Asymptomatic Cryptosporidium infections in ewes and lambs are a source of environmental contamination with zoonotic genotypes of Cryptosporidium parvum
Résumé
Cryptosporidiosis, caused by protozoan parasites of the Cryptosporidium genus, is responsible for severe disease in new-born lambs. However, asymptomatic infections are frequently found in lambs and are the rule in ewes. The most commonly detected Cryptosporidium species in sheep are C. ubiquitum, C. xiaoi and C. parvum (including the zoonotic IId and IIa genotypes of this latter species). Because poor information on lambs cryptosporidiosis is available in France, a cross-sectional survey of five dairy sheep farms from Southwestern France was conducted during winter 2017-2018. Individual fecal samples were collected from 93 female lambs (10 to 15 days old) and from their mothers (80 ewes). These lambs and ewes were equally distributed into the five farms. All samples were screened using Bailenger concentration method and PCR targeting SSU rRNA 18S for Cryptosporidium spp detection. Positive PCR samples were further genotyped by GP60 PCR analysis. No clinical cryptosporidiosis case was observed in the 93 lambs during the survey. By using the Bailenger method, Cryptosporidium spp. oocysts were detected in lambs in only one farm and in ewes in three farms with low prevalences (5.3% in lambs and from 10.1 to 11.8% in ewes). By contrast, Cryptosporidium spp. DNA was detected in the feces of 15 ewes (with prevalences ranged from 10 to 33% according to the farm) and in 35 lambs (with prevalences ranged from 0 to 72.2%). Cryptosporidium parvum was the most commonly detected species in both young lambs and ewes, whatever the farm. Only zoonotic IId and IIa genotypes were identified when genotyping was possible. C. ubiquitum and C. xiaoi were detected in one and three farms respectively. Based on these findings, healthy young lambs and their mothers (at least just after lambing) could represent a source of environmental contamination with zoonotic genotypes of C. parvum species.
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