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

Ayat A Haggag,Reda M R Ramzy,Daniel G Colley,Khaled M Abd Elaziz,Miriam Casacuberta Partal,Amal Rabiee,Carl H Campbell

doi:10.4269/ajtmh.18-0961

Abstract

.Forty-four Schistosoma mansoni egg-negative/circulating cathodic antigen (CCA) low-positive (trace or 1+) children in three districts of very low prevalence in Egypt were given three sequential praziquantel (PZQ) treatments. Stool and urine specimens were collected 3 months following the initial treatment, and 3 weeks following the second and following the third PZQ treatments, which were conducted 5 weeks apart. Stool specimens were examined by Kato–Katz (four slides/stool sample) and all S. mansoni egg-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 stool samples from study subjects remained S. mansoni egg negative and MHT negative. Of the POC-CCA test results, in the first 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 results fluctuated between 1+, trace, and negative, but did not consistently decrease. The proportions of POC-CCA–positive results obtained in the first day (70.5%) as compared with the 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–Katz S. mansoni egg-negative children in this area with very low levels of intestinal schistosomiasis, are not consistently altered or rendered consistently negative following repeated PZQ treatments and are therefore likely to represent false-positive readings. This finding is of critical importance for countries such as Egypt as they approach elimination.

Highlights

Schistosomiasis is a waterborne parasitic disease endemic in 78 tropical and subtropical countries worldwide
Several studies conducted in low prevalence areas have observed point-of-care CCA assay (POC-CCA)–positive persons who are S. mansoni egg negative by the Kato–Katz assay.[7,8,9]
Because this group (Kato–Katz–negative/POC-CCA–positive individuals) represents a challenge for programs shifting from control to elimination, we carried out an in-depth study of this particular group.[10]

Summary

Introduction

Schistosomiasis ( known as bilharzia) is a waterborne parasitic disease endemic in 78 tropical and subtropical countries worldwide. The disease is caused by an infection with blood flukes of Schistosoma spp. and is transmitted to humans through transcutaneous penetration by its larval stages following human direct contact with infested water.[1] By 2016, it was estimated that at least 206.4 million people required preventive treatment for schistosomiasis.[2] Successful schistosomiasis control programs in Japan, China, Brazil, and Egypt have shown that progression toward elimination of schistosomiasis through persistent control is feasible.[3] In some areas, the global emphasis is shifting from control to elimination of schistosomiasis.[4]. Successful schistosomiasis control programs, based on preventive chemotherapy using praziquantel (PZQ),[5] have significantly decreased disease endemicity. To overcome the drawbacks of the Kato–Katz stool examination in the diagnosis of Schistosoma mansoni infection, especially in low endemicity areas,[6] several programs have used a commercial point-of-care circulating cathodic antigen (POCCCA) test. We followed a cohort of 45 schoolchildren residing in a very low

Methods

Results

Conclusion