Number of Cryptosporidium parvum oocysts or Giardia spp cysts shed by dairy calves after natural infection
Number of Cryptosporidium parvum oocysts or Giardia spp cysts shed by dairy calves after natural infection
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DOI：
10.2460/ajvr.2001.62.1612
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发表时间：
2001-10-01
影响因子：
1
通讯作者：
Mohammed, HO
中科院分区：
文献类型：
--
作者：
Nydam, DV;Wade, SE;Mohammed, HO
试验-确定自然感染后最危险时期内，乳牛排出的隐孢子虫卵囊和贾第鞭毛虫包囊的总数。动物-自然感染隐孢子虫卵囊的478头乳牛和自然感染贾第鞭毛虫包囊的1，016头乳牛。程序-从粪便标本中计数卵囊或包囊。卵囊或包囊数量随年龄的分布用于确定最佳拟合数学函数。通过确定曲线下面积计算给定脱落持续时间内每克粪便的卵囊或包囊数。卵囊或包囊的总数计算采取的产物和预期的质量feces.Results-Intensity的C parvum卵囊脱落最好的二阶多项式函数描述的产品。从4日龄开始，脱落增加，在第12天达到峰值，然后下降。一头6日龄感染的小牛将产生3.89 × 10（10）个卵囊，直到12日龄。指数函数最好地描述了贾第鞭毛虫包囊的脱落模式。脱落强度从4日龄开始增加，在14日龄达到峰值，然后下降。从第50天到第56天，受感染的小牛将产生3.8 × 10（7）个包囊。结论和临床意义-大量的卵囊和包囊脱落表明奶牛的脱落对易感小牛和人构成风险。这里报告的估计数可能有助于设计具有成本效益的战略来管理这一风险。
Objective-To determine the total number of Cryptosporidium parvum oocysts and Giardia spp cysts shed by dairy calves during the period when they are most at risk after natural infection.Animals-478 calves naturally infected with C parvum and 1,016 calves naturally infected with Giardia spp.Procedure-Oocysts or cysts were enumerated from fecal specimens. Distribution of number of oocysts or cysts versus age was used to determine the best fitting mathematic function. Number of oocysts or cysts per gram of feces for a given duration of shedding was computed by determining the area under the curve. Total number of oocysts or cysts was calculated by taking the product of the resultant and the expected mass of feces.Results-Intensity of C parvum oocyst shedding was best described by a second-order polynomial function. Shedding increased from 4 days of age, peaked at day 12, and then decreased. An infected 6-day-old calf would produce 3.89 X 10(10) oocysts until 12 days old. Pattern of shedding of Giardia spp cysts was best described by exponential functions. Intensity of shedding increased from 4 days of age, peaked at day 14, and then decreased. An infected calf would produce 3.8 X 10(7) cysts from day 50 until day 56.Conclusions and Clinical Relevance-The large number of oocysts and cysts shed indicates that shedding by dairy cattle poses a risk for susceptible calves and people. Estimates reported here may be useful to aid in designing cost-effective strategies to manage this risk.