Susceptibility of Argentinean Biomphalaria tenagophila and Biomphalaria straminea to infection by Schistosoma mansoni and the possibility of geographic expansion of mansoni schistosomiasis

IntroductionHuman migration and the presence of natural vectors (mollusks) of Schistosoma mansoni are the primary causes of the expansion of mansoni schistosomiasis into southern areas of South America. Water conditions are favorable for the expansion of this disease because of the extensive hydrographic network, which includes the basins of the Paraná and Uruguay rivers and favors mollusk reproduction. These rivers also aid agriculture and tourism in the area. Despite these favorable conditions, natural infection by S. mansoni has not yet been reported in Argentina, Uruguay, or Paraguay.MethodTwo species of planorbid from Argentina, Biomphalaria straminea and B. tenagophila, were exposed to the miracidia of five Brazilian strains of S. mansoni.Results Biomphalaria tenagophila (Atalaya, Buenos Aires province) was infected with the SJS strain (infection rate 3.3%), confirming the experimental susceptibility of this Argentinian species. Biomphalaria straminea (Rio Santa Lucía, Corrientes province) was susceptible to two Brazilian strains: SJS (infection rate 6.7%) and Sergipe (infection rate 6.7%). ConclusionThese results demonstrate that species from Argentina have the potential to be natural hosts of S. mansoni and that the appearance of foci of mansoni schistosomiasis in Argentina is possible.61161

[influence Of Hydrocortisone On Schistosoma Mansoni Development In Biomphalaria Glabrata].

The effect of hydrocortisone on the development of BH strain of S. mansoni in B. glabrata snails is evaluated. Snails in a randomly chosen group were submitted to hydrocortisone during four days. In the second day of hydrocortisone exposure, the snails were exposed, each, to ten S. mansoni miracidia. Another group, not treated with hydrocortisone, was exposed to miracidia and observed in the same manner. Various items of data were observed: the infection rate, survival time, prepatent period and total number of cercariae released. It was found that the snails in the group treated with hydrocortisone had a higher infection rate, shorter prepatent periods, produced more cercariae and also had longer survival times. This suggests that the hydrocortisone in snails induces a decrease in resistance to schistosome infection and facilitates the development of the trematode, while also reducing adverse infection effects, thereby leading to longer snail survival.35149-5

Susceptibility of Argentinean Biomphalaria tenagophila and Biomphalaria straminea to infection by Schistosoma mansoni and the possibility of geographic expansion of mansoni schistosomiasis

Introduction Human migration and the presence of natural vectors (mollusks) of Schistosoma mansoni are the primary causes of the expansion of mansoni schistosomiasis into southern areas of South America. Water conditions are favorable for the expansion of this disease because of the extensive hydrographic network, which includes the basins of the Paraná and Uruguay rivers and favors mollusk reproduction. These rivers also aid agriculture and tourism in the area. Despite these favorable conditions, natural infection by S. mansoni has not yet been reported in Argentina, Uruguay, or Paraguay. Methods Two species of planorbid from Argentina, Biomphalaria straminea and B. tenagophila, were exposed to the miracidia of five Brazilian strains of S. mansoni. Results Biomphalaria tenagophila (Atalaya, Buenos Aires province) was infected with the SJS strain (infection rate 3.3%), confirming the experimental susceptibility of this Argentinian species. Biomphalaria straminea (Rio Santa Lucía, Corrientes province) was susceptible to two Brazilian strains: SJS (infection rate 6.7%) and Sergipe (infection rate 6.7%). Conclusions These results demonstrate that species from Argentina have the potential to be natural hosts of S. mansoni and that the appearance of foci of mansoni schistosomiasis in Argentina is possible

Improvement of the oral praziquantel anthelmintic effect by cyclodextrin complexation

Schistosomiasis is a parasitic disease which kills a half million people per year, a I I over the world. Praziquantel (PZQ) is the drug-of-choice for schistosomiasis because of its effectiveness, ease of administration, and low cost. However, poor solubility restricts its delivery, especially via the oral route. In this study, we describe beta-cyclodextrin (beta-CD) complexation as an alternative to improve the PZQ bioavailability. Physicochemical analysis were performed to characterize the inclusion complex formed between PZQ and beta-CD. Differential scanning calorimetry (DSC) thermograms and morphological analysis using scanning electronic microscopy (SEM) gave evidences of the complex formation. Diffusion NMR experiments allowed determination of the fraction of PZQ bound to beta-CD (37%) and the association constant (941 +/- 47 M(-1)). The in vivo evaluation of the complexation on the effect of PZQ was performed on mice infected with Schistosoma mansoni (BH strain); after 15 days of treatment with the PZQ:beta-CD complex the efficacy, evaluated by the number of remaining alive worms, was 99%, against 59% elicited by plain PZQ.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq