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Schistosomiasis, intestinal
Diagnostic Methods
Diagnostic methodsPros and cons
Parasitological diagnosis 
Detection of ova in stool samples has limited sensitivity even in heavy infections since egg excretion varies considerably between days. Several samples (3–5) have to be analysed to achieve a high predictive value for a negative result.
  • Insufficient sensitivity of parasitological methods even when concentration methods are used
Molecular diagnosis 
First attempts have been described to detect parasite DNA in stool samples by PCR. This method is not yet fully validated.
As a research tool, molecular techniques, such as restriction fragment length polymorphism (RFLP) analysis, polymerase chain reaction (PCR) and DNA sequencing are now proving invaluable tools for distinguishing species and strains of schistosomes.
 
Antigen detection 
First attempts to detect circulating proteoglycans in blood or urine of infected patients by various immunological methods started over 30 years ago. Today, a reagent strip test for the detection of the circulating cathodic antigen (CCA) in the urine is close to an end-user format.
  • Not yet fully validated
  • So far conflicting results on sensitivity (80–100%)
  • Less sensitive in light infections (travellers)
  • Moderate specificity (80–90%)
  • Urine samples easier to obtain than blood samples
Antibody detection 
There are many home-made serological assays developed by different laboratories. The most frequently used test formats are the indirect fluorescent antibody test (IFA) using frozen sections of adult worms, and immunoenzyme assays (mostly ELISAs) with crude or recombinant antigens from eggs or adult worms.
  • Excellent as screening test after potential exposure (travellers in the tropics etc.) since microscopy has a low sensitivity
  • False-positive results due to other tissue helminths
  • No correlation with worm burden
  • Long persistence of antibodies after cure