Human clonorchiasis in new endemic areas of Taiwan, an epidemiological survey

Abstract

Intradermal testing with Clonorchis sinensis antigen was performed on students and inhabitants from Hsiou-Lin Hsiang, Hwalien County, the Pescador Islands, Tah-Wu Hsiang, Pintung County and Liu-Kwei Hsiang, Kaohsiung County. A lower positive rate was observed in each area except in Liu-Kwei Hsiang, where a rate of 6.0% was observed amongst inhabitants. Stool examinations were conducted on subjects from the areas described above and included subjects from the Kaohsiung Petroleum Factory, and a specia1 clinic of Chung-Ho Memorial Hospital, for parasitic diseases. Two children (0.25%) out of 714 primary school children from Liu-Kwei Hsiang, 59 subjects (2.8%) out of 2,141 workers and 70 (45.8%) out of 153 out-patients of the special clinic were confirmed to have C. sinensis infections. Upon the stool examination of inhabitants from 3 villages of Pintung County, 1) Tsu-Wei Village, Nei-Pu Hsiang, 2) Tou-Lun Village, Tsu-Tien Hsiang, and 3) Sin-Tien Village, Lin-Lo Hsiang, 72 case (10.6%) out of 677, 86 (10.2%) out of 843 and 176 (21.8%) out of 806 cases respectively were found to be infected by C. sinensis. According to the districts of residence and the intensity of infection expressed as eggs per gram feces, both the infection rate and infection intensity of subjects in Sin-Tien Village were significantly higher than the rates in the other two villages. In regard to sex, significantly more males were observed to have the parasite than the females among those 3 villages. This study revealed that the higher the age group of villagers, the more clonorchiasis cases and the greater the incidence of wormand. The infection peak of both males and females was found to be 45 to 54 years of age.