Large scale treatment of Clonorchis sinensis infections with praziquantel under field conditions.

A study on mass treatment of Clonorchis sinensis infections with praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a] isoquinolin-4-one, EMBAY 8440, Biltricide) was performed in order to find out the most effective and convenient administration scheme of this drug. 3543 (12.3%) out of 28 826 examined individuals were found to be infected with C. sinensis. First, the cellophane thick smear technique was used. Then the infected people were reexamined for determination of EPG (eggs per gram) using Stoll's egg counting technique. Of the infected cases, 2958 individuals were divided into 3 groups and treated with the following three administration schemes of praziquantel: 1. 40 mg/kg X 1 in one day; 2. 30 mg/kg X 2 (total 60 mg/kg) in one day; 3. 30 mg/kg X 3 (total 90 mg/kg) in one day; To evaluate drug efficacy, another stool examination was undertaken 2 months after treatment. Of the treated cases, 2,797 people could be evaluated by both cellophane thick smear and egg counting examinations. The results obtained were as follows: 1. When 40 mg/kg of praziquantel were administered once a day, the cure rate (egg negative conversion rate) was 87.1% and the egg reduction rate was 97.6%. 2. With the dose of 30 mg/kg twice a day with 5-h interval, the cure rate was 94.9% and egg reduction rate was 99.0%. 3. The dosage of 30 mg/kg three times a day with 5-h intervals resulted in 91.4% cure rate and 99.9% egg reduction. The treated cases were reexamined 5 h after drug intake.(ABSTRACT TRUNCATED AT 250 WORDS)