Evaluation of field recognizable morbidity indicators of Schistosoma haematobium infection among primary school children in Ghana

Abstract

Aim - This study was a retrospective evaluation of morbidity indicators and the use of questionnaire in decisions that relate to Schistosoma haematobium infection control among primary school children in Ghana. Materials and Methods — In all, 417 pupils in three primary schools (Kasseh sub-District, Dangme East District, Ghana), provided urine samples, which were examined for S. haematobium ova. The study utilized a structured questionnaire, the Urit 10V multi-stick urine reagent strips and the filtration method. Results — Overall, prevalence by microscopy was 20.9% (requires targeted treatment once every two years), and was higher (14.0%) among the 10-15 years age group (χ2=22.44, p<0.001). The lowest prevalence was among the <6 (0.5%, 2/417) and ≥19 (1.4%, 6/417) years age groups. There was no significant difference in prevalence among females (7.9%, 33/417) and males (12.9%, 54/417) (χ2=2.58, p=0.108). Self-reported haematuria was 43.2% (targeted treatment once a year). There was a significant difference between female (16.1%, 67/417) and male (27.1%, 113/417) responses to self-reported haematuria (χ2=4.170, p<0.001). A lower consolidated mean prevalence of 11.7% was estimated among pupils who had ova in their urine and also exhibited three morbidity indicators (haematuria, leucocyturia and proteinuria). Combined and averaged sensitivity and specificity estimations (sensitivity = 55.4%, specificity = 67.8%, Positive Predictive Value (PPV) = 53.4%, Negative Predictive Value (NPV) = 64.2%) of these morbidity indicators, was insufficient in equalizing the reliability of ova quantification. With the exception of leucocyturia, which was common among all pupils, 28.75% (25/87) of the infected individuals did not have any form of haematuria or proteinuria. Out of these, one pupil had heavy ova intensity (80 eggs/10ml of urine) while the remaining 24 had low ova intensity infection (1-44 eggs/10ml of urine). Questionnaire correctly identified 56.3% of pupils with S. haematobium ova in their urine, also reporting bloody urine (PPV=27.2%; NPV=84.0%). It also identified 49.4% of pupils with ova, reporting painful urination (PPV=26.1%, NPV=82.5%). Conclusion — This study emphasizes the relevance of evaluating the criteria for interpretation of morbidity indicators, prior to their field application. Questionnaire use remains key for surveillance purposes, to determine the presence of the infection in an area. Future studies should consolidate similar data elsewhere in Ghana for a better understanding of morbidity indicators and questionnaire use for decisions that relates to control strategies.

Keywords

• school children
• Schistosoma haematobium
• Ghana
• questionnaire
• diagnosis
• haematuria