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.