the identification of human cryptosporidium species in tehran by pcr/rflp

objective :cryptosporidiosis is one of the most important parasitic infections in iran which causes diarrhea in humans and animals. the identification of the cryptosporidium species among humans is necessary. this study aims to identify species of cryptosporidium isolated from patients that referred to three hospitals in tehran based on the 18s rrna gene by nested pcr-rflp assay. ‎methods :in the first step of the present descriptive cross-sectional study, 1128 human fecal samples were collected from patients that referred to three hospitals (ali asgar, mofid and imam khomeini) in tehran. the samples were examined for ‎cryptosporidium by modified acid fast staining. in the second step, dna of the ‎positive samples were extracted, then gene of 18s rrna was amplified by ‎nested pcr in order to differentiate between species. the pcr products were subsequently digested by vsp1 restriction enzyme and their sequences determined. results: the modified acid fast method detected 12 (1.06%) positive samples which was confirmed by a molecular technique. the 845bp fragment of 18s rrna was digested ‎by restriction enzymes. there were 10 samples identified as cryptosporidium parvum that showed ‎similar patterns on 2.5% agarose gel; 2 other samples were identified as cryptosporidium homonis and cryptosporidium andersoni based on the different patterns and sequence results. conclusion: although cryptosporidium parvum is introduced as the major agent for ‎cryptosporidiosis in humans, cryptosporidium hominis and cryptosporidium andersoni may also infect humans.