Evaluation of microscopy, serology, circulating anodic antigen (CAA), and eosinophil counts for the follow-up of migrants with chronic schistosomiasis: a prospective cohort study

Gerardo B. Monteiro,Tamara Ursini,Pytsje T. Hoekstra,Paul L. Corstjens,Dora Buonfrate,Govert J. van Dam,Lisette van Lieshout,Francesca Tamarozzi,Federico Gobbi,Leonardo Motta,Ronaldo Silva,Cecilia Costa

doi:10.1186/s13071-021-04655-z

Abstract

BackgroundAn accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed. We assessed the performance of different laboratory parameters, including the up-converting reporter particle technology lateral flow assay to detect circulating anodic antigen (UCP-LF CAA), for the post-treatment follow-up of schistosomiasis in migrants attending a dedicated outpatient clinic in a non-endemic country.MethodsRoutine anti-Schistosoma serology results and eosinophil counts were obtained of patients with positive urine/stool microscopy and/or PCR (confirmed cases) or only positive serology (possible cases), and at least one follow-up visit at 6 (T6) or 12 (T12) months after praziquantel treatment. All sera samples were tested with the UCP-LF CAA assay.ResultsForty-eight patients were included, 23 confirmed and 25 possible cases. The percentage seropositivity and median antibody titers did not change significantly during follow-up. UCP-LF CAA was positive in 86.9% of confirmed and 20% of possible cases. The percentage positivity and median CAA levels decreased significantly post-treatment, with only two patients having positive CAA levels at T12.ConclusionsThe UCP-LF CAA assay proved useful for the diagnosis of active infection with Schistosoma spp. and highly valuable for post-treatment monitoring in migrants, encouraging the development of a commercial test.Graphical

Highlights

An accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed
The aim of this study was to assess the performance of different lab-based parameters, namely microscopy, serology, eosinophil counts, and Up-converting reporter particle technology-lateral flow (UCP-lateral flow (LF)) Circulating anodic antigen (CAA), for the post-treatment follow-up of schistosomiasis, either microscopy-confirmed or probable as defined by positive serology only, in migrants attending a dedicated outpatient clinic in a non-endemic area of Northern Italy
Schistosomiasis was confirmed by microscopy in 23 patients (47.9%), while 25 patients had possible infection (52.1%)

Summary

Introduction

An accurate test for the diagnosis and post-treatment follow-up of patients with schistosomiasis is needed. We assessed the performance of different laboratory parameters, including the up-converting reporter particle technology lateral flow assay to detect circulating anodic antigen (UCP-LF CAA), for the post-treatment follow-up of schistosomiasis in migrants attending a dedicated outpatient clinic in a non-endemic country. Schistosomiasis is a snail-borne disease caused by trematode flukes of the genus Schistosoma, affecting around 250 million people in at least 78 countries in tropical and subtropical regions, with over 90% of infections occurring in Africa [1]. Schistosomiasis occurs in tourists, expatriates, and migrants from endemic countries, representing a major health issue. A major obstacle in the diagnosis and monitoring of schistosomiasis is the lack of robust tests with high specificity and high sensitivity to assess the efficacy of treatment within a reasonable time frame

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