Molecular Epidemiology, Spatiotemporal Analysis, and Ecology of Sporadic Human Cryptosporidiosis in Australia

Parasites from the Cryptosporidium genus are the most common cause of waterborne disease around the world. Successful management and prevention of this emerging disease requires knowledge of the diversity of species causing human disease and their zoonotic sources. This study employed a spatiotemporal approach to investigate sporadic human cryptosporidiosis in New South Wales, Australia, between January 2008 and December 2010. Analysis of 261 human fecal samples showed that sporadic human cryptosporidiosis is caused by four species; C. hominis, C. parvum, C. andersoni, and C. fayeri. Sequence analysis of the gp60 gene identified 5 subtype families and 31 subtypes. Cryptosporidium hominis IbA10G2 and C. parvum IIaA18G3R1 were the most frequent causes of human cryptosporidiosis in New South Wales, with 59% and 16% of infections, respectively, attributed to them. The results showed that infections were most prevalent in 0- to 4-year-olds. No gender bias or regional segregation was observed between the distribution of C. hominis and C. parvum infections. To determine the role of cattle in sporadic human infections in New South Wales, 205 cattle fecal samples were analyzed. Four Cryptosporidium species were identified, C. hominis, C. parvum, C. bovis, and C. ryanae. C. parvum subtype IIaA18G3R1 was the most common cause of cryptosporidiosis in cattle, with 47% of infections attributed to it. C. hominis subtype IbA10G2 was also identified in cattle isolates.