*4.3. DNA Extraction and PCR Amplification*

The E.Z.N.A.® Stool DNA kit (Omega Biotek Inc., Norcross, GA, USA) was used to extract the total DNA from 200 mg of each precipitated sample, according to the manufacturer's recommendations. PCR analysis of the small subunit (SSU) rRNA gene was employed to screen the infection of *Cryptosporidium* spp. in fecal samples in Bactrian camels [42]. Furthermore, PCR amplification and subsequent sequencing of the 60-kDa glycoprotein (*gp60*) gene were used to subtype *C. parvum*, *C. ubiquitum*, and *C. hominis* [32,43]. The PCR reactions for the SSU rRNA and *gp60* genes conducted in 25 μL reaction mixtures consisted of 12.5 μL of 2 × EasyTaq PCR SuperMix (TransGen Biotech, Beijing, China), 0.3 μM of each primer, 1 μL of DNA sample, and 10.9 μL double-distilled water. *C. parvum* was also determined using restriction fragment length polymorphism (RFLP) analysis, as previously described [44].
