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.