a multi-locus study of cryptosporidium parasites isolated from patients living in iran, malawi, nigeria, the united kingdom, and vietnam.

background: cryptosporidium species are important cause of diarrheal diseases in both developing and developed countries. this study aimed to compare the perfor-mance of several molecular methods for identification of cryptosporidium species, and to detect genetic variation among each of these species isolated from iran, ma-lawi, nigeria, vietnam and the united kingdom. methods: the oocysts dna samples were derived from 106 cryptosporidium posi-tive feces. polymerase chain reaction, pcr- restriction fragment length polymor-phism and dna sequence analysis of the 18s rrna and the cryptosporidium oo-cysts wall protein genes; pcr and dna sequence analysis of a fragment of 70 kda heat shock protein and 60 kda glycoprotein genes were carried out. results: based on these analysis, three species of cryptosporidium including c. homi-nis , c. parvum and c. meleagridis , and both c. hominis and c. parvum were found in iranian and the uk samples, respectively. also, three c. hominis (ib, ib3& id) and three c. parvum (iia, iic & iid) subtypes were identified by sequence analysis of the gp60 gene. of these, c. hominis ib was predominant and interestingly, one subgen-otype ( c. hominis ib a10g2) accounted for the majority of the samples. conclusion: the current study demonstrates the complex subtypes of cryptosporid-ium isolates in both developing and developed countries. this is the first report of c. parvum iid subgenotype and three new subtypes of c. parvum iia in the uk, a new subtype of c. hominis id from malawi; and the first multi-locus study of three species of cryptosporidium in human from iran.