Epidemiology and diagnostics of intestinal parasitic infections in Italy: a multicentric survey

Background and Aims: parasitic infections are becoming more common in non-endemic countries because of intensified immigration and international travels; however, the parasitic disease burden is often underestimated because of underdiagnosis and lack of surveillance in industrialized countries. Also, in Italy, epidemiological data on intestinal parasites affecting humans are scarce and scattered in different areas of the country. The aim of this retrospective, observational study was to evaluate the prevalence of intestinal parasitic infections employing Parasitological Stool Examination (PSE) and to verify the quality of the diagnostic methodologies adopted to identify intestinal parasites in Italian laboratories. Materials and Methods: the study involved 28 Italian diagnostic laboratories and 36389 patients, from June 2015 to May 2016. Results: our data showed that 3173 out of 36389 subjects (8.7%) were carriers of one or more pathogenic or non-pathogenic protozoa or helminths. When only organisms known to cause intestinal disease were considered, an overall positive rate of 3.8% was found (1400/36389). Among the 1400 patients carrying one or more pathogenic species, protozoan infections predominated and were identified in 1138 subjects (3.1%); Dientamoeba fragilis and Giardia duodenalis represent the main intestinal pathogens. Concerning parasitic worms, only 262 individuals (0.7%) exhibited helminth infection; the most frequent finding was represented by Enterobius vermicularis, followed by Taenia spp. Conclusions: this survey also indicated that not all diagnostic laboratories can guarantee proper performance for parasitological diagnosis. In this context, close collaboration between physicians and clinical microbiologists is warranted to improve the diagnostics of intestinal parasitic infections, thus ensuring good quality service.