Comparison of Kato-Katz, PCR and coproantigen for the diagnosis of Taenia solium taeniasis.

Four methods were compared for the diagnosis of human taeniasis caused by Taenia solium. Fecal samples from persons living in a T. solium endemic region of Madagascar were examined for taeniid eggs by the Kato–Katz method. Subsequently, samples positive ( n = 16) and negative ( n = 200) for T. solium eggs were examined by (i) amplification of the fragment of small subunit of the mitochondrial ribosomal RNA ( rrn S) gene using conventional polymerase chain reaction (PCR) and (ii) a nested PCR of a fragment of the T. solium Tso31 gene. Additionally, 12 egg-positive and all egg-negative samples were tested for coproantigen detection. A further 9 egg-positive fecal samples were examined using both PCRs. Of the 12 egg-positive samples tested by PCRs and coproantigen methods, 9 (75%) were positive by rrn S PCR, 3 (25%) using Tso31 -nested PCR and 9 (75%) by coproantigen testing. None of the 200 egg-negative fecal samples was positive in either rrn S or Tso31 -nested PCR. Twenty of the 25 egg-positive samples (80%) were positive in rrn S PCR, and DNA sequencing of PCR amplicons was obtained from 18 samples, all confirmed to be T. solium . Twelve of the 25 egg-positive samples (48%) were positive in the Tso31 -nested PCR, all of which were also positive by rrn S PCR. It is suggested that species-specific diagnosis of T. solium taeniasis may be achieved by either coprological examination to detect eggs or coproantigen testing, followed by rrn S PCR and DNA sequencing to confirm the tapeworm species in egg-positive or coproantigen-positive samples.