Mapping of Schistosomiasis and Soil-Transmitted Helminthiasis in the Regions of Centre, East and West Cameroon

Schistosomiasis and soil-transmitted helminthiasis (STH) are a major public health problem in Cameroon. The national control strategy of these diseases was based on historical data collected 25 years ago, which might be outdated in some situations due to several factors including control activities, improved or degraded sanitation and hygiene, socio-economic improvement and disease transmission dynamics. To help planning, improving control strategies and evaluation of control activities, there was a need to update the distribution of schistosomiasis and STH. We conducted parasitological surveys in three regions of Cameroon, i.e. Centre, East and West. Our results showed a significant decrease of STH infection prevalence and intensities in all these three regions, in comparison to previous mapping data, with an overall decline of prevalence from 81.1–93% to 10.5–46.6%. These results show the positive impact of annual deworming campaigns, and illustrate the progressive success of the national programme for the control of schistosomiasis and STH in Cameroon. Furthermore, our results showed an increase of the number of high transmission foci of schistosomiasis, and allowed identifying new health districts requiring mass treatment with praziquantel, and those where deworming should be reinforced

Evaluation of circulating cathodic antigen (CCA) urine-tests for diagnosis of Schistosoma mansoni infection in Cameroon.

BACKGROUND The Kato-Katz is the most common diagnostic method for Schistosoma mansoni infection. However, the day-to-day variability in host egg-excretion and its low detection sensitivity are major limits for its use in low transmission zones and after widespread chemotherapy. We evaluated the accuracy of circulating cathodic antigen (CCA) urine-assay as a diagnostic tool of S. mansoni. In comparison, a low sensitive CCA test (CCA-L) was assessed. METHODOLOGY THE STUDY WAS CONDUCTED IN THREE SETTINGS: two foci with single S. mansoni infections (settings A and B), and one mixed S. mansoni - S. haematobium focus (setting C). Stool and urine samples were collected from school-children on three consecutive days. Triplicate Kato-Katz readings were performed per stool sample. Each urine sample was tested with one CCA and only the first urine sample was subjected to CCA-L. Urine samples were also examined for S. haematobium eggs using the filtration method and for microhaematuria using urine reagent strips. Overall, 625 children provided three stool and three urine samples. PRINCIPAL FINDINGS Considering nine Kato-Katz thick smears as 'reference' diagnostic test, the prevalence of S. mansoni was 36.2%, 71.8% and 64.0% in settings A, B and C, respectively. The prevalence of S. haematobium in setting C was 12.0%. The sensitivities of single Kato-Katz, CCA and CCA-L from the first stool or urine samples were 58%, 82% and 46% in setting A, 56.8%, 82.4% and 68.8% in setting B, and 49.0%, 87.7% and 55.5% in setting C. The respective specificities were 100%, 64.7% and 100%; 100%, 62.3% and 91.3%; and 100%, 42.5% and 92.0%. Mixed infection with S. haematobium did not influence the CCA test results for S. mansoni diagnosis. CONCLUSIONS/SIGNIFICANCE Urine CCA revealed higher sensitivity than CCA-L and triplicate Kato-Katz, and produced similar prevalence as nine Kato-Katz. It seems an attractive method for S. mansoni diagnosis

Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of different tests for the diagnosis of <i>S.mansoni</i>.

<p>Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of different tests for the diagnosis of <i>S.mansoni</i>.</p

Correlation between the prevalence of CCA test and the intensities of <i>S. mansoni</i> infections.

<p>Correlation between the prevalence of CCA test and the intensities of <i>S. mansoni</i> infections.</p

Agreement between different techniques for the diagnosis of <i>S. mansoni</i> infections.

*<p>k<0 indicating no agreement, k = 0–0.2 indicating poor agreement, k = 0.21–0.4 indicating fair agreement, k = 0.41–0.6 indicating moderate agreement, k = 0.61–0.8 indicating substantial agreement, and k = 0.81–1 indicating almost perfect agreement.</p

Correlation between <i>S. mansoni</i> infection intensities and CCA results.

<p>The prevalences of CCA (single CCA, triple CCA and CCA-L) are affected by the abundance of <i>S. mansoni</i> infection (stratified by intensity classes). A = setting 1, B = setting 2, C = setting 3, D = All settings A-B-C.</p

Prevalence of <i>S. mansoni</i> and <i>S. haematobium</i> infections according to each diagnostic test and stratified by epidemiological setting.

<p>Setting A = Yaoundé, Setting B = Makénéné, Setting C = Njombé.</p

Comparison of prevalence of schistosomiasis and STH between 1980s and 2010.

<p>Note:</p><p>*Figures in brackets represent the 95% confidence intervals.</p

Prevalence of schistosomiasis and STH by age in the three surveyed regions in Cameroon.

<p>A few outliers below 5 or above 17 years old are not plotted.</p