Geographical segregation of Cryptosporidium parvum multilocus genotypes in Europe

Cryptosporidium parvum is a common enteric protozoan pathogen of humans and livestock. Multilocus genotyping based on simple sequence repeat polymorphisms has been used extensively to identify transmission cycles and to investigate the structure of Cryptosporidium parvum populations and of the related pathogen Cryptosporidium hominis. Using such methods, the zoonotic transmission of Cryptosporidium parvum has been shown to be epidemiologically important. Because different genetic markers have been used in different surveys, the comparison of Cryptosporidium genotypes across different laboratories is often not feasible. Therefore, few comparisons of Cryptosporidium populations across wide geographical areas have been published and our understanding of the epidemiology of cryptosporidiosis is fragmented. Here we report on the genotypic analysis of a large collection of 692 Cryptosporidium parvum isolates originating primarily from cattle and other ruminants from Italy, Ireland and Scotland. Because the same genotypic markers were used in these surveys, it was possible to merge the data. We found significant geographical segregation and a correlation between genetic and geographic distance, consistent with a model of isolation by distance. The presence of strong LD and positive I-A(S) values in the combined MLG dataset suggest departure from panmixia, with different population structures of the parasite prevailing in each country. (C) 2015 Elsevier B.V. All rights reserved.