Comparative genomics: how has it advanced our knowledge of cryptosporidiosis epidemiology?

Whole genomic sequencing (WGS) and comparative genomics are increasingly used in the characterization of Cryptosporidium spp. They are facilitated by the establishment of procedures for WGS analysis of clinical specimens without laboratory propagation of pathogens. Results of recent comparative genomics analysis suggest that gene duplication might be associated with broad host ranges of some zoonotic Cryptosporidium species and subtypes, while genetic recombination could be involved in the emergence of virulent subtypes. The availability of WGS data has further facilitated the development of advanced molecular typing tools. The use of these tools together with comparative genomics analyses has begun to improve the investigations of outbreaks in industrialized nations. More WGS data, however, are needed from both industrialized nations and developing countries before we can have in-depth understanding of the population genetics and evolution of Cryptosporidium spp. and genetic determinants of various phenotypic traits in human-pathogenic subtypes.