SCHISTOSOMA-MANSONI - MATURATION RATE AND DRUG SUSCEPTIBILITY OF DIFFERENT GEOGRAPHIC ISOLATES

The fecundities and drug susceptibilities of Schistosoma mansoni isola tes from Senegal, puerto Rico, and Kenya have been examined in mice. T he Senegal parasite, obtained from the field in 1993, was shown to hav e a longer prepatent period (eggs first recovered in the faeces on Day 46 after infection) than those of two isolates, from Puerto Rico and Kenya, that had been maintained for a long period in the laboratory (f aecal eggs recovered on Days 38 and 36 after infection, respectively). A Kenyan isolate, also collected from the field in 1994, was shown to mature more slowly than the laboratory-maintained Kenyan isolate. Tis sue egg counts confirmed that early in infection the fecundity of the recently collected isolates from Senegal and Kenya was significantly l ower than that of the long-term laboratory-maintained Kenyan isolate. Praziquantel and oxamniquine treatment of 8-week-old infections caused a significant (P < 0.001) reduction in worm burden in all isolates te sted. However, the reduction in worm burden after praziquantel treatme nt of infections of the Senegal isolate (50% reduction) was significan tly lower than the >90% reductions in worm burdens after praziquantel treatment of mice infected with either of the Kenyan isolates (P < 0.0 01). The study confirms that despite being tolerant to praziquantel, t he Senegal isolate is fully susceptible to oxamniquine. The praziquant el tolerance of the Senegal parasite is not solely attributed to the s tate of maturation of the parasite at the time of drug administration. (C) 1997 Academic Press.