Indexed on: 01 Jan '77Published on: 01 Jan '77Published in: Zeitschrift fur Parasitenkunde (Berlin, Germany)
Groups of six- to eight-week-old hamsters each experimentally infected with Sudanese and South African strains of S. haematobium, Puerto Rican and Liberian strains of S. mansoni, S. japonicum from mainland China, a Congo strain of S. intercalatum and a Nelspruit South African strain of S. mattheei, were treated with different dosage regimens of a new schistosomicide — praziquantel.The drug is more effective against S. haematobium when administered by the intramuscular route than per os, a complete parasitological cure being obtained following a single intramuscular injection of 200 mg/kg bwt. Per os the best results were obtained using the three highest regimens of 5×100 mg/kg, 5×50 mg/kg and 3×100 mg/kg bwt. It was observed that S. haematobium female worms are more susceptible to the compound than male worms.The results show that S. japonicum in the hamster is very susceptible to the compound, a dosage of 100 mg/kg administered orally for three days resulting in a complete parasitological cure. More than a 90% reduction in adult worms was obtained at all the dosage regimens used except 1×50 mg/kg (73.2%). Female worms were again found to be more susceptible to the drug than male worms. Hatching tests performed on ova in liver tissue of control and treated animals were positive up to four weeks after treatment, thus showing that praziquantel has no ovicidal properties.Immature S. japonicum worms were found to be markedly less susceptible to treatment than the mature schistosomes (5×100 mg/kg reduced mature adults by 99.7%, but immature forms were reduced by only 54.2%).A 100% cure rate was obtained in the hamster infected with the Liberian strain of S. mansoni following treatment with praziquantel at 3×100 mg/kg given on consecutive days, and at 3×50 mg/kg administered in one day. Treatment of the hamsters infected with the Puerto Rican strain of S. mansoni also resulted in substantial reductions of adult worms. Praziquantel was also found to be highly effective against S. intercalatum and S. mattheei.It is noted that the efficacy of the compound against S. haematobium, S. japonicum and S. mattheei in the hamster is significantly greater than that of metrifonate (Bilarcil). Following treatment with praziquantel most S. haematobium and S. japonicum worms undergo a classic hepatic shift and are trapped and killed in the liver tissue.It is considered that the present study shows that this new compound exhibits a high degree of activity against the three major schistosome species S. haematobium, S. japonicum and S. mansoni, against S. intercalatum, and against the cattle schistosome S. mattheei in the hamster, with no apparent significant differences in efficacy against the different geographical strains of the parasites used in the trials.