Assessing the marginal error in diagnosis and cure of Schistosoma mansoni in areas of low endemicity using Percoll and PCR techniques

OBJECTIVE: The Kato-Katz technique misses a proportion of low-intensity schistosomiasis cases. We set out to estimate the rate of false negative results after Kato-Katz. METHOD: Comparison with the more sensitive Percoll technique and polymerase chain reaction (PCR). RESULTS: Amongst Kato-Katz negative Schistosoma mansoni specimens in a hypoendemic area, Percoll detected 11% positive cases and PCR detected 23%. After treatment, the cure rate was 97% by Kato-Katz, 90% by Percoll and 71% by PCR. Results of Kato-Katz and Percoll showed moderate agreement, all cases positive by Kato-Katz were positive by Percoll. However, PCR showed some negative results amongst cases considered sure positives. CONCLUSION: The Percoll technique seems to be the technique of choice for diagnosis of S. mansoni in low intensity areas and after treatment.