Molecular detection of Blastocystis from animals in Italy: subtypes distribution and implications for the zoonotic transmission

Background: Blastocystis is a common intestinal protist distributed worldwide infecting humans and a wide range of domestic and wild animals. It exhibits an extensive genetic diversity and so far, 26 subtypes (STs) have been identified in animal hosts, ten of them (ST1-ST9 and ST12) reported in humans with varying prevalence. Since several STs are common to humans and animals it has been proposed that a proportion of human infections may have a zoonotic origin. Aims of the present study were to: 1) genetically detect Blastocystis in faecal samples of farmed animals and wild carnivores; 2) investigate the distribution of Blastocystis STs in different animal hosts; 3) provide a first study on the Blastocystis STs circulating between animals and humans in Italy.Methods: Fresh faecal samples (N=269) were collected from carnivores and farmed animals in different Italian provinces and submitted to genomic DNA extraction and PCR amplification followed by both sequence and phylogenetic analysis (Neighbour Joining and Maximum Parsimony)Results: Blastocystis was detected in 50% of the farmed animals (42 out of 84), and 19 of them were successfully subtyped. Conversely, all the faecal samples (N=185) from domestic and wild carnivores (dogs, cats, foxes) tested in the present study, resulted negative. Phylogenetic analysis showed the finding of ST5, ST7, ST9 and ST10 in the samples from animals. The comparison with sequences of Blastocystis STs previously detected from humans in Italy showed the ST7, as a potential source of zoonotic transmission.Conclusions: The present study represents the widest epidemiological survey so far performed in animals in Italy. Further epidemiological studies using molecular approaches are required to determine the occurrence and distribution of Blastocystis STs in other potential animal reservoirs and to define the pathways of zoonotic transmission.