Clonorchiasis in Taiwan

Abstract

Since Ohi in 1915 found clonorchiasis patients in Taiwan, many surveys have shown that Miao-li in the north, Sun-moon Lake in the middle and Mei-nung in the south of Taiwan are three important endemic areas of clonorchiasis. In recent studies, the disease showed a tendency to extend its endemicity. Rats, cats, dogs and pigs are the natural reservoir hosts, and 17 species of fresh water fish are also infected with metacercaria. One definitive snail host, Parafossarulus manchouricus, and two other suggested snails, Semisulcospira libertina and Thiara granifera, may serve as the first intermediate host. The human incidence is about 20-50% in endemic areas and 10-20% in newly infected localities. Higher infection rates and more intensities of the worm burden are observed in the adult males. A higher incidence is also observed in the Hakkanense ethnic group. The infection according to the occupation has changed from merchants and government employees to farmers. Praziquantel, 60 mg/kg body weight divided into three doses by oral route in one day, has been given to 356 patients and revealed a 96% cure rate and a 99% egg reduction rate. This regimen is highly recommended for the treatment of clonorchiasis.