Multiple Praziquantel Treatments ofSchistosoma mansoniEgg-Negative, CCA-PositiveSchoolchildren in a Very Low Endemic Setting in Egypt Do Not Consistently Alter CCA Results

22 April 2019
Ayat A. Haggag, Miriam Casacuberta Partal, Amal Rabiee, Khaled M. Abd Elaziz, Carl H. Campbell Jr., Daniel G. Colley and Reda M. R. Ramzy

Forty-fourSchistosoma mansoniegg-negative/circulating cathodic antigen(CCA)low-positive (trace or1+)children in three districts of very low prevalence in Egypt were given three sequential praziquantel (PZQ) treatments. Stooland urine specimens were collected 3 months following the initial treatment, and 3 weeks following the second andfollowing the third PZQ treatments, which were conducted 5 weeks apart. Stool specimens were examined by Kato–Katz(four slides/stool sample) and allS. mansoniegg-negative stools were further tested by the“miracidia hatching test”(MHT). Urine samples were examined by the point-of-care CCA assay (POC-CCA). Over the study period, all stoolsamples from study subjects remainedS. mansoniegg negative and MHT negative. Of the POC-CCA test results, in thefirst day of the study 3 months following the initial treatment, 29.5% were negative, 61.4% CCA trace positives, and 9.1%CCA 1+ positives. Following each PZQ treatment, the test resultsfluctuated between 1+, trace, and negative, but did notconsistently decrease. The proportions of POC-CCA–positive results obtained in thefirst day (70.5%) as compared withthe last day of the study (72.7%) in all of the three districts were very similar. We conclude that CCA trace and 1+ readings,in Kato–KatzS. mansoniegg-negative children in this area with very low levels of intestinal schistosomiasis, are notconsistently altered or rendered consistently negative following repeated PZQ treatments and are therefore likely torepresent false-positive readings. Thisfinding is of critical importance for countries such as Egypt as they approachelimination.

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