Cryptosporidium parvum has been identified as a major cause of diarrhea and diarrhea-associated deaths in young children and neonatal calves. Infections can remain asymptomatic but may lead to malnutrition and persistent growth retardation. To assess the relationship between C. parvum genetic diversity and pathogenicity in neonatal dairy calves and determine the cause of diarrhea among these calves, 232 fecal samples from neonatal dairy calves on 12 farms in Xinjiang, China, were characterized

more »

... or Cryptosporidium presence based on the small subunit rRNA gene. The Cryptosporidium prevalence was 38.4% (89/232), and three species were detected with restriction fragment length polymorphism analysis, including C. parvum (the significantly dominant species), C. ryanae, and C. bovis. Cryptosporidium prevalence was significantly higher in neonatal dairy calves with diarrhea (52.6%, 51/97) than in calves without diarrhea (28.1%, 38/135). All C. parvum-positive samples were analyzed based on the 60 KDa glycoprotein gene, and IIdA15G1, IIdA20G1, IIdA14G1, and IIdA19G1 were successfully subtyped. These data indicate that C. parvum may be a major contributor to diarrheal disease in neonatal dairy calves, and C. parvum subtypes from neonatal dairy calves in Xinjiang exhibited high genetic diversity.