Cryptosporidium parvum Prevalence and Molecular Typing in Dairy Calves with Diarrhea in Córdoba, Argentina - Abstract
Cryptosporidiosis in calves is caused by the enteroprotozoan pathogen Cryptosporidium spp. The disease results in intense diarrhea associated with substantial economic losses in dairy farming worldwide. The objectives of this study were to determine calves, herd and within-herd Cryptosporidium prevalence; identify Cryptosporidium species and C. parvum subgenotypes in calves with diarrhea in intensive dairy herds in central Argentina. A total of 1073 fecal samples were collected from 54 dairy herds randomly selected. Samples were processed with formol-ether to concentrate Cryptosporidium oocysts and were detected by light microscopy using modified Ziehl-Neelsen technique. Positive samples were further analyzed to determine the infecting Cryptosporidium specie by PCR-RFLP of the 18S rRNA gene resulting in exclusive identification of Cryptosporidium parvum. The overall prevalence of C. parvum for all calves studied was 25.5% (95% C.I.: 22.9; 28.1%). Sequence analysis of the GP60 gene revealed 5 different subgenotypes (IIaA18G1R1, IIaA20G1R1, IIaA21G1R1, IIaA22G1R1, and IIaA24G1R1), all belonging to the zoonotic IIa family. The most commonly isolated subgenotypes in calves with diarrhea and high infection intensity were IIaA20G1R1 and IIaA18G1R1. The subgenotype IIaA24G1R1 is first reported. The most frequently found subgenotype IIaA18G1R1 in this study is implicated in zoonotic transmission, which combined with a high prevalence suggests that calves might be an important source for human cryptosporidiosis in Argentina.