ABSTRACT
Environmental contamination by Toxocara spp eggs can be verified by parasitological techniques, which are mostly laborious, have low sensitivity, and may require repeated tests to establish the contamination status of a certain area. Given the significance of this parasite as an agent of infections in humans, that may cause blindness, especially in children, broilers chickens created extensively were evaluated as possible markers of parasite environmental contamination, through the detection of anti-Toxocara serum antibodies. Eighteen 15-day-old Label Rouge broilers were released on a farm with a history of dogs with Toxocara infection. At 0, 15 and 30 days after the release birds blood samples were taken, as well as soil samples. At the end of the experiment the birds were slaughtered, and the gastrointestinal tract was collected for coprological exams. The presence of anti-Toxocara antibodies resulted in increased reactivity indexes with time, and at 15 days five of the birds were positive and at 30 days, seven birds showed seroconversion. Examination of the soil samples by the centrifugation-flotation method in hyper saturated zinc sulfate solution revealed contamination by embryonated or infertile eggs of Toxocara at all times of collection, as well as the presence of Ascaridia eggs at 15 days after release of birds. Examination of bird's stool samples at the end of the experiment demonstrated 100% infection by Ascaridia galli, however there was no correlation between the counts of this parasite and the ELISA reactivity indices for anti-Toxocara antibodies. The results obtained allow us to infer the possibility of using anti-Toxocara spp-specific antibodies determination in birds raised extensively, which could then serve as sentinels of environmental contamination by this parasite.
ABSTRACT
Since 1950, the human infection by parasites of the genus Toxocara, characterized by migration and permanence of larvae of the parasite in the liver, lungs, eyes, and brain, have been reported. The route of infection is the ingestion of embryonated eggs present in soil and contaminated vegetables, however there are reports of human illness associated with ingestion of viscera of paratenic hosts, including birds. This work aimed to detect the presence of larvae in the tissues and antibodies in the serum of poultry sold in street markets of Feira de Santana, Bahia, Brazil. Over a period of ten months, 100 birds of four street markets in the city were acquired, being examined organs and muscle tissue for the presence of larvae and the serum for the presence of anti-Toxocara spp. antibodies by indirect enzyme-linked immunosorbent assay (ELISA). Helminth larvae were not found in the examination of pepsin digested tissues, but 80 (89.9%) of 89 bird sera examined presented anti-Toxocara spp. IgY antibodies. These results may indicate that birds are coming from contaminated environments, where man and other animals can also be infected.
