Several genetic regions such as the 18s rDNA, Cryptosporidium oocyst wall protein, heat shock protein 70, Acetyl-CoA gene, b-tubulin gene, Cp15 gene, Cp 11 gene, dihydrofolate reductase inhibitors (dhfr), microsatellite loci, and 60 kDa glycoprotein (gp60) have been commonly used to identify Cryptosporidium isolates in animal and human infections [33,39]. Here, DHFR is linked to infection.