Abstract
Cryptosporidium and Giardia protozoa are zoonotic parasites that cause human gastroenteritis and can be transmitted to human through the fecal-oral route and water or food. Several species belong to these genera and their resistant forms occur in water, but only some of them are infectious to human. Health risk depends on the occurrence of infectious Cryptosporidium and Giardia species and genotypes in water, and only molecular techniques allow detecting them, as well as enable to identify the contamination source. In this work, genotyping and phylogenetic analysis have been performed on the basis of 18S rDNA and ß-giardin genes sequences of Cryptosporidium and Giardia, respectively, in order to provide the molecular characterization of these parasites detected earlier in five natural water bodies in Poland and to track possible sources of their (oo)cysts in water. Genotyping revealed a high similarity (over 99 up to 100 %) of analyzed sequences to cattle genotype of C. parvum isolated from cattle and human and to G. intestinalis assemblage B isolated from human. The sequences obtained by others originated from patients with clinical symptoms of cryptosporidiosis or giardiasis and/or with the infection confirmed by different methods. The contamination of three examined lakes is probably human-originated, while the sources of contamination of two remaining lakes are wild and domestic animals. Obtained phylogenetic trees support suggestions of other authors that the bovine genotype of C. parvum should be a separate species, as well as A and B assemblages of G. intestinalis.