Influence of pH, ion composition and carbohydrate recognition on the attachment of Cryptosporidium parvum to lamb's lettuce.

Cryptosporidiosis is a worldwide infection caused by the protozoan parasites Cryptosporidium spp., which are mainly transmitted directly from infected hosts but also indirectly through contaminated food and water. The disease poses significant health impacts, particularly to vulnerable populations such as young children, the elderly, and immunocompromised individuals, including those living with HIV/AIDS. Of the food-borne Cryptosporidium spp. outbreaks reported worldwide, consumption of leafy greens is frequently associated. The different physical and chemical properties of each type of leafy green may affect the parasites' ability to adhere to plant surfaces. Here, we focus on the attachment of Cryptosporidium parvum oocysts to the leaves of lamb's lettuce (Valerianella locusta) under different conditions and identify factors that facilitate or inhibit it. We investigated specific interactions through carbohydrate receptors and assessed nonspecific interactions by modulating pH levels and ionic content. The results showed that magnesium ions significantly reduced the attachment of C. parvum oocysts to the leaves of lamb's lettuce. In contrast, sodium ions and the oocysts' inherent negative surface charge significantly enhanced attachment. Furthermore, specific carbohydrate interactions involving sialic acid, galactose, mannose, and N-acetyl-glucosamine were essential for attachment. These results highlight the intricate interaction between C. parvum and lamb's lettuce and suggest that specific molecular bindings and electrostatic forces may facilitate parasite attachment. These privileged interactions could contribute to the durable persistence of oocysts on leaf surfaces, thereby increasing the likelihood of food transmission to humans. Such information is essential for food operators to build hazard analysis in the frame of Hazard Analysis and Critical Control Points (HACCP) studies.