Frequency of soil contamination by Toxocara canis eggs in the south region of São Paulo municipality (SP, Brazil) in a 18 month period

Soil contamination by embryonic eggs of Toxocara canis is the main source of human infection by this ascarid larvae resulting, sometimes, in the occurrence of visceral larva migrans syndrome. The objective of the present research is to determine the frequency of T. canis eggs in soil samples monthly collected in nine public places, located at the South Region of São Paulo municipality in a 18-month period, from February 2004 to July 2005. The soil samples collected were treated with a 30% antiformine solution and with a sodium dichromate solution (d = 1.40) and microscopic slides were prepared and examined under light microscopy for searching T. canis eggs. Two peaks of higher frequency had been found, one in February - May 2004 and the other in April - July 2005.