ELECTRON-MICROSCOPIC OBSERVATIONS OF TEGUMENTAL DAMAGE IN ADULT SCHISTOSOMA-JAPONICUM AFTER IN-VIVO TREATMENT WITH LEVO PRAZIQUANTEL

The in vivo effects of a single dose of levo-praziquantel, 75 mg/kg in PEG 400, on the tegumental surface of adult S. japonicum were compare d with the effects of a single dose (150 mg/kg) of the mixed isomer pr eparation, using scanning and transmission electron microscope. Worms were recovered from mice at 10 min, 30 min, 1 hr, 4 hr, 12 hr, 24 hr a nd 48 hr after treatment. After 10 min exposure to either compound, th e tegumental folds and sensory organelles were swollen and the tegumen t vacuolated. After 12-24 hr, the surface was eroded and exfoliated wi th exposure of intrategumental and/or subtegumental tissues and attach ment of leukocytes to the denuded areas. Vehicle controls were normal throughout the time period examined. These studies demonstrate that th e levo isomer of praziquantel causes acute structural damage to the te gument similar to that seen with the mixed isomer preparation.