Protozoa as the “Underdogs” for Microbiological Quality Evaluation of Fresh Vegetables

Abstract

The monitoring of the microbial quality of fresh products in the industrial environment has mainly focused on bacterial indicators. Protozoa, such as Giardia duodenalis, Cryptosporidium spp., Toxoplasma gondii, and Cyclospora cayetanensis, are routinely excluded from detection and surveillance systems, despite guidelines and regulations that support the need for tracking and monitoring these pathogens in fresh food products. Previous studies performed by our laboratory, within the scope of the SafeConsume project, clearly indicated that consumption of fresh produce may be a source of T. gondii, thus posing a risk for the contraction of toxoplasmosis for susceptible consumers. Therefore, preliminary work was performed in order to assess the microbiological quality of vegetables, highlighting not only bacteria (Escherichia. coli, Listeria monocytogenes, and Salmonella spp.), but also the zoonotic protozoa G. duodenalis and Cryptosporidium spp. Although all samples were found to be acceptable based on bacteriological parameters, cysts of G. duodenalis and oocysts of Cryptosporidium spp. were observed in vegetables. Moreover, it was possible to genetically characterize G. duodenalis positive samples as assemblage A, a genotype that poses risks to human health. Although these are preliminary results, they highlight the need to include protozoa in the microbiological criteria for foodstuffs, as required by EU Law No. 1441/2007, and to improve inactivation and removal procedures of (oo)cysts in fresh produce and water.

Investigating the Occurrence of Soil-Transmitted Parasites Contaminating Soil, Vegetables, and Green Fodder in the East of Nile Delta, Egypt

“…Many research papers show the preponderance of Giardia among protozoa parasites tested on fresh food at the farm, which is comparable with our findings [ 10 , 57 ]. The low infective dose of these parasites and their ability to replicate inside human host has been linked to several food-borne outbreaks, particularly in the developed countries [ 58 ], prompting international food safety agencies to develop a standard International Organization for Standardization (ISO) protocol for identifying them in leafy greens and berry fruits [ 59 ]. The altered epidemiological situation caused by the interaction of agriculture border expansion, natural ecosystem changes, and the introduction of animal species for food production all had a significant impact on the prevalence of these protozoa in humans [ 24 , 60 ].…”

Protozoan parasites and free-living amoebae contamination in organic leafy green vegetables and strawberries from Spain

“…T. gondii is only found in cats and wild felids, while C. cayetanensis is only found in humans. Cysts and oocysts have the capacity to remain viable for an extended period in the environment due to their structure, which protects them in exogenous stages ( Marques et al, 2022 ). Moreover, outdoor vegetable cultivation allows the access of animals (both domestic and wild), which can defecate in the fields and, therefore, be a source of contamination ( Maffei et al, 2016 ).…”