1. Introduction
The Strongyloides genus includes 2 species of medical importance: S. stercoralis and S. fuelleborni. S. stercoralis has a cosmopolitan and heterogenous distribution, is endemic in the tropical and subtropical regions, and infects up to 100 million people ( Grove, 1996 and Olsen et al., 2009). Considering only active infections, strongyloidiasis is one of the major intestinal infections in humans; however, the number of people potentially exposed or with subclinical infection is much higher ( Elliott et al., 2007 and Siddiqui and Berk, 2001).