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Cryptosporidium facts
Multilocus analysis of Cryptosporidium hominis and Cryptosporidium parvum
isolates from sporadic and outbreak-related human cases and C. parvum isolates
from sporadic livestock cases in the United Kingdom.
Leoni F, Mallon ME, Smith HV, Tait A, McLauchlin J.
J Clin Microbiol. 2007 Oct;45(10):3286-94. Epub 2007 Aug 8
Cryptosporidium parvum and Cryptosporidium hominis isolates from sporadic, drinking water-associated, and
intrafamilial human cases together with C. parvum isolates from sporadic cases in livestock were collected in
the United Kingdom between 1995 and 1999. The isolates were characterized by analysis of three
microsatellite markers (ML1, GP15, and MS5) using PCR amplification. Within C. hominis, four alleles were
detected within the GP15 and MS5 loci, and a single type was detected with ML1. C. parvum was more
polymorphic; 12 alleles were detected with GP15, 6 were detected with MS5, and 3 were detected with ML1.
Multilocus analysis of polymorphisms within the three microsatellite loci was combined with those reported
previously for an extrachromosomal small double-stranded RNA. Forty multilocus types were detected within
these two species: 9 were detected in C. hominis, and 31 were detected in C. parvum. In C. hominis,
heterogeneity was almost exclusively found in samples from sporadic cases. Similarity analysis identified
three main groups within C. parvum, and the group that predominated in human infection was also found in
livestock. Multilocus types of C. parvum previously identified only in humans were not detected in livestock.
Isolates of both C. hominis and C. parvum from separate waterborne outbreaks were genetically
homogeneous, suggesting preferential or point source transmission of certain types of these two species of
parasites.