Asymptomatic Cryptosporidium infections in ewes and lambs are a source of environmental contamination with zoonotic genotypes of Cryptosporidium parvum

Protozoan parasites of the Cryptosporidium genus cause severe cryptosporidiosis in newborn lambs. However, asymptomatic infections also occur frequently in lambs and ewes. In sheep, the most commonly detected Cryptosporidium species are C. ubiquitum, C. xiaoi and C. parvum. Due to a lack of relevant information about such infections in France, we investigated the situation on five dairy sheep farms in the Pyrenees-Atlantiques Department in south-western France in December 2017. Individual fecal samples were collected from 79 female lambs (5-17 days old) and their mothers (72 ewes). Oocysts were screened using Heine staining before and after Bailenger concentrations. Cryptosporidium species identification and genotyping were performed using real-time PCR and gp60 gene sequencing. No cases of clinical cryptosporidiosis were observed in the 79 lambs. Microscopically, Cryptosporidium spp. oocysts were observed in only one lamb on one farm (prevalence 1.3%) and one ewe on another farm (prevalence 1.4%). By contrast, Cryptosporidium spp. DNA was detected in 17 ewes (prevalence ranging from 10.5% to 50% depending on the farm) and in 36 lambs (prevalence ranging from 0% to 77.8% depending on the farm). Only zoonotic Cryptosporidium parvum IId and IIa genotypes were identified when genotyping was possible. Cryptosporidium ubiquitum and C. xiaoi were detected on one and three farms, respectively. We conclude that healthy young lambs and their mothers during the peripartum period could be a source of environmental contamination with oocysts. Les parasites protozoaires du genre Cryptosporidium provoquent une cryptosporidiose severe chez les agneaux nouveau-nes. Cependant, des infections asymptomatiques surviennent aussi frequemment chez les agneaux et les brebis. Chez les ovins, les especes de Cryptosporidium les plus couramment detectees sont C. ubiquitum, C. xiaoi et C. parvum. En raison d'un manque d'informations pertinentes sur ces infections en France, nous avons enquete sur la situation de cinq elevages ovins laitiers des Pyrenees-Atlantiques en decembre 2017. Des echantillons fecaux individuels ont ete collectes sur 79 agnelles (5 a 17 jours) et leurs meres (72 brebis). Les oocystes ont ete cribles en utilisant une coloration Heine avant et apres concentration par la technique de Bailenger. L'identification et le genotypage des especes de Cryptosporidium ont ete realises a l'aide de la PCR en temps reel et du sequencage du gene gp60. Aucun cas de cryptosporidiose clinique n'a ete observe chez les 79 agneaux. Au microscope, les oocystes de Cryptosporidium spp. n'ont ete observes que chez un agneau dans une ferme (prevalence 1,3 %) et chez une brebis dans une autre ferme (prevalence 1,4 %). En revanche, de l'ADN de Cryptosporidium spp. a ete detecte chez 17 brebis (prevalence allant de 10,5 % a 50 % selon les fermes) et chez 36 agneaux (prevalence variant de 0 % a 77,8 % selon les fermes). Seuls les genotypes zoonotiques de Cryptosporidium parvum IId et IIa ont ete identifies lorsque le genotypage etait possible. Cryptosporidium ubiquitum et C. xiaoi ont ete detectes respectivement dans une et trois fermes. Nous concluons que les jeunes agneaux en bonne sante et leurs meres, autour de l'agnelage, pourraient etre une source de contamination environnementale par les oocystes.