Thecox1 gene was used as a conserved target for the S. stercoralis-specific nested PCR. Nested PCR not only iden-tified all parasitologically positive samples (85/466 samples)as positive, but also 32 additional samples that could not be
detected by parasitological methods. Considering parasito-logical methods as the gold standard, diagnostic sensitivity
and specificity of nested PCR were 100% and 91.6%, respec-tively. However, the selected nested PCR products, including
four parasitologically negative samples, were confirmed as
S. stercoralisby sequence analysis. Therefore, deeming these
32 parasitologically negative but nested PCR-positive samples
as true positive, the specificity of nested PCR assay is increased.
In fact, nested PCR was the only method that did not miss
any cases found positive by either of other three methods