Abstract
(English)
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Evolution of pathological lesions of the urogenital system due to Schistosoma haematobium, assessed by ultrasound, over a period of three months after standard treatment with praziquantel among school children in southeastern Tanzania
176 schoolchildren infected with Schistosoma haematobium (positive egg counts or microhematuria) were non-randomly selected in two schools in an area of moderate intensity in Tanzania.. They were treated with praziquantel at a dosage of 40 mg/kg body weight at either baseline only or twice at baseline and one month later. Children were examined at 4 and 12 weeks after treatment. A subcohort of 79 children were investigated in a more detailed way at 2, 4, 6 and 12 weeks after treatment.
690 children were screened for infection. The prevalence of S. haematobium infection was 64.9 %. S. haematobium eggs were detected among 76.3% of 409 children in at least one of five urine samples. The intensitiy was high: 40.1% showed ³ 50 eggs/10 ml of urine, 23.7% ³ 100 eggs/10 ml of urine. This was reflected in the fact that 74.8% had microhaematuria (63% with grade ³3).
Pathologic lesions of the urinary tract were detected by ultrasound in 66% of the children, 9% of them were severe. Lesions of the bladder wall were significantly associated with egg output (c21 = 48.87, P < 0.0001) and with microhaematuria (c21 = 45.34, P < 0.0001). Overall pathology was significantly associated with age, which was categorized into older (³ 12 years) and younger (< 12 years) groups. Older children were more than two times as likely as younger children to be affected (OR=2.5, 95% CI= 1.62, 3.86).
A total of 79 children were examined for infection and pathology in a more detailed way at 2, 4, 6 and 12 weeks after treatment.
In the cohort, 99% of the children had major pathology (20% severe). Nearly all children presented bladder lesions of which 97% were major lesions. Pathologic lesions of the upper urinary tract were found in 14% of all cases. No significant difference was found between the cohort and the subcohort.
The detailed analysis of the different pathology stages at baseline showed that nearly all of the 79 children had major pathology (60 moderate, 18 severe). Only one case had minor pathology. Among the 18 children with severe pathology, 3 (17%) were free of morbidity after three months, the other ones regressed into minor pathology (8/18) or remained with major pathology (7/18, 6 moderate and 1 severe). Among the 60 pupils with moderate pathology, almost half of them cleared pathology (29/60), 18 (30%) cases regressed from major into minor pathology and 13 (22%) didn't show any improvement. At the end of the three months, 33 of the 79 children (42%) didn't show lesions any more. Among the 46 others (58%), 26 (33%) remained with mild pathology and 20 (25%) with major pathology (19 moderate, 1 severe).
Preliminary analysis of the data showed no significant differences in the evolution of pathological lesions between the two treatment groups, indicating the adaequate cure rate with single dose treatment in this transmission area.
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