Spinacia oleracea L. Leaf Stomata Harboring Cryptosporidium parvum Oocysts: a Potential Threat to Food Safety

Abstract

Cryptosporidium parvum is a cosmopolitan microscopic protozoan parasite that causes severe diarrheal disease (cryptosporidiosis) in mammals, including humans and livestock. There is growing evidence of Cryptosporidium persistence in fresh produce that may result in food-borne infection, including sporadic cases as well as outbreaks. However, drinking and recreational waters are still considered the major sources of Cryptosporidium infection in humans, which has resulted in prioritization of studies of parasite etiology in aquatic environments, while the mechanisms of transmission and parasite persistence on edible plants remain poorly understood. Using laser scanning confocal microscopy together with fluorescein-labeled monoclonal antibodies, C. parvum oocysts were found to strongly adhere to spinach plants after contact with contaminated water, to infiltrate through the stomatal openings in spinach leaves, and to persist at the mesophyll level. These findings and the fact that this pathogenic parasite resists washing and disinfection raise concerns regarding food safety.

Effect of Chlorine, Blanching, Freezing, and Microwave Heating on Cryptosporidium parvum Viability Inoculated on Green Peppers

“…Cryptosporidium's resistance to chlorine has also been reported in other studies (8,15). Furthermore, because Cryptosporidium oocysts have been shown to be internalized through the stomata and because they resist hours of washing, the risk of not eliminating Cryptosporidium oocysts from contaminated vegetables by chlorinated washing bath is even greater (16,19). These findings have implications for the safety of minimally processed and ready-to-eat vegetables as these products are assumed to be safe and free of pathogens by the consumers who do not further wash the products before consumption.…”

Interaction Forces Drive the Environmental Transmission of Pathogenic Protozoa

“…Parasite-particle complexes exhibit a greater specific gravity and cannot be readily separated by flotation (55,90,98), whereas particles can also mask the antigenic sites at the parasite surface, thus hampering the antigen recognition by specific antibodies that are used for IMS or immunofluorescence techniques. The use of dispersant solutions, chelating agents, detergents, or biosurfactants is not always successful in preventing unwanted parasite-particle interactions during sample processing (54,75). Furthermore, the surfaces of purified parasites may be still coated with divalent cations and organic substances (humic and fulvic acids) that may interfere with downstream applications such as PCR, which usually give useful information on the species, viability, and genetic type of the detected parasites (41,58,102).…”

New Insights of Microsporidial Infection among Asymptomatic Aboriginal Population in Malaysia

“…Alternatively, it may be that microsporidia spores are capable of strong adhesion to or internalization in, certain types of product, thereby successfully evading the effects of washing and disinfection. A research conducted in the USA demonstrated that Cryptosporidium oocysts were capable of strongly adhering to spinach plants after contact with contaminated water and were also internalized within the leaves, thus making washing entirely ineffective [54].…”