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Emetic tartar (ET), was used in the treatment of leishmaniasis but its use was discontinued due to its low therapeutic index. Liposomes have been shown to be a promising strategy for delivery of bioactive substances in the region of interest, in order to reduce and/or eliminate undesirable effects. In the present study, liposomes containing ET were prepared and characterized to evaluate acute toxicity as well as their leishmanicidal action using BALB/c mice with an inoculum of Leishmania (Leishmania) infantum. Liposomes were composed of egg phosphatidylcholine and 3ß-[N-(N′,N′-dimethylaminoethane)-carbamoyl]cholesterol, with an average diameter of 200 nm, zeta potential of +18 mV, and ET encapsulated into liposomes at a concentration near 2 g/L. Healthy mice were treated with ET or liposome containing ET (Lip-ET) in a single dose of 16 mg/kg of Sb3+ intravenously and observed for 14 days. The death of two animals in the ET-treated group and no deaths in the Lip-ET-treated group was observed. Higher hepatic and cardiac toxicity were observed in animals treated with ET when compared to animals treated with Lip-ET, blank liposomes (Blank-Lip) and PBS. The study of antileishmanial efficacy was conducted by intraperitoneal administration of Lip-ET, for ten consecutive days. It was observed by limiting dilution that treatments with liposomal formulations containing ET, as well as Glucantime®, led to a significant reduction in parasitic load in spleen and liver (p < 0.05) when compared to the untreated control group.

BACKGROUND: Schistosomiasis has a considerable impact on public health in many tropical and subtropical areas. In the new world, schistosomiasis is caused by the digenetic trematode Schistosoma mansoni. Chemotherapy is the main measure for controlling schistosomiasis, and the current drug of choice for treatment is praziquantel (PZQ). Although PZQ is efficient and safe, its repetitive large-scale use in endemic areas may lead to the selection of resistant strains. Isolates less susceptible to PZQ have been found in the field and selected for in the laboratory. The impact of selecting strains with a decreased susceptibility phenotype on disease dynamics and parasite population genetics is not fully understood. This study addresses the impact of PZQ pressure on the genetics of a laboratory population by analyzing frequency variations of polymorphic genetic markers. METHODOLOGY: Infected mice were treated with increasing PZQ doses until the highest dose of 3 × 300 mg/Kg was reached. The effect of PZQ treatment on the parasite population was assessed using five polymorphic microsatellite markers. Parasitological and genetic data were compared with those of the untreated control. After six parasite generations submitted to treatment, it was possible to obtain a S. mansoni population with decreased susceptibility to PZQ. In our experiments we also observed that female worms were more susceptible to PZQ than male worms. CONCLUSIONS: The selective pressure exerted by PZQ led to decreased genetic variability in S. mansoni and increased endogamy. The understanding of how S. mansoni populations respond to successive drug pressure has important implications on the appearance and maintenance of a PZQ resistance phenotype in endemic regions.

Los resultados de este trabajo muestran que el hamster (Cricetus auratus) puede ser utilizado como un modelo experimental para estudios inmunológicos en la infección por Schistosoma mansoni. Los datos obtenidos, relativos a inmunidad concomitante, producción de anticuerpo letal e inmunosupresión se asemejan a los conseguidos en otros modelos experimentales ya establecidos. Estas observaciones indican que el hámster, además de ser un hospedero satisfactorio para el mantenimiento del parásito en el laboratorio, puede ser considerado como un modelo experimental alterno cuyo crecimiento y mantenimiento son relativamente simples y además es un animal de fácil manejo.