Cross-border investigations on the prevalence and transmission dynamics of Cryptosporidium species in dairy cattle farms in western mainland Europe

Cryptosporidium is comprised an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis. In cattle farms, the incidence of cryptosporidiosis results in high mortality in calves leading to considerable economic loss in the livestock industry. Infected animals may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in calves. This poses a significant risk to other farms via breeding centres, to trading of livestock and to human health. This study, funded by the Interreg-2-seas programme, is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, 1084 faecal samples, corresponding to 57 dairy-farms from all three countries, were analysed. Well-established protocols amplifying the 18S rDNA and gp60 genes fragments, followed by DNA sequencing, were used for the detection and subtyping C. parvum; the DNA sequences obtained were further characterised using a combination of bioinformatics and phylogenetics methods. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also detected in humans. Consequently, this study highlights how widespread is C. parvum in dairy farms and endorses cattle as a major carrier of zoonotic C. parvum subtypes, which subsequently pose a significant threat to human health.