Multiple Praziquantel Treatments of Schistosoma mansoni Egg-Negative, CCA-Positive School children in a Very Low Endemic Setting in Egypt Do Not Consistently Alter CCA Results
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.