EFFICACY AND SIDE-EFFECTS OF PRAZIQUANTEL IN AN EPIDEMIC FOCUS OF SCHISTOSOMA-MANSONI

Schistosoma mansoni was first reported in the area of Richard Toll (Se negal) in 1988 and spread rapidly in the community, after a series of human-engineered ecologic changes. A random population sample (n = 422 ) from Ndombo, a village near Richard-Toll, was studied in 1991 by sto ol examination (four Kato slides from two stool samples) and antigen d etection in urine and blood. Stool-positive individuals were treated w ith 40 mg/kg of praziquantel. A house-to-house interview regarding sid e effects was conducted 24 hr after treatment. Two hundred ninety-eigh t subjects were re-examined IO days (antigen detection) and 12 weeks ( egg counts, antigen detection) after treatment. Before treatment, posi tive egg counts were found in 98% of the subjects, with 41% excreting more than 1,000 eggs per gram (epg) of feces. Treatment of 352 individ uals caused serious but transient side effects (colic, vomiting, urtic aria, and edema), the frequency of which increased with increasing egg counts. The parasitologic cure rate 12 weeks after treatment was only 18%, the frequency of egg counts with more than 1,000 epg decreased t o 5%, and the mean egg count of those remaining positive was reduced b y 86%. Antigen detection in serum 10 days and 12 weeks after treatment remained positive in 90% of the subjects; although titers decreased s harply. The low cure rates may be due to intense transmission and/or u ndeveloped immune responses in this recently exposed population. Howev er, reduced drug susceptibility of the parasite strain has now been co nfirmed in one local isolate.