Detection of Parasite-Specific DNA in Urine Sediment Obtained by Filtration Differentiates between Single and Mixed Infections of Schistosoma mansoni and S. haematobium from Endemic Areas in Ghana

Abstract

Differential diagnosis of Schistosoma mansoni and S. haematobium, which often occur sympatrically in Africa, requires both urine and stool and the procedures are low in sensitivity. The standard diagnostic tests, such as Kato-Katz (KK) for S. mansoni eggs and presence of haematuria for S. haematobium both lack sensitivity, produce false-negative results and show reduced accuracy with decreasing intensity of infection. The need for a single diagnostic test with high sensitivity and specificity for both parasites is important as many African countries are implementing Mass Drug Administration (MDA) following recommendations of the World Health Organization (WHO). Eighty-six samples of urine sediment obtained by filtration were collected from a group of 5–23 years old people from an endemic area of southern Ghana. DNA was extracted from the urine sediment on filter paper from which a species-specific repeat fragment was amplified by polymerase chain reaction (PCR) with specific primers for S. mansoni and for S. haematobium. Additionally, all participants were tested by KK (stool) and dipstick for haematuria. Diagnostic parameters for all three tests were analyzed statistically. Amplification of species-specific DNA by PCR showed much higher sensitivity (99%–100%) and specificity (100%) compared to KK and haematuria (sensitivity: 76% and 30% respectively) for both schistosome species. The same pattern was observed when the data were stratified for age group and sex specific analysis. In addition PCR amplification detected DNA from 11 individuals infected with both parasites who were negative by KK and haematuria. This approach of detecting parasite specific DNA from either or both species in a single urine specimen is a practical advantage that avoids the need for two specimens and is more effective than standard tests including those based on serology. This promises to improve the effectiveness of surveillance of MDA control programs of schistosomiasis.

Diagnosis of Strongyloides stercoralis : Detection of parasite-derived DNA in urine

“…The low number of eggs or larvae released by females on a sporadic and unpredictable schedule compromises the sensitivity of these traditional diagnostic methods. Detection of specific cell-free DNA in urine appears to improve sensitivity over stool for some neglected tropical diseases (Ibironke et al 2012, Lodh et al 2014) as will be demonstrated here with Strongyloides .…”

Advances in the Diagnosis of Human Schistosomiasis

“…Sandoval et al (203) developed PCR assays based on ribosomal DNA (rDNA) that produced very sensitive and specific amplification of genus-and species-specific amplicons from five Schistosoma species (S. japonicum, S. mansoni, S. haematobium, S. intercalatum, and S. bovis); notably, they showed that urine could be used as the template for amplifying PCR products from both S. mansoni and S. haematobium. In a further advance, DNA isolation and specific PCR-based identification of S. mansoni and S. haematobium were achieved by use of urine sediments obtained by filtration (223). Indeed, PCR identification of S. mansoni in urine sediments has proved superior in diagnostic accuracy to the KK and urine CCA tests in areas of endemicity (224).…”

New diagnostic tools in schistosomiasis

“…This range largely reflects the quality and quantity of the microscopy procedures used in the different studies [96][97][98]. For the detection of DNA in urine, the sensitivity further increases by the use of concentration procedures such as sedimentation or filtration, the latter with potential application for population-based surveillance in more remote endemic regions [99,100].…”