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

Abstract

Background 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. Methods Routine 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. Results Forty-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. Conclusions The 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.

Evaluation of antibody serology to determine current helminth andPlasmodium falciparuminfections in a co-endemic area in Southern Mozambique

“…Serological tests based on the detection of antibodies to whole S. stercoralis parasites or crude extracts have already shown excellent results (39, 40). Nonetheless, the need for a constant supply of parasites and variability of the source are limitations of those assays (41). On the other hand, antibody serological methods based on recombinant proteins, such as NIE (42), are more reproducible.…”

Context-Specific Procedures for the Diagnosis of Human Schistosomiasis – A Mini Review

“…Antigen-levels are generally associated with the number of worms present (27). Other unique characteristics of these antigens include the clearance from the blood circulation into the urine with little day-to-day variation (28,29), and the decrease in levels within days or weeks after PZQ treatment (30)(31)(32)(33)(34)(35)(36)(37), making antigen detection highly suitable for individual treatment monitoring.…”

“…CAA can be detected in urine and serum via the Up-Converting reporter Particle technology based, Lateral Flow (UCP-LF) CAA test (44). The UCP-LF CAA test has been evaluated in various endemic and non-endemic settings and has demonstrated high specificity and sensitivity for the detection of all human species including hybrids (31,34,35,37,(44)(45)(46)(47)(48)(49)(50)(51)(52). Different formats of the UCP-LF CAA test have been developed, including a dry format which allows storage and worldwide shipment of reagents without a cold chain as well as a format applying larger sample volumes thereby increasing sensitivity (44).…”

“…Detecting Schistosoma-specific antibodies remains the recommended and most used first-line test for screening migrants (97,98), However, as these methods have their limitations both in sensitivity and specificity in this specific group of suspected infections, the detection of eggs in urine or stool is commonly used to confirm infection, even though its sensitivity is limited (5). A better alternative is the detection of Schistosoma DNA or circulating antigens in clinical samples, as both have demonstrated to be of clinical value when monitoring schistosomiasis in migrants after their arrival in Europe (37). The POC-CCA test can be a useful screening tool for S.mansoni infections when used in a standardized manner (99)(100)(101).…”

“…The POC-CCA test can be a useful screening tool for S.mansoni infections when used in a standardized manner (99)(100)(101). However, detection of CAA as a routine procedure seems most efficient for migrants originating from different regions, as CAA is found in all Schistosoma species including hybrids and is also most suitable to diagnose low intensity infections (37).…”