Plasmodium vivax: Impaired escape of Vk210 phenotype ookinetes from the midgut blood bolus of Anopheles pseudopunctipennis

The site in the midguts of Anopheles pseudopunctipennis where the development of Plasmodium vivax circumsporozoite protein Vk210 phenotype is blocked was investigated, and compared to its development in An. albimanus. Ookinete development was similar in time and numbers within the blood meal bolus of both mosquito species. But, compared to An. pseudopunctipennis, a higher proportion of An. albimanus were infected (P=0.0001) with higher ookinete (P=0.0001) and oocyst numbers (P=0.0001) on their internal and external midgut surfaces, respectively. Ookinetes were located in the peritrophic matrix (PM), but neither inside epithelial cells nor on the haemocoelic midgut surface by transmission electron microscopy in 24h p.i.-An. pseudopunctipennis mosquito samples. In contrast, no parasites were detected in the PM of An. albimanus at this time point. These results suggest that P. vivax Vk210 ookinetes cannot escape from and are destroyed within the midgut lumen of An. pseudopunctipennis.

Evaluation of the in vitro effect of albendazole, metronidazole and nitazoxanide on viability and structure of Giardia lamblia cysts

Effect of albendazole, metronidazole and nitazoxanide on the viability and structure of Giardia lamblia cysts isolates from infected children. The viability was evaluated by inducing excystation in a low-pH solution followed by an incubation in TYI-S culture medium. Nitazoxanide exhibited potent inhibitory effect (100%), metronidazole (79%) and albendazole (31%). The analysis among groups indicated a rs = 0.75 and p < 0.05. By TEM the cysts incubated with albendazole did not show morphological changes; with metronidazole, the formation of residual bodies in the nucleus border was observed. Incubated with nitazoxanide the damage to the cyst wall was evident, with the formation of areas with a granular content and the presence of cytoplasmic components in the peritrophic space. Our results propose that nitazoxanide showed a high effect on the viability and structure of G. lamblia cysts.