Epidemiological survey in Łęczyńsko-Włodawskie Lake District of eastern Poland reveals new evidence of zoonotic potential of Giardia intestinalis.

Faecal samples from 297 farm animals were collected from 18 households in distinct sites of the Łęczyńsko-Włodawskie Lake District of eastern Poland. They included samples from 86 cattle (Bos taurus), 84 pigs (Sus scrofa f. domestica), 81 sheep (Ovis aries), 10 horses (Equus caballus), and 36 dogs (Canis lupus familiaris). The samples were examined for the presence of Giardia intestinalis by the Direct Fluorescence Assay (DFA) and semi-nested PCR. All amplicons were sequenced on both strands. By DFA, cysts of Giardia spp. were detected in 66 of 297 faecal samples (22.2%). Positive specimens for Giardia spp. were derived from 29.8% of examined pigs, 21.0% of sheep, 18.6% of cattle, 10% of horses, and 19.4% of dogs. Based on the detection of the β-giardin gene by PCR, 39 (13.1%) of the 297 examined samples were recognized as positive. Detection of the presence of Giardia cysts by DFA test was overall significantly higher compared to PCR (p=0.0045). By PCR, Giardia was found in 28.1% of sheep, 11.6% of cattle, 10% of horses, 9.5% of pigs and 5.6% of dogs. Partial β-giardin gene sequences were obtained for 73.7% of the PCR positive samples. From sequenced samples derived from the studied animals, Giardia were identified as assemblage A (8 samples), B (1 sample) and E (18 samples). As assemblages A and B may be zoonotic, the farm animals living in eastern Poland could be regarded as a potential source of Giardia infection for humans.