Frequency and molecular identification of Cryptosporidium spp in confined suckling dairy calves in Aguascalientes, Mexico

Abstract

In order to determine the frequency of Cryptosporidium spp and to identify the species or genotype of oocysts found in confined, suckling lactating calves in Aguascalientes, Mexico dairies, fecal samples were collected from 8-14-d old-calves in eight different dairies. Samples were smeared, Kinyoun-stained and subjected to nested PCR in order to amplify parasite's 18S rRNA region (830 bp). Positive samples were cloned on a pGEM-T vector then sequenced. Frequency of animals positive to Cryptosporidium spp by microscopy was 75 % (95/126), with a 25 to 100 % range among dairies, even though, using molecular techniques the frequency of positive animals was 67 % (85/126), with a 20 to 100 % range among dairies. All other samples were negative to both tests. All samples sequenced had a 100 % homology with the 18S rRNA region of C. parvum. Results confirm the relevance of C. parvum as a major etiology of cryptosporidiosis in suckling dairy calves and show its broad distribution in the area. Given that C. parvum is a zoonotic species, calf managers should be considered as broadly exposed to the infection.