A comparison of a modified quick-Kato technique and the Stoll dilution method for field examination for Opisthorchis...

A modified quick-Kato technique and the Stoll dilution method for the diagnosis of Opisthorchis viverrini infection were compared from the standpoints of both replicability and sensitivity. One Stoll dilution preparation and two modified quick-Kato smears were prepared from single stool specimens collected from 221 persons in a village in north-eastern Thailand. Stool examinations were made in duplicate for each technique by two examiners, and the averages of the raw egg counts were used to estimate the intensity of infection. Statistical analyses revealed that the modified quick-Kato technique was slightly more sensitive, and thus would detect more positives, but was lacking in replicability and hence less suitable for measurement of individual intensity of infection. We therefore recommend the Stoll dilution technique for field surveys and measurement of individual intensity of O. viverrini infection.