DETECTION AND PREVALENCE OF PROTOZOAN PARASITES IN READY-TO-EAT PACKAGED SALADS ON SALE IN ITALY.

Protozoan parasites commonly infect humans and animals, and numerous foodborne outbreaks associated with the consumption of fresh produce contaminated with Giardia duodenalis, Cryptosporidium spp., Cyclospora cayetanensis and Toxoplasma gondii have been reported worldwide. To investigate the prevalence of protozoans in ‘ready to eat’ (RTE) salads on sale in Italy, 648 packages were purchased from Industrial and Local brands. Nine individual packages from each brand were collected per month, pooled and subjected to microscopy and molecular analyses. 864 slides were microscopically examined to detect Cryptosporidium spp. and also Blastocystis hominis and Dientamoeba fragilis. Molecular tools identified G. duodenalis assemblage A, Cryptosporidium parvum and Cryptosporidium ubiquitum, T. gondii Type I and C. cayetanensis. B. hominis and D. fragilis were also molecularly confirmed. The overall prevalence of each protozoan species was 0.6% for G. duodenalis, 0.8 for T. gondii, 0.9% for Cryptosporidium spp., and 1.3% for C. cayetanensis, whereas the prevalence of B. hominis was 0.5% and that of D. fragilis 0.2%. Using microscopy and/or molecular tools, we found that 4.2% of the samples were contaminated by at least one protozoan species, and 0.6% of samples presented coinfections of two protozoan species, with a number of oocysts ranging from 62 to 554 per g of vegetable for T. gondii, and 46 to 1.580 for C. cayetanensis. This is the first large-scale study on the presence of protozoans in packaged salads in Europe. RTE sanitation processes from harvesting to packaging does not guarantee a product free from protozoans of fecal origin.