Feng Kangli, Li Na, Huang Yujin, Chen Chengyi, Wen Luxing, Wang Weijian, Ryan Una M, Xiao Lihua, Feng Yaoyu, Guo Yaqiong
Guangdong Laboratory for Lingnan Modern Agriculture, Center for Emerging and Zoonotic Diseases, College of Veterinary Medicine, South China Agricultural University, Guangzhou 510642, China.
Harry Butler Institute, Murdoch University, Western Australia, 6150, Australia.
Int J Parasitol. 2023 Oct;53(11-12):651-661. doi: 10.1016/j.ijpara.2023.04.005. Epub 2023 Jun 15.
Cryptosporidium bovis and Cryptosporidium ryanae are common species causing cryptosporidiosis in cattle. Data accumulated thus far indicate that the infection patterns of the two species could be different between areas with and without Cryptosporidium parvum. To better understand the infection dynamics of these two species, cross-sectional and longitudinal studies of Cryptosporidium spp. were conducted using genotyping and subtyping tools. In the cross-sectional survey, analysis of 634 faecal samples from two farms identified only C. bovis and C. ryanae in pre-weaned calves. Two birth cohorts of 61 and 78 calves were followed longitudinally over a 12 month period, which revealed the shedding of C. bovis oocysts started at 1-2 weeks of age and peaked initially at 6-8 weeks of age. Altogether calves experienced four infections by six subtype families of C. bovis, with each infection caused by different subtype families. In contrast, the shedding of C. ryanae oocysts started at 2-4 weeks of age, and the two infections were caused by different subtype families. The cumulative incidence of C. bovis infection was 100% (58/58, 32/32) on both farms, compared with 84.4-98.3% (27/32 and 57/58) for C. ryanae infection. Overall, the mean duration of oocyst shedding in the cohort studies was 3.8-4.0 weeks for C. bovis compared with 2.1 weeks for C. ryanae. The oocyst shedding intensity was high (mean oocysts per gram of faeces was over 10) during the first infection with each species but became significantly lower in the later infections. Cryptosporidium ryanae was associated with the occurrence of diarrhea on one farm, while C. bovis was not. The data indicate that there is an early occurrence of C. bovis and C. ryanae in pre-weaned calves with high infection intensity in the absence of C. parvum. Calves infected with the same Cryptosporidium sp. multiple times could be associated with the presence of subtype-specific immunity.
牛隐孢子虫和雷氏隐孢子虫是引起牛隐孢子虫病的常见种类。目前积累的数据表明，在有和没有微小隐孢子虫的地区，这两种隐孢子虫的感染模式可能有所不同。为了更好地了解这两种隐孢子虫的感染动态，利用基因分型和亚型分型工具对隐孢子虫进行了横断面和纵向研究。在横断面调查中，对来自两个农场的634份粪便样本进行分析，结果显示在断奶前的犊牛中仅发现了牛隐孢子虫和雷氏隐孢子虫。对两个出生队列的61头和78头犊牛进行了为期12个月的纵向跟踪，结果显示牛隐孢子虫卵囊的排出始于1至2周龄，最初在6至8周龄达到峰值。犊牛总共经历了由牛隐孢子虫的六个亚型家族引起的四次感染，每次感染由不同的亚型家族引起。相比之下，雷氏隐孢子虫卵囊的排出始于2至4周龄，两次感染由不同的亚型家族引起。两个农场中牛隐孢子虫感染的累积发病率均为100%（58/58，32/32），而雷氏隐孢子虫感染的累积发病率为84.4% - 98.3%（27/32和57/58）。总体而言，在队列研究中，牛隐孢子虫卵囊排出的平均持续时间为3.8 - 4.0周，而雷氏隐孢子虫为2.1周。在每种隐孢子虫的首次感染期间，卵囊排出强度很高（每克粪便中的平均卵囊数超过10个），但在随后的感染中显著降低。在一个农场中，雷氏隐孢子虫与腹泻的发生有关，而牛隐孢子虫则无关。数据表明，在没有微小隐孢子虫的情况下，断奶前犊牛中牛隐孢子虫和雷氏隐孢子虫早期出现且感染强度高。多次感染相同隐孢子虫种类的犊牛可能与亚型特异性免疫的存在有关。
