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

Léa Bordes,Pauline Houert,Loïc Favennec,Damien Costa,Romy Razakandrainibe,Corinne Vial-Novella,Philippe Jacquiet,Christelle Grisez,Francis Fidelle,Françoise Prévot

doi:10.1051/parasite/2020054

Abstract

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 Pyrénées-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.

Highlights

Cryptosporidium spp. are ubiquitous protozoan parasites, responsible for the gastrointestinal disease cryptosporidiosis
Results showed a low prevalence of animals infected with the parasite: oocysts were detected in only one lamb (1.3%) on farm #5 and one ewe (1.4%) on farm #2
Molecular characterization showed that C. ubiquitum infected the lamb; identification of the Cryptosporidium species infecting the ewe was unsuccessful due to an unreadable sequence

Summary

Introduction

Cryptosporidium spp. are ubiquitous protozoan parasites, responsible for the gastrointestinal disease cryptosporidiosis. Infection with Cryptosporidium oocysts can be acquired through (i) the fecal-oral route, (ii) contaminated water or food, or (iii) aerosolized droplets or by contact with fomites contaminated by coughing [35] Some species, such as Cryptosporidium parvum, appear to lack host specificity as they can be found in a wide range of hosts. Vermeulen and colleagues [49] estimated the Cryptosporidium oocyst loads in livestock manure and predicted that it was the main source of environmental contamination in Europe and North America Without adequate control, this contamination represents a human health hazard, because animals infected with C. parvum could be excreting up to 107 oocysts per gram of feces [11]

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