Abstract: 　Objective To analyse the genetic heterogeneity of 8 isolates of Cryptosporidium belonging to three species ( Cryptosporiduim muris,Cryptosporiduim parvum and Cryptosporidium meleagridis ) using RAPD technique.Methods DNA extracts of the 8 isolates were amplified by PCR using 26 out of 200 primers. The amplified products were separated by agar electrophoresis followed by staining with ethidium bromide.Results RAPD analysis revealed:① Obvious differences among species were found, the average genetic distance being 7.037;② Certain differences among different isolates of the same species were found,the average genetic distance being 5.162.Conclusion RAPD could differentiate the common and respective gene fragments of the 8 isolates of Cryptosporidium .

Key words: Cryptosporidium, RAPD, genetic distance