Prevalence, genetic characteristics, and zoonotic potential of Cryptosporidium species causing infections in farm rabbits in China.

To assess the prevalence and public health significance of rabbit cryptosporidiosis, a total of 1,081 fecal specimens were collected between October 2007 and April 2008 from rabbits on eight farms in five different areas in Henan Province, China, and were examined by microscopy after Sheather's sucrose flotation and modified acid-fast staining. The average infection rate of Cryptosporidium was 3.4% (37/1,081 samples). There was a significant association between the prevalence of Cryptosporidium and the age of animals (chi(2) = 57.13; P < 0.01); the prevalence of cryptosporidiosis in 1- to 3-month-old rabbits was the highest (10.9%). The Cryptosporidium species in microscopy-positive specimens were genotyped by sequence analyses of the 18S rRNA, 70-kDa heat shock protein (HSP70), oocyst wall protein (COWP), and actin genes and were subtyped by sequence analysis of the 60-kDa glycoprotein (gp60) gene. Only the Cryptosporidium rabbit genotype was identified, with 100% sequence identity to published sequences of the 18S rRNA, HSP70, COWP, and actin genes, and the strains belonged to three gp60 subtypes (VbA36, VbA35, and VbA29). In view of the recent finding of the Cryptosporidium rabbit genotype in human outbreak and sporadic cases, the role of rabbits in the transmission of human cryptosporidiosis should be reassessed.