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Pre- and post-treatment immunodiagnostic evaluation in human schistosomiasis mansoni
B A De Noya1, L Spencer, O Noya
1Instituto de Medicina Tropical, Universidad Central de Venezuela, Caracas.
Insights
The Circumoval Precipitin Test (COPT) is a sensitive tool for assessing schistosomiasis treatment effectiveness, especially in low-burden areas. COPT reactivity decreases after successful treatment, unlike ELISA-SEA, making it valuable for monitoring chemotherapy impact.
Area of Science:
- Tropical Medicine
- Immunology
- Parasitology
Background:
- Schistosomiasis control in low-burden, asymptomatic populations requires improved diagnostic tools beyond traditional methods.
- Current schistosomiasis control programs rely on coprologic techniques, which may be less effective in low-prevalence settings.
Purpose of the Study:
- To evaluate the utility of immunological methods, specifically the Circumoval Precipitin Test (COPT) and ELISA with soluble egg antigen (SEA), for seroepidemiologic studies and assessing chemotherapy impact in schistosomiasis control.
- To compare the sensitivity and post-treatment utility of COPT, intradermal test, and ELISA-SEA.
Main Methods:
- A cohort of 165 individuals infected with Schistosoma mansoni were followed for 12 months post-treatment.
- Circumoval Precipitin Test (COPT), intradermal test, and ELISA with soluble egg antigen (SEA) were performed before and at multiple time points after chemotherapy.
- Sensitivity analysis was conducted across different age groups and fecal egg excretion levels.
Main Results:
- COPT demonstrated high mean sensitivity (95.6%), particularly in a population with low fecal egg counts (88.4% < 100 eggs/gr).
- Children exhibited the highest reactivity to COPT.
- COPT reactivity significantly decreased in patients cured by treatment, becoming negative within a year, while it remained elevated in non-cured individuals.
- Intradermal test sensitivity was lower (58.2%), and ELISA-SEA showed no significant change one year post-treatment.
Conclusions:
- COPT is a valuable immunological tool for monitoring the impact of schistosomiasis chemotherapy, especially in low parasitic burden settings.
- Further research is needed to identify specific Schistosoma mansoni egg antigens that elicit antibodies disappearing after successful treatment, improving diagnostic specificity.
Abstract:
Schistosomiasis control seems to be different in countries were low parasitic burden and asymptomatic clinical patients are the features of majority of cases. Immunological methods must substitute the traditional coprologic techniques used for some decades in the Control Program. Circumoval Precipitin Test (COPT), intradermal test and ELISA with soluble egg antigen (SEA) are evaluated for using as tools for seroepidemiologic studies. COPT and ELISA were performed after treatment to known their utility when impact of chemotherapy must be assessed. One hundred sixty five persons were followed up 3, 6, 9 and 12 months after treatment. The mean sensitivity of COPT studied by age groups was 95.6% which is very important considering that 88.4% of the studied population excreted less than 100 eggs/gr of feces, while sensitivity of intradermal test was 58.2%. Children showed the highest reactivity to COPT. When treatment is effective, COPT reactivity progressively diminish until become negative one year later. In the non cure group, the COPT reactivity diminished but never below 20%. ELISA-SEA did not modify one year after treatment. Effort should be made to isolate fractions of eggs of Schistosoma mansoni whose antibodies disappear after treatment.