Phenotypic and genotypic characterization of Cryptosporidium species and isolates

Recent outbreaks of cryptosporidiosis from contaminated water supplies have led to a need for the detection of Cryptosporidium oocysts from various hosts and contaminating sources. The presence of nonpathogenic species or strains of Cryptosporidium is important for diagnostic purposes as there is a potential for false-positive detection of pathogenic parasites. The present review focuses on phenotypic differences and recent advances in genotypic analyses of the genus Cryptosporidium with an emphasis on detecting various isolates and identifying differences in Cryptosporidium parvum and other species in this genus. The information currently available demonstrates important patterns in DNA sequences of Cryptosporidium, and our understanding of macro- and microevolutionary patterns has increased in recent years. However, current knowledge of Cryptosporidium genetic diversity is far from complete, and the large amount of both phenotypic and genotypic data has led to problems in our understanding of the systematics of this genus.