Parasite detection in sand from bays on the north coast of São Paulo state, Brazil

Soil contamination by protozoan parasites and soil-transmitted helminths (STH) is common in beach sand due to a number of factors such as pets, pluvial water, garbage, etc. These pathogens may cause many diseases in humans and animals and become a public health problem. Thus, systematic evaluation and inspection are necessary to develop control strategies regarding public contamination. For this purpose, our aims were to evaluate the parasitic profile of sandy soils on an urban beach and an untouched beach and correlate this with environmental and seasonal characteristics in Ubatuba, Brazil, in two seasons (winter and summer). 132 soil samples were collected for parasite analysis utilizing Rugai's method and the sedimentation adapted method. Our results showed positivity in 62% of the samples for at least one parasite in the urban beach and no parasitic structures on the untouched beach. The positivity was higher in summer (85%) than in winter (51.7%). All samples were positive for both, helminths and protozoa. Seasonal influence was noted regarding the presence of STH while for protozoa this influence was not observed. The parasitic structures most found were larvae of hookworms (35%) and Toxocara eggs (31.7%). We also noted the presence of Strongyloides sp, Ascaris lumbricoides, coccidia, Dipylidium caninum, Entamoeba hystolitica/dispar, Endolimax nana, Entamoeba coli, Giardia sp, Toxascaris leonina, Trichuris sp and Dibothricephalus latus. There was a positive correlation between temperature and the presence of STH in the sand samples. Most of the collection sites on the urban beach presented dogs or canine traces and garbage in both seasons. There was an association between the presence of dogs or their traces and parasitic structures. In conclusion, seasonality, urbanization and the presence of pets on beaches can potentially favor environmental contamination by parasites increasing the risk of transmission of zoonotic and parasitic diseases.

Toxoplasma gondii Infection Promotes Epithelial Barrier Dysfunction of Caco-2 Cells.

After oral infection, Toxoplasma gondii invades intestinal cells, induces breakdown of intestinal physiology and barrier functions, and causes intestinal pathology in some animal species. Although parasites' invasion into host cells is a known phenomenon, the effects of T. gondii infection in the intestinal barrier are still not well established. To evaluate morphological and physiological modifications on the colorectal adenocarcinoma-derived Caco-2 cell line during T. gondii infection, microvilli, tight junction integrity, and transepithelial electrical resistance (TEER) were investigated under infection. It was observed that the dextran uptake (endocytosis) and distribution were smaller in infected than in noninfected Caco-2 cells. The infection leads to the partial loss of microvilli at the cell surface. Claudin-1, zonula occludens-1 (ZO-1), and occludin expressions were colocalized by immunofluorescence and presented discontinuous net patterns in infected cells. Immunoblotting analysis at 24 hr postinfection revealed decreasing expression of occludin and ZO-1 proteins, whereas claudin-1 presented similar expression level compared with noninfected cells. T. gondii decreased TEER in Caco-2 cells 24 hr after infection. Our results suggest that T. gondii infection may lead to the loss of integrity of intestinal mucosa, resulting in impaired barrier function.