Circulating Schistosoma DNA in seropositive patients: A twostep diagnostic approach to rule-out acute and active chronic schistosomiasis in low transmission settings

Document Type : Original Article

Authors

1 Departments of Medical Parasitology, Faculty of Medicine, Al-Azhar Universities, Assiut

2 Departments of Medical Parasitology, Faculty of Medicine , Assiut

3 Departments of Medical Parasitology, Faculty of Medicine ,Cairo

4 Department of Clinical Microbiology, College of Medicine, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia

Abstract

Background: Since its discovery in 1850 by Theodor Bilharz at Kasr Al-Ainy hospital, Cairo, Egypt,
schistosomiasis continues to be a significant health challenge with a wide spectrum of chronic sequelae.
There is no reliable single gold standard conventional method (microscopy or serology) for communities
with low intensity and low transmission settings.
Objectives: To evaluate a two-step immunomolecular diagnostic approach to rule-out recent Schistosoma
re-infection in patients with characteristic pathological radiological features of chronic schistosomiasis.
Subjects and Methods: Single serum samples were collected from patients from Kafr El Sheikh, Egypt.
Selection of patients was based on microscopic absence of Schistosoma spp. eggs in either stool or urine
samples; abstinence from treatment by Praziquantel in the last 2 months; and clinical and radiological
diagnosis of pathological features of chronic schistosomiasis. All serum samples were serologically
examined using indirect hemagglutination test (IHAT) for identification of anti-Schistosoma antibodies.
Serum samples from 100 seropositive patients using IHAT were tested by multiplex PCR (mPCR) for
detection of species-specific cell-free circulating Schistosoma DNA.
Results: None of the seropositive serum samples were positive by PCR targeting Schistosoma speciesspecific
gene. Patients who were farmers and/or who had received Praziquantel treatment were associated
with Schistosoma seropositivity with statistical significance.
Conclusion: A two-step immunomolecular diagnostic approach, using a single serum sample, can rule-out
acute or active chronic schistosomiasis in patients that have characteristic pathological and radiological
features of chronic schistosomiasis. Also, the two-step approach avoids over-treatment and development
of drug resistance to Praziquantel, the only effective broad anti-Schistosoma medicine.

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