Identification and characterization of a Chinese isolate of Cryptosporidium serpentis from dairy cattle.

Cryptosporidium serpentis, a protozoan observed first in snakes, has also been found in lizards and other reptiles. However, there are few reports of the characteristics of C. serpentis isolated from humans and other animals. The present study was undertaken to characterize a C. serpentis isolate from a calf in terms of morphology, host specificity, and small-subunit ribosomal RNA (SSU rRNA) and heat shock protein 70 (HSP 70) gene sequences. Oocysts of the isolate measured 6.32 × 5.18 μm, and they had a length/width shape index of 1.22. A cross-transmission study demonstrated that the isolate was infectious in the stomach of BALB/c mice, but not in New Zealand white rabbits or white leghorn chickens. Sequence and phylogenetic analysis of the SSU rRNA and HSP 70 gene revealed that the isolate was identical to C. serpentis, and it was classified in a monophyletic group of C. serpentis. This study is the first description of the characteristics of a C. serpentis isolate from dairy cattle and may contribute to a better understanding of C. serpentis and investigations of the prevalence of Cryptosporidium in cattle.