Molecular epidemiology of cryptosporidiosis outbreaks and transmission in British Columbia, Canada

Isolates from 25 (13 sporadic and 12 outbreak) cryptosporidiosis cases, 24 of which were from British Columbia, Canada, were characterized using neste d polymerase chain reaction amplification of the polymorphic internal trans cribed spacer I locus. Two predominant Cryptosporidium parvum genotypes wer e found. Twelve (8 sporadic and 4 outbreak) isolates amplified with the cry 7/cry21 primer pair and 12 (5 sporadic and 7 outbreak) isolates amplified w ith the cry7/cryITS1 primer pair. Multi-locus gene analysis using sequence polymorphisms on 3 other loci, i.e., the thrombospondin-related adhesion pr otein gene, the dihydrofolate reductase gene, and the 18S rRNA gene on 8 (4 outbreak and 4 sporadic) isolates showed non-random association among the human and animal alleles of the 4 different C. parvum gene loci. Associatio ns between these 2 parasite genotypes and different routes of cryptosporidi osis transmission such as zoonotic, anthroponotic, and waterborne transmiss ion were studied using municipal population and agricultural information, a s well as detection of C. parvum oocysts in municipal drinking water specim ens of the residential communities of sporadic and outbreak cases.