Soil contamination with parasites in public squares in the east zone of Sao Paulo, Brazil and the association with meteorological variables

Abstract

Several studies have demonstrated the contamination of public places with parasites with zoonotic potential and propagators of human infections. The soil-transmitted helminths are among the seventeen “Neglected Tropical Diseases”, according to World Health Organization, and affect more than one billion people in the poorest regions of the world. We studied the contamination by parasites in public squares in the eastern region of the city of São Paulo, Brazil, between September 2008 and October 2009, and evaluated whether there is a relationship between this contamination and the variables of precipitation and temperature. The samples, collected from ten public localities, were processed by the flotation technique in
saturated solution of sodium chloride. Of the 300 samples tested, 83.7% were
positive. An average from 11 to 2 eggs per gram dry weight was found. The parasites
more often found were of the genus Ascaris spp and Toxocara spp with proportions
of 44.5% and 34.2%, respectively. In addition, Nematode Larvae (16.2%), Hookworm (3.8%), Enterobius sp (0.6%), Hymenolepis spp (0.4%), Capillaria sp (0.2%) and Trichuris sp (0.1%) were also observed. Higher prevalence of fertile eggs, infertile eggs, cysts, and larvae of the parasite occurred in the rainy season which lasts from October to March, of these the most prevalent were fertile eggs. The precipitation and temperature variables were correlated with the total number of viable and / or nonviable eggs (p= 0.02 and 0.09).