Giardia duodenalis and Cryptosporidium spp. as contaminant protozoa of the main rivers of western Romania: genetic characterization and public health potential of the isolates

The objective of this study was to establish the prevalence, contamination level, and public health significance of Giardia duodenalis and Cryptosporidium spp. in the primary rivers of western Romania. A total of 53 sampling points in the 24 most important western Romanian rivers in four counties (Arad, Bihor, Caraș-Severin, and Timiș) were investigated from March to September 2016. Surface water samples were collected by microfiber filtration. Cryptosporidium and Giardia (oo)cysts were isolated using immunomagnetic separation (IMS) according to the USEPA 1623 method and, after staining with fluorescently labeled (FITC) monoclonal antibodies, were identified and counted under a microscope. The Cryptosporidium and Giardia (oo)cysts were identified to species and assemblage/sub-assemblage level through the nested PCR–RFLP procedure targeting the 18S ribosomal RNA and gdh genes, respectively. PCR-based techniques were utilized for all water samples. Overall, 22 samples (41.5%) were determined to be positive for Giardia cysts (ranging from 0.05 to 300 cysts per liter), and four samples (7.5%) tested positive for Cryptosporidium oocysts (0.17–48 oocysts/l). G. duodenalis was molecularly identified in 13 water samples (24.5%), indicating the presence of the sub-assemblage A-II (n = 12) and assemblage E (n = 1). PCR–RFLP showed that two samples (3.8%) contained Cryptosporidium DNA, and the identified species were Cryptosporidium parvum and Cryptosporidium canis. All positive results were successfully confirmed by DNA sequencing. Subtyping of the zoonotic C. parvum isolate based on sequence analysis of the GP60 gene revealed the occurrence of the IIaA16G1R1 subtype. The results of this study highlight considerable contamination of river waters with pathogenic Giardia spp. and Cryptosporidium spp., suggesting a potential risk for the public and animal health. This report presents the first extended published description of the presence of Giardia spp. and Cryptosporidium spp. in the aquatic environment in Romania.