Cryptosporidium spp . in traction horses in Santa Maria , RS , Brazil

The protozoa Cryptosporidium spp. are nowadays considered as the primary agents of intestinal diseases in humans and animals (Johnson et al., 1997). They have a worldwide distribution and can be found infecting more than 170 different animal species (O'Donoghue, 1995). They belong to the phylum Apicomplexa, parasite the gastrointestinal microvilli epithelium and or the bronchial tree (Fayer et al., 2000). There are currently 14 species of Cryptosporidium well characterized (Xiao et al., 2004). In horses, the main specie is found to be C. parvum. The agent is an intracellular parasite, however, it is extra cytoplasmatic (Boch et al., 1982; Current, 1985; O ́Donogue, 1985) and when it infects the microvilli it is able to determinate their damage, affecting the absorption of nutrients and the performance of the animals.