Little effect of praziquantel or artemisinin on clonorchiasis in Northern Vietnam. A pilot study.

The first choice for treatment of Clonorchis sinensis infections is praziquantel. Experimental data suggest that artemisinin derivatives are active against C. sinensis. The efficacy of both drugs against clonorchiasis was evaluated in a pilot study in clonorchiasis patients in an endemic area in the North of Vietnam. Twenty-one patients received praziquantel 25 mg/kg o.d. for three days, the regular regimen in that area, and 21 patients were treated with artemisinin 500 mg b.i.d. for 5 days. Faecal egg counts were performed before as well as 6 days and 5 weeks after treatment. In the praziquantel group the faecal egg count decreased significantly from a mean value of 1632 eggs per gram faeces (epg) to 37 epg 5 weeks after treatment (P < 0.01) but, surprisingly, the eradication rate (95% confidence limit) at week 5 was only 29% (11-52%). In the artemisinin-treated group the reduction of the egg count was insignificant: from 1103 to 542 epg (P > 0.05). The proportion of patients (95% c.l.) with C. sinensis eggs in their stool on week 5 was 90% (70-99%) in the artemisinin group and 71% (48-89%) in the praziquantel group (P > 0.05) and the eradication rate (95% c.l.) at week 5 was only 10% (1-30%). With a sensitivity of detection of eggs in stool > 0.89, this implies a statistically significant but clinically unsatisfactory reduction for treatment with praziquantel. Sensitivity is probably less. For artemisinin there was no significant reduction. In conclusion, for human clonorchiasis in the North of Vietnam, the efficacy of praziquantel 25 mg/kg o.d. for 3 days was unsatisfactory and artemisinin for 5 days is not an effective alternative.