Epidemiology of Schistosomiasis and Usefulness of Indirect Diagnostic Tests in School-Age Children in Cubal, Central Angola

Abstract

IntroductionSchistosomiasis remains a public health major problem and little is known in many areas, mainly in Sub-Saharan AfricaObjectivesTo assess the burden and risk factors of schistosomiasis and intestinal parasitic helminthes in the children of Cubal, Angola, and to compare different diagnostic approaches for urinary schistosomiasis under field conditions.MethodsA cross-sectional study was conducted. Urine and faeces samples of school children were microscopically studied. A random sample of children was obtained from an alphabetically arranged list of children, taking one of two children. Urine dipstick, colorimetric test and macrohaematuria were considered as indirect diagnostic methods and compared to direct urine examination. Possible risk factors for the infection were sex, age, distance to the river and previous treatment with praziquantel; the assessment was performed using Chi-square test.ResultsA total of 785 (61.18%) children showed S. haematobium eggs in urine; children living within 500 meters from the river had a higher odds for infection: Odds ratio 1.97 (1.45–2.7 CI 95%); urine dipstick showed sensitivity of 96% and specificity of 61.3%, with a positive predictive value; colorimetric test showed sensitivity of 52.5%, specificity of 74.6% and a positive predictive value of 77%. Proteinuria was present in 653 (51.1%) children, being more frequent in children with S. haematobium in urine (75.2%); 32 of 191 stool samples (16%) showed the presence of other intestinal parasites and 8 (4%) for S. haematobium.ConclusionsPrevalence of urinary schistosomiasis in our study area is much higher than the national average, considering it as a high-risk community. Proximity to a source of water was a risk factor for the infection. Indirect tests, as urine dipstick and colorimetric test, were useful tools for diagnosis, due to ease of use and low cost. Proteinuria was a common finding, probably showing an early structural damage due to schistosomiasis in this group of children.

Field and laboratory comparative evaluation of a LAMP assay for the diagnosis of urogenital schistosomiasis in Cubal, Central Angola

“…In this work, the prevalence of S. haematobium infection was 50.6% and 48.3% as diagnosed using direct microscopy and urine strip tests, respectively. These values resulted slightly lower than those reported in a recent study in Cubal (61% and 52%, respectively), and no statistically significant association was found in relation to age or sex, thus supporting the idea of a high transmission for S. haematobium in Cubal and surroundings [42]. However, in this study, when we tested the urine samples by LAMP assay using purified DNA, the overall prevalence increased significantly reaching 73.8%.…”

Ultrasound findings and associated factors to morbidity in Schistosoma haematobium infection in a highly endemic setting

“…These results are consistent with findings in other studies [21,23], but occurred a higher proportion in our setting. Boys had a higher risk of having any lesion in the urinary tract; this difference has been previously shown and is usually attributed to a higher parasite burden due to swimming or working on irrigated agricultural farm lands [16,24,25]. Regarding the alterations of the upper urinary tract, no difference by sex was observed.…”

“…Both types of schistosomiasis (urinary and intestinal) are endemic in Angola [14,15]. In the Cubal district in central Angola, a recent survey reported a prevalence of urinary schistosomiasis of 61% for school-aged children; no intestinal schistosomiasis was detected [16]. We aimed to assess the use of ultrasound to detect internal damage of the urinary tract in this same group of children, and whether urine dipstick tests could be useful to predict internal damage in a highly endemic context.…”

Ultrasound Evolution of Pediatric Urinary Schistosomiasis after Treatment with Praziquantel in a Highly Endemic Area

“…We analyzed 1,283 urine samples, of which 785 (61%) were positive for the presence of S. haematobium eggs. 16 Subsequently, 11 of these schools were randomly selected; all patients diagnosed with schistosomiasis in these 11 schools (627 children) were cited for urinary ultrasound; of them, 127 (25%) attended. Treatment with praziquantel was administered at a dose of 40 mg/kg on the same day.…”

“…A recent parasitological survey in the Cubal district in Central Angola showed a prevalence of urinary schistosomiasis of at least 61% in school-age children. 16 Thus, this area is considered a highly endemic area where no MDA or other preventive activities have yet been undertaken.…”