Cryptosporidium spp. are enteric protozoan parasites that infect a wide range of hosts including humans, and domestic and wild animals. The aim of this study was to molecularly characterize the Cryptosporidium spp. found in calf faeces in Japan. A total of 80 pre-weaned beef and dairy calves' diarrhoeic faecal specimens were collected from nine different prefectures in Japan. A nested polymerase chain reaction targeting the small subunit 18S rRNA and GP60 genes were used to detect the Cryptosporidium genotypes and subtypes. 83.8% (67 out of 80) of the specimens were positive for Cryptosporidium spp.; Cryptosporidium was found in both beef and dairy calves. Cryptosporidium parvum was the predominant species, detected in 77.5% (31/40) of beef calves and 80% (32/40) of dairy calves. Cryptosporidium bovis was also detected, 5.0% (2/40) of dairy calves, and C. ryanae was also found 2.5% (1/40) of dairy calves. One mixed-species infection, 2.5% (1/40) was detected in a beef calf having C. parvum, and C. ryanae. We detected the most common subtype of C. parvum (i.e., IIaA15G2R1), as well as other subtypes (i.e., IIaA14G3R1, IIaA14G2R1, and IIaA13G1R1) that have not previously been detected in calves in Japan. Our results demonstrate the widespread diversity of Cryptosporidium infection in calves in Japan.

隐孢子虫属。是肠道原生动物寄生虫，可感染包括人类，家畜和野生动物在内的多种宿主。这项研究的目的是分子表征隐孢子虫属。在日本的小牛粪便中发现。从日本的9个不同地区收集了总共80个断奶前的牛肉和奶牛小腹泻性粪便标本。针对小亚基18S rRNA和GP60基因的巢式聚合酶链反应用于检测隐孢子虫的基因型和亚型。样本中有83.8％（80个样本中有67个）的隐孢子虫呈阳性。牛肉和奶牛犊中都发现隐孢子虫。小隐孢子虫是主要种类，在77.5％（31/40）的牛犊和80％（32/40）的牛犊中检出。还检测到牛隐孢子虫，5.0％（2/40）的乳牛犊和ry。C. ryanae还发现了2.5％（1/40）的乳牛犊。一个混合物种感染，2.5％（1/40）在具有小牛牛肉检测微小隐孢子虫，和C. ryanae。我们检测到了日本小牛最常见的小隐孢子虫亚型（即IIaA15G2R1）以及其他亚型（即IIaA14G3R1，IIaA14G2R1和IIaA13G1R1）。我们的结果证明了日本小牛隐孢子虫感染的广泛多样性。