Cultural human-snake interactions in the festa dei serpari as an opportunity for the surveillance of bacterial pathogens of zoonotic concern

Reptiles harbour a wide range of pathogen species, some of which can pose risks to human health. Among them, snakes serve as valuable sentinels for monitoring pathogens, particularly in some cultural contexts where animal-human interactions offer a unique opportunity to delve into bacterial dynamics throughout the years. This is the case of the annual serpent ritual "festa dei serpari" in Cocullo, in central Italy renowned for the San Domenico snakes festival. This study conducted a retrospective analysis of a comprehensive database of bacterial pathogens associated with wild snakes captured during the ritual, from 2010 to 2023 (excluding 2020 and 2021). Using different sampling methods, comprising cloacal, oral, and cutaneous swabs, along with faecal material, a total of 563 biological samples were collected from 465 registered snakes harvested for this unique ritual. Samples were analysed to assess the prevalence of bacterial species on snakes and the potential risks to human health. Seventy bacterial species were identified using traditional growth media, molecular diagnosis, biochemical analyses, and mass spectrometry performed in two national reference institutes. Among the results, zoonotic and opportunistic bacteria such as Salmonella spp., Escherichia coli, and drug-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae were of particular concern. The results also revealed significant trends during the years under investigation, with an increasing prevalence of Gram-negative bacteria and Staphylococcus sciuri, along with a decline in Salmonella spp. Our findings emphasize the importance of continued surveillance of zoonotic pathogens, given the close human-snake interactions that occur during this Sacro-profane historical ritual.