasite eggs in urine or hematuria) and self-reported metrics (macrohematuria, fetching surface water, or swimming) to evaluate their performance as proxies of infection in presence of regular preventive chemotherapy. It also examined community water characteristics (safe water access, surface water access, and groundwater quality) to provide context for schistosomiasis transmission in different types of communities and propose interventions.MethodsLogistic regression was used to assess the associations between the various measured and self-reported metrics in a sample of 897 primary school children in 30 rural Ghanaian communities. Logistic regression was also used to assess associations between community water characteristics, self-reported water-related behaviors and S. haematobium infection. Communities were subsequently categorized as candidates for three types of interventions: provision of additional safe water sources, provision of groundwater treatment, and health education about water-related disease risk, depending on their water profile.ResultsMicrohematuria presence measured with a reagent strip was a good proxy of eggs in urine at individual (Kendall's τb = 0.88, p < 0.001) and at school-aggregated (Spearman's rs = 0.96, p < 0.001) levels. Self-reported macrohematuria and swimming were significantly associated (p < 0.05) with egg presence, but self-reported fetching was not. Of the community water characteristics, greater surface water access and presence of groundwater quality problems were significantly associated with increased likelihood of fetching, swimming, and S. haematobium infection. Access to improved water sources did not exhibit an association with any of these outcomes.ConclusionsThe study illustrates that in presence of regular school-based treatment with praziquantel, microhematuria assessed via reagent strips remains an adequate proxy for S. haematobium infection in primary schoolchildren. Community water profiles, in combination with self-reported water-related behaviors, can help elucidate reasons for some endemic communities continuing to experience ongoing transmission and tailor interventions to these local contexts to achieve sustainable control.

Dataset Information

Accuracy of different diagnostic techniques for Schistosoma haematobium to estimate treatment needs in Zimbabwe: Application of a hierarchical Bayesian egg count model.

Publications

Accuracy of different diagnostic techniques for Schistosoma haematobium to estimate treatment needs in Zimbabwe: Application of a hierarchical Bayesian egg count model.

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