FIELD TRIAL OF 1-PERCENT NICLOSAMIDE AS A TOPICAL ANTIPENETRANT TO SCHISTOSOMA-MANSONI CERCARIAE

A randomized, double-blind, placebo-controlled field trial of a topica l anti-penetrant lotion, 1% niclosamide, applied daily to the upper an d lower limbs of farmers occupationally exposed to Schistosoma mansoni cercarial-infested water, was conducted in the Nile Delta to assess i ts safety and efficacy in preventing reinfection. Farmers aged 18-40 y ears were treated to cure their S. mansoni infections three months pri or to the onset of the trial. Subjects were randomly assigned to recei ve niclosamide or placebo lotion that was self-applied daily for five months. A total of 186 subjects met the inclusion criteria and complet ed the trial. The exposure to schistosomal-infested water occurred dur ing routine irrigation activities from June to November 199 1. Stool s pecimens were evaluated monthly during and for two months following th e lotion application period. The subjects applying the niclosamide lot ion were comparable to those applying placebo lotion in age (mean 30 y ears for both), total water contact (184.5 hr versus 173.8 hr), report ed lotion application compliance (88% versus 92%), and reported water contact involving skin exposure other than upper and lower limbs (23% versus 27%). The schistosomal reinfection rate was lower in the niclos amide group (53.3%) compared with the placebo lotion group (71.3%), (P < 0.02). Increased protection might be obtained with total body appli cation for shorter, less intense, water contact exposures.