Prevalence and characterization of Cryptosporidium spp. in dairy cattle in Nile River delta provinces, Egypt

Molecular characterizations of Cryptosporidium spp. in dairy cattle in industrialized nations have mostly shown a dominance of Cryptosporidium parvum, especially its IIa subtypes in pre-weaned calves. Few studies, however, have been conducted on the distribution of Cryptosporidium species and C. parvum subtypes in various age groups of dairy cattle in developing countries. In this study, we examined the prevalence and molecular characteristics of Cryptosporidium in dairy cattle in four Nile River delta provinces in Egypt. Modified Ziehl-Neelsen acid-fast microscopy was used to screen for Cryptosporidium oocysts in 1974 fecal specimens from animals of different ages on 12 farms. Positive fecal specimens were identified from all studied farms with an overall prevalence of 13.6%. By age group, the infection rates were 12.5% in pre-weaned calves, 10.4% in post-weaned calves, 22.1% in heifers, and 10.7% in adults. PCR-RFLP and DNA sequence analyses of microscopy-positive fecal specimens revealed the presence of four major Cryptosporidium species. In pre-weaned calves, C. parvum was most common (30/69 or 43.5%), but Cryptosporidium ryanae (13/69 or 18.8%), Cryptosporidium bovis (7/69 or 10.2%), and Cryptosporidium andersoni (7/69 or 10.2%) were also present at much higher frequencies seen in most industrialized nations. Mixed infections were seen in 12/69 (17.4%) of genotyped specimens. In contrast, C. andersoni was the dominant species (193/195 or 99.0%) in post-weaned calves and older animals. Subtyping of C. parvum based on sequence analysis of the 60kDa glycoprotein gene showed the presence of subtypes IIdA20G1 in nine specimens, IIaA15G1R1 in 27 specimens, and a rare subtype IIaA14G1R1r1b in one specimen. The common occurrence of non-C. parvum species and IId subtypes in pre-weaned calves is a distinct feature of cryptosporidiosis transmission in dairy cattle in Egypt. The finding of the same two dominant IIa and IId C. parvum subtypes recently found in humans in Egypt suggests calves can be potential reservoirs of zoonotic cryptosporidiosis.