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. 2023 Dec 1:5:100160.
doi: 10.1016/j.crpvbd.2023.100160. eCollection 2024.

Genetic characterisation of Cryptosporidium parvum in dairy cattle and calves during the early stages of a calving season

Paul M Bartley  1 , Johan H Standar  1 , Frank Katzer  1
Affiliations

Genetic characterisation of Cryptosporidium parvum in dairy cattle and calves during the early stages of a calving season

Paul M Bartley et al. Curr Res Parasitol Vector Borne Dis. .

Abstract

Cryptosporidium parvum is a causative agent of cryptosporidiosis, an infectious gastroenteritis in neonatal ruminants, which can be fatal in severe cases. The aim of this study was to determine the prevalence of infections in dairy cattle/calves during the early stages of a calving season and the species/genotypes of the Cryptosporidium present. Faecal samples collected from pre- and post-partum dams (n = 224) as well as calves from age ∼1 day onwards (n = 312) were examined. Oocysts were concentrated, DNA extracted and tested by Cryptosporidium 18S rRNA gene PCR and sequencing, while genotypes of C. parvum were determined by gp60 and VNTR analysis. Results showed that 31.3% and 30.4% of pre- and post-partum dams tested positive for Cryptosporidium, respectively. In the adults, C. parvum (n = 52), C. bovis (n = 4) and C. andersoni (n = 19) were identified, while in the calves 248 out of 312 (79.5%) were PCR-positive for C. parvum. The proportion of positive calf samples was significantly higher (P < 0.0001) than the proportion of positive adult cattle during the first seven weeks of the calving season. In adult cattle, three distinct gp60 genotypes were identified, a predominant genotype IIaA15G2R1 (n = 36) and genotypes IIaA15R1 (n = 2) and IIaA14G2R1 (n = 1). In the calves, only genotype IIaA15G2R1 was detected (n = 125). Although C. parvum was observed in adult cattle two weeks after the start of the calving season, the predominant genotypes were not detected until Week 4 in both adults and calves, meaning it is still unclear whether adult cattle are the initial source of C. parvum infections on the farm. Historically calves on this dairy farm demonstrated the IIaA19G2R1 genotype, which, has now clearly been replaced with the IIaA15G2R1 genotype that is now found in both adults and calves. During the study season, significantly higher levels of neonatal calf mortality were observed compared to the seasons before (P = 0.046) and after (P = 0.0002). This study has shown comparable levels of C. parvum infection in both pre- and post-partum dams but higher levels of infection in neonatal calves.

Keywords: Calves; Cattle; Cryptosporidium parvum; Dairy; Neonatal.

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Conflict of interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Given their role as Co-Editor, Frank Katzer had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Editor-in-Chief Professor Aneta Kostadinova.

Figures

Image 1
Graphical abstract
Fig. 1
Fig. 1
Numbers of C. parvum-positive samples in adult cattle and calves throughout the beginning of a calving season. Notes: aC. parvum gp60 genotype IIaA15R1 identified; bC. parvum gp60 genotype IIaA14G2R1 identified; *C. parvum gp60 genotype IIaA15G2R1 first identified (this is the only gp60 genotype identified from that point onwards). Abbreviations: AP, animals in pen, but samples were not collected; E, pen empty (no animals); NSF, animals in pen, but no samples were found; SC, samples collected but not analysed.
Fig. 2
Fig. 2
Percentage of C. parvum-positive calf samples over the first 19 weeks of the calving season.
Fig. 3
Fig. 3
Efficiency of individual Variable Number Tandem Repeat (VNTR) PCRs. Results from the calf samples, illustrating the percentage of reactions that generated clearly identifiable peaks for each of the VNTR loci.
See this image and copyright information in PMC

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