Infecção humana, aviária e a contaminação do solo pelo Toxocara spp em uma comunidade rural de Feira de Santana, BA

Abstract

Toxocariasis is a neglected geohelmintosis caused by Toxocara canis and T. cati, own of the dog and the cat, respectively. Paratenic hosts, including humans, may become infected by ingesting eggs with larvae in the soil, water, food and animals. Occult toxocariasis is the most common in man but may occur visceral larva migrans (liver and other organs), ocular larva migrans, and neurological changes. The objective of this research was to study the occurrence of Toxocara spp in humans from a rural community in Feira de Santana, Bahia, to evaluate the factors associated with human infection and environmental contamination, as well as verify the possibility of broilers raised extensively as indicators of ground contamination. A total of 425 human serum samples were collected and tested for serum anti-Toxocara spp antibodies by ELISAi, with 15.76% seropositive. Samples of 400g of soil from each of 15 properties were analyzed for trace element detection and determination of clay types, relating these data to the amount of parasite eggs per soil gram, the degree of plant cover, climatic and epidemiological (related to the presence of dogs and cats in properties) variables. The analysis of multivariate models of association of variables determined that the number of dogs was significantly associated with environmental contamination by Toxocara spp. Chickens from pathogen-free farms were used as indicators of environmental contamination, with 18 birds being released at 15 days of age on property with a history of dogs with Toxocara infection, having the blood collected at 0, 15 and 30 days after the release. Serum anti-Toxocara spp antibodies examination by ELISAi resulted in increasing reactivity indices. Soil samples revealed a higher frequency of embrionated than infertile Toxocara eggs. At the end of the experiment, the intestinal contents were obtained for coprological examination of nine of these birds. Eggs of Ascaridia galli were found in all nine birds examined and in five of these were recovered adults of A. galli. It is demonstrated the infection of people, the epidemiological characteristics capable of maintaining Toxocara eggs and the potential of birds created extensively as markers of environmental contamination.