Detection of schistosoma mansoni DNA in human blood as a diagnostic method for schistosomiasis

ABSTRACT

Schistosomiasis is a major health problem, the diagnosis of which relies on direct examination for ova, and/or serological assays for specific antibodies and circulating antigens. The present study aimed at evaluating the detection of Schistosoma mansoni DNA by polymerase chain reaction [PCR] versus the detection of antibodies by indirect haemagglutination test [IHAT] as means for diagnosis of Schistosomiasis in human blood. The individuals under study were categorized into four groups. Group I included 36 patients with active intestinal Schistosomiasis. Group II included 20 patients with past history of intestinal Schistosomiasis. Group III included 20 patients with Schistosoma haematobium and other parasitic infections, and finally group IV which included 15 individuals serving as negative controls. For all groups under study stool and urine were examined for parasitic ova; serum was examined for S. mansoni circulating DNA by PCR and for the detection of bilharzial antibody by IHAT. PCR proved highly significant in diagnosis of active intestinal Schistosomiasis with a sensitivity of 97.2%, specificity of 100%, predictive value of positive [PVP] of 100%, predictive value of negative [PVN] of 98.2% and a diagnostic accuracy of 98.9%. All cases in group II, III, and IV were negative. IHAT results showed a sensitivity of 77.8% in group I, 90.0% in group II, 25% in group III and in group IV all cases were negative. The specificity of IHAT in the diagnosis of active intestinal Schistosomiasis was 85.7%, with PVP 84.8% and PVN 78.9%; the diagnostic accuracy was 81.6%.S. mansoni DNA detection may be used as a valuable and species specific test for diagnosis of early infection or in situations of low worm burden in which other diagnostic methods show low sensitivity and specificity. Early treatment of such cases avoids the occurrence of irreversible pathological damage by the deposited eggs