Comparison of a Polymerase Chain Reaction and the Kato-Katz Technique for Diagnosing Infection With Schistosoma Mansoni

Abstract

Fecal samples from 194 individuals living in an area of Brazil endemic for Schistosoma mansoni were analyzed by a polymerase chain reaction (PCR) and the Kato-Katz parasitologic examination. Statistical analysis of the results showed a kappa index of 0.8 between the two methods. The prevalence of infection was 30.9% in three fecal samples examined by the Kato-Katz method, but 38.1% in one fecal sample examined by the PCR technique. Repeated survey of discordant results showed that five (41.6%) of 12 parasitologically negative cases for which PCR gave positive results were misdiagnosed by Kato-Katz examinations. The PCR technique showed a sensitivity of 96.7% and a specificity of 88% when the parasitologic examination was used as the reference test. The efficacy of cure with praziquantel was 87.8% in three parasitologic stool examinations and 75.6% in one PCR survey. These results demonstrate that the PCR assay might be a valuable alternative for diagnosing Schistosoma infections.

Faecal examination and PCR to detect Strongyloides venezuelensis in experimentally infected Lewis rats

“…In this case, sensitivity was 60% and 0% for EPG and PCR with the species primer, respectively. Even though a direct comparison with the literature is not possible due to differences in the experimental model and design, the described findings are similar to already published data in this field (Wongratanacheewin et al 2001, Pontes et al 2003, Sandoval et al 2006.…”

“…Pontes et al (2003), for example, demonstrated that PCR was much more sensitive than the KatoKatz technique (Katz et al 1972) to detect Schistosoma mansoni in human faeces. Similar results were observed in S. mansoni infected mice (Sandoval et al 2006).…”

Further evaluation of an updated PCR assay for the detection of Schistosoma mansoni DNA in human stool samples

“…Pontes et al (2002) reported the first use of PCR for the diagnosis of Schistosoma mansoni DNA in faecal samples. High sensitivity and specificity rates were observed by this (Pontes et al 2003) and another group (Allam et al 2009) when compared to routine parasitological examination according to the Kato-Katz method (Katz et al 1972).…”

Polymerase chain reaction for the evaluation of Schistosoma mansoni infection in two low endemicity areas of Minas Gerais, Brazil

“…Considered the gold standard method by the World Health Organization (WHO 1993), the Kato-Katz technique has superior sensitivity in comparison to other parasitological techniques for S. mansoni eggs (Chaves et al 1979, Santos et al 2005, Enk et al 2008. However, this technique becomes less efficient when the specimens contain a small amount of eggs, as in post-treatment situations and low endemicity areas (De Vlas & Gryseels 1992, Engels et al 1997, Kongs et al 2001, Pontes et al 2003, Enk et al 2008.…”

“…However, polymerase chain reaction (PCR) has recently been employed in the diagnosis of S. mansoni and has demonstrated high specificity and sensitivity in the detection of DNA in stool samples from patients in endemic areas (Pontes et al 2003, Allan et al 2009, Gomes et al 2009). This method of diagnosis has been shown to be 10-fold more sensitive than the Kato-Katz technique .…”