Ready-to-eat salads and berry fruits purchased in Italy contaminated by Cryptosporidium spp., Giardia duodenalis, and Entamoeba histolytica

Abstract

Ready-to-eat (RTE) salads and berries are increasingly consumed in industrialized countries. These products can be contaminated by pathogenic parasites that have been responsible for foodborne outbreaks worldwide. In Italy, there are few data on contamination of RTE salads and berries with parasite transmission stages and this requires more-in-depth investigations. To estimate the prevalence of contamination with Cryptosporidium spp. and Giardia duodenalis in these fresh products, a total of 324 packages of local RTE mixed salads - belonging to three different industrial brands - and 324 packages of berries - blueberries from Peru, blackberries from Mexico, raspberries from Italy - were bought from supermarkets located in the Provinces of Bari and Foggia, Apulia, Italy. A pool size of nine packages was chosen and a total of 72 pools were processed in the whole year. After washing, the pellets were examined by microscopy (FLOTAC) and tested using conventional simplex PCR, targeting Cryptosporidium spp., Giardia duodenalis, and Entamoeba spp., and sequencing. Several Cryptosporidium species and Giardia duodenalis assemblages, some of which are of potential zoonotic relevance, as well as Entamoeba spp., were identified in both matrices. By microscopy, Giardia-like cysts in local raspberries and Entamoeba-like cysts in imported blueberries were detected. Giardia duodenalis (Assemblages A, B and E) and Entamoeba histolytica were molecularly confirmed with overall prevalences of 4.6% (95% C.I. 3.0-6.8) and 1% (95% C.I. 0.3-2.1), respectively. Molecular methods identified Cryptosporidium ryanae, Cryptosporidium bovis, Cryptosporidium xiaoi, and Cryptosporidium ubiquitum in both matrices, with a prevalence of 5.1% (95% C.I. 3.3-7.3). A distinct seasonality in prevalence was observed for G. duodenalis, with most positives occurring in spring, whereas Cryptosporidium showed no significant seasonal variations. These results highlight that inadequate management of fresh produce, both locally produced and imported, along the food chain may have the potential for consequences on human health.

Keywords: Contamination; FLOTAC; Fresh produce; PCR; Prevalence; protozoa.