Parvum Infection Research Articles

Effects of Enterococcus faecalis CECT 7121 on Cryptosporidium parvum infection in mice.

Cryptosporidium is an opportunistic protozoan parasite of humans and animals worldwide and causes diarrheal disease that is typically self-limiting in immunocompetent hosts but often life threatening to immunocompromised individuals. However, there is a lack of completely efficient therapy available. Probiotics have attracted the attention as potential antiparasite compounds against protozoa involved in intestinal infections. This study investigated the effects of administration of probiotic Enterococcus faecalis CECT 7121 on Cryptosporidium parvum infection in immunosuppressed mice. Effects on C. parvum infection at the intestinal mucosa were studied and scored at each portion of the gut. It was demonstrated that Ef CECT 7121 interfered with C. parvum infection when both probiotic and parasite were present in the same intestinal location suggesting that Ef CECT 7121 supplementation can alleviate the negative effects of C. parvum infection.

Differential recognition of the multiple banded antigen isoforms across Ureaplasma parvum and Ureaplasma urealyticum species by monoclonal antibodies

Two separate species of Ureaplasma have been identified that infect humans: Ureaplasma parvum and Ureaplasma urealyticum. Most notably, these bacteria lack a cell wall and are the leading infectious organism associated with infection-related induction of preterm birth. Fourteen separate representative prototype bacterial strains, called serovars, are largely differentiated by the sequence of repeating units in the C-terminus of the major surface protein: multiple-banded antigen (MBA). Monoclonal antibodies that recognise single or small groups of serovars have been previously reported, but these reagents remain sequestered in individual research laboratories. Here we characterise a panel of commercially available monoclonal antibodies raised against the MBA and describe the first monoclonal antibody that cross-reacts by immunoblot with all serovars of U. parvum and U. urealyticum species. We also describe a recombinant MBA expressed by Escherichia coli which facilitated further characterisation by immunoblot and demonstrate immunohistochemistry of paraffin-embedded antigens. Immunoblot reactivity was validated against well characterised previously published monoclonal antibodies and individual commercial antibodies were found to recognise all U. parvum strains, only serovars 3 and 14 or only serovars 1 and 6, or all strains belonging to U. parvum and U. urealyticum. MBA mass was highly variable between strains, consistent with variation in the number of C-terminal repeats between strains. Antibody characterisation will enable future investigations to correlate severity of pathogenicity to MBA isoform number or mass, in addition to development of antibody-based diagnostics that will detect infection by all Ureaplasma species or alternately be able to differentiate between U. parvum, U. urealyticum or mixed infections.

Oregano Essential Oil and Carvacrol reduce Cryptosporidium parvum infectivity of HCT‐8 Cells

Lipid‐based nutrition supplements (LNS) are commonly used to treat moderate acute undernutrition in children. However, existing LNS products mainly focus on providing nutrients and do not address other immediate causes of undernutrition, such as parasitic infection and gut inflammation. Enteric parasites are known to reduce nutrient digestion and absorption, cause chronic gut inflammation, iron deficiency anemia, protein‐energy malnutrition, and reduce growth and cognitive development in children. Oregano essential oil (OEO) is known to have anti‐bacterial and anti‐fungal activity, however its anti‐parasitic properties are poorly understood. This study systemically investigated the effect of OEO and its main bioactive, carvacrol (CV), on prevention of Cryptosporidium parvum infectivity of HCT‐8 (human colon carcinoma) cells in vitro, for potential incorporation of these bioactives into LNS products. HCT‐8 cells were seeded (1 × 106) in 96‐well microtiter plates until confluency (2 days). HCT‐8 cell viability at various concentrations of either OEO or CV was measured using a Live/Dead cell imaging kit. Confluent HCT‐8 cell monolayers were seeded with C. parvum oocytes (1 × 104) in two modalities: 1) 4 h co‐culture of C. parvum oocysts, cells and several dosages (0 μg/mL to 250 μg/mL) of CV or OEO in complete medium, followed by PBS washing and replacement with bioactive‐free media; and 2) 4 h co‐culture of C. parvum oocysts and cells alone, followed by PBS washing and treatment with several dosages (0 μg/mL to 250 μg/mL) of CV or OEO. In either modality, plates were incubated at 37°C and 5% CO2, and after 2‐day incubation, cells and C. parvum were fixed with methanol: acetic acid solution (9:1 v/v). Infectivity was assessed via immunofluorescence detection using C. parvum‐specific antibody staining (Sporo‐Glo™) and phase contrast/fluorescent microscopy. Deformation of cell monolayers and loss of cell viability was found at 50 μg/mL CV, whereas no loss in cell viability was observed in cells treated with OEO at dosages as high as 125 μg/mL (containing similar concentrations of CV). In modality 1 experiments, cells simultaneously treated with C. parvum and various dosages of OEO or CV presented similar amounts of infection after 4 h incubation as those cells treated with C. parvum alone. In modality 2 experiments, after 2‐day treatment with bioactives, a 50% reduction in C. parvum infectivity was observed at 25 μg/mL of CV and at 125 μg/mL of OEO. C. parvum is one of the most resilient enteric parasites and prevalent in most of the developing world. Incorporation of OEO or CV into LNS formulas may provide double benefit to at risk populations afflicted by undernutrition and gut infection living in low‐income settings.Support or Funding InformationIndian Council of Agricultural Research (ICAR), India

Lymphocytic Interstitial Pneumonitis: An Unusual Presentation of X-Linked Hyper Ig M Syndrome.

Lymphocytic Interstitial Pneumonitis: An Unusual Presentation of X-Linked Hyper Ig M Syndrome.

Genotyping of Cryptosporidium Species and Their Clinical Manifestations in Patients with Renal Transplantation and Human Immunodeficiency Virus Infection.

In the present study we aimed to determine (i) frequency of Cryptosporidium species among patients with renal transplantation (RT) and human immunodeficiency virus (HIV) infection and (ii) relationship of the nature, severity, and duration of symptoms with different species and load of Cryptosporidium. Stool samples from 70 (42 RT and 28 HIV) and 140 immunocompromised patients with and without cryptosporidiosis by modified Kinyoun's staining were subjected to qPCR-melting curve analysis for identification of parasite species. qPCR detected one microscopically negative sample to be positive for cryptosporidiosis. C. hominis, C. parvum, and mixed infection were detected in 50/71 (70.4%), 19/71 (26.8%), and 2/71 (2.8%) patients, respectively. Patients with cryptosporidiosis had higher stool frequency (median, IQR: 4, 3–6/d versus 3, 2–4/d; P = 0.017) and watery stool (52/71 [73%] versus 64/139 [46%]; P = 0.003). Parasite load (median, IQR: Log10 6.37 (5.65–7.12), Log10 5.81 (4.26–6.65); P = 0.046) and nausea/vomiting (29/50 [58%] versus 5/19 [26%]; P = 0.032) were more frequent with C. hominis than with C. parvum infection. Thus, Cryptosporidium spp. (mainly C. hominis) is a common cause of diarrhoea in RT and HIV patients.

Dynamics of Th17 associating cytokines in Cryptosporidium parvum-infected mice.

Cryptosporidium parvum commonly inhabits the intestinal tract of animals and humans and can cause acute watery diarrhea and weight loss. However, host immune responses to Cryptosporidium infections are not fully understood. IL-17 (also called IL-17A) is a pro-inflammatory cytokine of Th17 cells that plays a role in the host response to Cryptosporidium baileyi infection. The present study examined levels of IL-17-specific messenger RNA (mRNA) and Th17 associating cytokines in C. parvum-infected immune-suppressed BALB/c mice using real-time quantitative PCR (qPCR). Levels of IL-17 protein were determined by ELISA. The results showed that levels of IL-17 mRNA and Th17 cell-related cytokines, namely TGF-β, IL-6, STAT-3, RORγt, IL-22, TNF-α, and IL-23, were significantly increased (P < 0.05) in gut-associated lymphoid tissue (GALT) and spleen. IL-17 protein levels in GALT were also significantly increased (P < 0.05) after infection. The present study suggested that Th17 cells play a role in host-C. parvum interaction. These results could inform future studies of the immune response against C. parvum infection in transient immunosuppressed populations.

SHP-2 Mediates Cryptosporidium parvum Infectivity in Human Intestinal Epithelial Cells.

The parasite, Cryptosporidium parvum, induces human gastroenteritis through infection of host epithelial cells in the small intestine. During the initial stage of infection, C. parvum is reported to engage host mechanisms at the host cell-parasite interface to form a parasitophorous vacuole. We determined that upon infection, the larger molecular weight proteins in human small intestinal epithelial host cells (FHs 74 Int) appeared to globally undergo tyrosine dephosphorylation. In parallel, expression of the cytoplasmic protein tyrosine phosphatase Src homology-2 domain-containing phosphatase 2 (SHP-2) increased in a time-dependent manner. SHP-2 co-localized with the C. parvum sporozoite and this interaction increased the rate of C. parvum infectivity through SH2-mediated SHP-2 activity. Furthermore, we show that one potential target that SHP-2 acts upon is the focal adhesion protein, paxillin, which undergoes moderate dephosphorylation following infection, with inhibition of SHP-2 rescuing paxillin phosphorylation. Importantly, treatment with an inhibitor to SHP-2 and with an inhibitor to paxillin and Src family kinases, effectively decreased the multiplicity of C. parvum infection in a dose-dependent manner. Thus, our study reveals an important role for SHP-2 in the pathogenesis of C. parvum. Furthermore, while host proteins can be recruited to participate in the development of the electron dense band at the host cell-parasite interface, our study implies for the first time that SHP-2 appears to be recruited by the C. parvum sporozoite to regulate infectivity. Taken together, these findings suggest that SHP-2 and its down-stream target paxillin could serve as targets for intervention.

Prevalence of Cryptosporidium parvum infection in adult with acute diarrhea referred to clinical laboratories in Jahrom by Nested PCR, 2014

Prevalence of Cryptosporidium parvum infection in adult with acute diarrhea referred to clinical laboratories in Jahrom by Nested PCR, 2014

Oleylphosphocholine (OlPC) arrests Cryptosporidium parvum growth in vitro and prevents lethal infection in interferon gamma receptor knock-out mice.

Cryptosporidium parvum is a species of protozoa that causes cryptosporidiosis, an intestinal disease affecting many mammals including humans. Typically, in healthy individuals, cryptosporidiosis is a self-limiting disease. However, C. parvum can cause a severe and persistent infection that can be life-threatening for immunocompromised individuals, such as AIDS patients. As there are no available treatments for these patients that can cure the disease, there is an urgent need to identify treatment options. We tested the anti-parasitic activity of the alkylphosphocholine oleylphosphocholine (OlPC), an analog of miltefosine, against C. parvum in in vitro and in vivo studies. In vitro experiments using C. parvum infected human ileocecal adenocarcinoma cells (HCT-8 cells) showed that OlPC has an EC50 of 18.84 nM. Moreover, no cell toxicity has been seen at concentrations ≤50 μM. C57BL/6 interferon gamma receptor knock-out mice, were infected by gavage with 4000 C. parvum oocysts on Day 0. Oral treatments, with OlPC, miltefosine, paromomycin or PBS, began on Day 3 post-infection for 10 days. Treatment with OlPC, at 40 mg/kg/day resulted in 100% survival, complete clearance of parasite in stools and a 99.9% parasite burden reduction in the intestines at Day 30. Doses of 30 and 20 mg/kg/day also demonstrated an increased survival rate and a dose-dependent parasite burden reduction. Mice treated with 10 mg/kg/day of miltefosine resulted in 50% survival at Day 30. In contrast, control mice, treated with PBS or 100 mg/kg/day of paromomycin, died or had to be euthanized between Days 6 and 13 due to severe illness. Results of parasite burden were obtained by qPCR and cross-validated by both flow cytometry of stool oocysts and histological sections of the ileum. Together, our results strongly support that OlPC represents a potential candidate for the treatment of C. parvum infections in immunocompromised patients.

Health benefits of Il-10 egg yolk antibodies administered to milk-fed dairy calves

Cryptosporidium parvum infection in calves causes villous atrophy, resulting in reduced surface area and absorptive capacity of the small intestine. Prevention and treatment of C. parvum infections are hindered by a lack of approved, efficacious products and inadequate colostral immunity. An integral component of infection is the dampening of the cell-mediated response by inducing anti-inflammatory cytokines. In calves, ileal intraepithelial lymphocytes express interleukin-10 (Il-10) when infected with C. parvum. Interleukin-10 decreases production of interferon-gamma, which is a vital Thl-associated cytokine. Studies have shown that Il-10 knockout mice are resistant to C. parvum infection. Oral administration of chicken egg yolk antibodies as a means of controlling enteric disease in calves is of interest to the dairy industry. Egg yolk Il-10 antibodies have been shown to survive gastrointestinal transit, are accessible in the intestinal lumen, and remain locally active, without persistence of systemic residues. Therefore, the objective of this trial was to investigate the effect of feeding Il-10 antibodies on calf health and performance after natural C. parvum infection in pre-weaned Holstein dairy calves.

Heparin interacts with elongation factor 1α of Cryptosporidium parvum and inhibits invasion.

Cryptosporidium parvum is an apicomplexan parasite that can cause serious watery diarrhea, cryptosporidiosis, in human and other mammals. C. parvum invades gastrointestinal epithelial cells, which have abundant glycosaminoglycans on their cell surface. However, little is known about the interaction between C. parvum and glycosaminoglycans. In this study, we assessed the inhibitory effect of sulfated polysaccharides on C. parvum invasion of host cells and identified the parasite ligands that interact with sulfated polysaccharides. Among five sulfated polysaccharides tested, heparin had the highest, dose-dependent inhibitory effect on parasite invasion. Heparan sulfate-deficient cells were less susceptible to C. parvum infection. We further identified 31 parasite proteins that potentially interact with heparin. Of these, we confirmed that C. parvum elongation factor 1α (CpEF1α), which plays a role in C. parvum invasion, binds to heparin and to the surface of HCT-8 cells. Our results further our understanding of the molecular basis of C. parvum infection and will facilitate the development of anti-cryptosporidial agents.

Bovine TLR2 and TLR4 mediate Cryptosporidium parvum recognition in bovine intestinal epithelial cells

Cryptosporidium parvum (C. parvum) is an intestinal parasite that causes diarrhea in neonatal calves. It results in significant morbidity of neonatal calves and economic losses for producers worldwide. Innate resistance against C. parvum is thought to depend on engagement of pattern recognition receptors. However, the role of innate responses to C. parvum has not been elucidated in bovine. The aim of this study was to evaluate the role of TLRs in host-cell responses during C. parvum infection of cultured bovine intestinal epithelial cells. The expressions of TLRs in bovine intestinal epithelial cells were detected by qRT-PCR. To determine which, if any, TLRs may play a role in the response of bovine intestinal epithelial cells to C. parvum, the cells were stimulated with C. parvum and the expression of TLRs were tested by qRT-PCR. The expression of NF-κB was detected by western blotting. Further analyses were carried out in bovine TLRs transfected HEK293 cells and by TLRs-DN transfected bovine intestinal epithelial cells. The results showed that bovine intestinal epithelial cells expressed all known TLRs. The expression of TLR2 and TLR4 were up-regulated when bovine intestinal epithelial cells were treated with C. parvum. Meanwhile, C. parvum induced IL-8 production in TLR2 or TLR4/MD-2 transfected HEK293 cells. Moreover, C. parvum induced NF-κB activation and cytokine expression in bovine intestinal epithelial cells. The induction of NF-κB activation and cytokine expression by C. parvum were reduced in TLR2-DN and TLR4-DN transfected cells. The results showed that bovine intestinal epithelial cells expressed all known TLRs, and bovine intestinal epithelial cells recognized and responded to C. parvum via TLR2 and TLR4.

Prevalence and molecular characterization of Cryptosporidium spp. in dairy cattle, northwest China.

Cryptosporidium spp. cause enteric diseases in a wide range of animals, including dairy cattle. However, limited information is available regarding prevalence and molecular characterization of Cryptosporidium spp. in dairy cattle in Gansu province and Ningxia Hui Autonomous Region (NXHAR), northwest China. A total of 2945 dairy feces samples (1257 from Gansu province and 1688 from NXHAR) were collected between December 2012 and March 2014 and were tested by PCR amplification of the small subunit (SSU) rRNA gene. A total of 150 (5.09%, 58 from Gansu and 92 from NXHAR) samples were PCR-positive for Cryptosporidium, and the prevalence is associated with the region and age of dairy cattle. Species identification showed Cryptosporidium andersoni in 36 samples (24.00%, 19 from NXHAR and 17 from Gansu), Cryptosporidium ryanae in 24 samples (16.00%, 13 from NXHAR and 11 from Gansu), Cryptosporidium bovis in 70 samples (46.67%, 41 from NXHAR and 29 from Gansu), and Cryptosporidium parvum in 20 samples (13.33%, 19 from NXHAR and 1 from Gansu). A DNA sequence analysis of the gp60 gene suggested that all the 20 C. parvum isolates represented subtype IIdA15G1. These findings indicated the presence of zoonotic Cryptosporidium in Gansu and NXHAR. This is the first report of four species of Cryptosporidium (C. andersoni, C. ryanae, C. bovis, and C. parvum) infection in dairy cattle in Gansu province. This is also the first report of C. ryanae infection in dairy cattle in NXHAR. Effective control strategies should be implemented to prevent and control Cryptosporidium infection in dairy cattle and humans.

The Occurrence of Cryptosporidium parvum in Dairy Calves and the Influence of Management Practices

Cryptosporidium species infections are associated with the clinical manifestation of diarrhea, which can possibly generate economic losses associated with morbidity and mortality depending on the type of property management used. Additionally, animals with diarrhea eliminate large quantities of oocysts via the feces, thus contributing to the dispersion of oocysts in the environment and favoring the infection of susceptible hosts. The study aimed to determine the rate of Cryptosporidium parvum infection in 79 calves under one year of age at a dairy farm in southern Rio de Janeiro state, Brazil, in association with the cattle raising management practices. During the study period, two different management practices (A and B) were adopted. Under practice A, 21.9% of the samples (7/32) were Cryptosporidium spp. positive according to microscopic diagnosis. After switching to practice B, the percentage of infected animals decreased to 8.5% (4/47). Although diarrhea was reported in 13.9% (11/79) of the calves studied, there was no correlation with Cryptosporidium spp. infection (p>0.05). Cryptosporidium parvum, which is considered to have high zoonotic potential, was identified in this study. This fact is of great importance with regard to public health because of the environmental contamination of the area surrounding the property, which increases the risk to both human and animal populations. Additionally, the implementation of some changes in farm management practices contributed to a decrease in the percentage of infected animals, thereby reducing the dissemination of oocysts in the environment.

CCL20 Displays Antimicrobial Activity Against Cryptosporidium parvum, but Its Expression Is Reduced During Infection in the Intestine of Neonatal Mice.

CCL20 is a chemokine with antimicrobial activity. We investigated its expression and role during neonatal cryptosporidiosis, a worldwide protozoan enteric disease leading to severe diarrhea. Surprisingly, during infection by Cryptosporidium parvum, CCL20 production by the intestine of neonatal mice is reduced by a mechanism independent both of the enteric flora and of interferon γ, a key cytokine for the resolution of this infection. However, oral administration of recombinant CCL20 to neonatal mice significantly reduced the parasite load by a mechanism that was independent of immune cell recruitment and occurred instead by direct cytolytic activity on free stages of the parasite. MiR21 functionally targets CCL20 and is upregulated during the infection, thus contributing to the downregulation of the chemokine. Our findings demonstrate for the first time the direct antiparasitic activity of CCL20 against an enteric protozoan and its downregulation during C. parvum infection, which is detrimental to parasite clearance.

Cryptosporidium parvum infection among Egyptian school children.

The present study determined cryptosporidiosis among 120 randomly chosen school children aged 4-16 years. Medical sheets were filled out on each child. The fresh stool samples were examined by using Sheather's sugar flotation stained with modified Ziehl Neelsen stain. Blood samples were examined by ELISA and IFA techniques. The results revealed that, the prevalence rate was 13.51% with a peak among the age group (5-10) and. significant relation between males and females. There was a significant relation between infection and low socio-economic level in rural area. Also, a significant relation was obtained between the infection and the presence of animal contact. Watery and loose diarrhea was more significant among infected children. Positive stool samples were among 37 (30.8 %), while ELISA and IFA detected 30 (25%) and 33 (27.5%) respectively. The validity test of ELISA declared sensitivity and specificity with 93.3% and 90% while IFA declared 90.9% and 91.1% respectively.

Sa1776 Decreased SLC26A3 Expression and Function in Intestinal Epithelial Cells in Response to Cryptosporidium parvum Infection

Sa1776 Decreased SLC26A3 Expression and Function in Intestinal Epithelial Cells in Response to Cryptosporidium parvum Infection

Genes expressed in grapevine leaves reveal latent wood infection by the fungal pathogen Neofusicoccum parvum.

Some pathogenic species of the Botryosphaeriaceae have a latent phase, colonizing woody tissues while perennial hosts show no apparent symptoms until conditions for disease development become favorable. Detection of these pathogens is often limited to the later pathogenic phase. The latent phase is poorly characterized, despite the need for non-destructive detection tools and effective quarantine strategies, which would benefit from identification of host-based markers in leaves. Neofusicoccum parvum infects the wood of grapevines and other horticultural crops, killing the fruit-bearing shoots. We used light microscopy and high-resolution computed tomography (HRCT) to examine the spatio-temporal relationship between pathogen colonization and anatomical changes in stem sections. To identify differentially-expressed grape genes, leaves from inoculated and non-inoculated plants were examined using RNA-Seq. The latent phase occurred between 0 and 1.5 months post-inoculation (MPI), during which time the pathogen did not spread significantly beyond the inoculation site nor were there differences in lesion lengths between inoculated and non-inoculated plants. The pathogenic phase occurred between 1.5 and 2 MPI, when recovery beyond the inoculation site increased and lesion lengths of inoculated plants tripled. By 2 MPI, inoculated plants also had decreased starch content in xylem fibers and rays, and increased levels of gel-occluded xylem vessels, the latter of which HRCT revealed at a higher frequency than microscopy. RNA-Seq and screening of 21 grape expression datasets identified 20 candidate genes that were transcriptionally-activated by infection during the latent phase, and confirmed that the four best candidates (galactinol synthase, abscisic acid-induced wheat plasma membrane polypeptide-19 ortholog, embryonic cell protein 63, BURP domain-containing protein) were not affected by a range of common foliar and wood pathogens or abiotic stresses. Assuming such host responses are consistent among cultivars, and do not cross react with other trunk/foliar pathogens, these grape genes may serve as host-based markers of the latent phase of N. parvum infection.

Molecular characterization of Cryptosporidium spp. among children in rural Ghana.

BackgroundThe relevance of Cryptosporidium infections for the burden of childhood diarrhoea in endemic settings has been shown in recent years. This study describes Cryptosporidium subtypes among symptomatic and asymptomatic children in rural Ghana to analyse subtype-specific demographic, geographical, seasonal and clinical differences in order to inform appropriate control measures in endemic areas.Methodology/Principal FindingsStool samples were collected from 2232 children below 14 years of age presenting with and without gastrointestinal symptoms at the Agogo Presbyterian Hospital in the rural Ashanti region of Ghana between May 2007 and September 2008. Samples were screened for Cryptosporidium spp. by PCR and isolates were classified into subtypes based on sequence differences in the gp60 gene. Subtype specific frequencies for age, sex, location and season have been determined and associations with disease symptoms have been analysed within a case-control study. Cryptosporidium infections were diagnosed in 116 of 2232 (5.2%) stool samples. Subtyping of 88 isolates revealed IIcA5G3 (n = 26, 29.6%), IbA13G3 (n = 17, 19.3%) and IaA21R3 (n = 12, 13.6%) as the three most frequent subtypes of the two species C. hominis and C. parvum, known to be transmitted anthroponotically. Infections peak at early rainy season with 67.9% and 50.0% of infections during the months April, May and June for 2007 and 2008 respectively. C. hominis infection was mainly associated with diarrhoea (odds ratio [OR] = 2.4; 95% confidence interval [CI]: 1.2–4.9) whereas C. parvum infection was associated with both diarrhoea (OR = 2.6; CI: 1.2–5.8) and vomiting (OR = 3.1; 95% CI: 1.5–6.1).Conclusions/SignificanceCryptosporidiosis is characterized by seasonal anthroponotic transmission of strains typically found in Sub-Saharan Africa. The infection mainly affects young infants, with vomiting and diarrhoea being one of the leading symptoms in C. parvum infection. Combining molecular typing and clinical data provides valuable information for physicians and is able to track sources of infections.

Cryptosporidium parvum infection and associated risk factors in dairy calves in western France

This study was conducted to determine the prevalence and risk factors for Cryptosporidium infection in calf neonates on dairy farms in Normandy.Fecal samples were randomly collected between July 2010 and September 2011 from 968 calves (7–21 days old) on 97 farms. Up to 10 calves were selected and sampled per farm, and feces examined for oocysts by microscopy. C. parvum oocyst shedding was scored semi-quantitatively (0–5). A questionnaire about calf-level care and management was completed, and mortality rates were obtained from the French national registration database (BDNI). Bivariable and multivariable analyses of potential risk factors for C. parvum oocyst shedding were conducted using generalized estimating equation (GEE) models (family=Binomial).Overall, 402 out of 968 calves (41.5%) were positive for oocysts, and 25.1% of animals had a shedding score >2. Seven of the 97 farms (7%) were negative for oocysts in all fecal samples. At the time of collection, 375 calves (39%) had diarrhea, and its prevalence strongly correlated with the score for C. parvum oocyst shedding (p<0.0001). The mortality rate at 90 days was significantly greater for calves with high combined scores of diarrhea and shedding. Factors associated with the shedding of C. parvum were the Normande breed (odds ratio=1.49; 95% confidence interval (CI): 0.93–2.37), dispensing of colostrum using a bucket (odds ratio=1.37; 95% CI: 1.00–1.89), treatment with halofuginone (odds ratio=0.46; 95% CI: 0.19–1.15) and feeding with fermented milk (odds ratio=0.32; 95% CI: 0.17–0.63).C. parvum is widespread among calves under 21 days old in dairy herds of western France. Shedding of C. parvum is associated with a high incidence of diarrhea and increased risk of mortality in young calves. This study identified some associated calf-level factors, although further investigations are necessary to determine appropriate measures that farmers and veterinary practitioners should take to reduce the prevalence of C. parvum.