Opisthorchis viverrini infection is an endemic disease that causes a serious public health problem in southeast Asia,
especially in northeast Thailand. We have developed a PCR method using a pair of primers named OV-6F}OV-6R for
detecting O. viverrini eggs in stool samples and compared it with Stoll's egg-count method. The primers were designed
based on the pOV-A6 speci®c DNA probe sequence which gave a 330 base pair product. The PCR method can detect a
single egg in arti®cially inoculated faeces or as little as 2¬10w"( ng of O. viverrini genomic DNA. The method gave 100%
sensitivity in all hamster groups except in animals exposed to the lowest intensity of infection (1 metacercaria}hamster).
In the ®rst month of infection, the PCR method was more sensitive than using the egg-count method in all infected groups
especially in the light infections. The PCR method was also successfully used in monitoring a therapeutic study. Since
the PCR method showed no cross-reaction with Heterophyid ¯ukes, it can be useful for speci®c identi®cation ofO. viverrini
eggs in stool samples without the risk of false positives. It also has great potential for application in clinical epidemiological
studies.