Ollivett T L, Nydam D V, Bowman D D, Zambriski J A, Bellosa M L, Linden T C, Divers T J
Department of Clinical Sciences, Box 20, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2009 Apr;92(4):1643-8. doi: 10.3168/jds.2008-1474.
Cryptosporidium is a zoonotic protozoan that is most often diagnosed in association with diarrhea in 1- to 3-wk-old dairy calves. There are neither consistently effective nor approved antimicrobial drugs for treatment in animals. The objective of this study was to test nitazoxanide (NTZ) as a treatment for cryptosporidiosis in experimentally infected dairy calves. A randomized, controlled, and blinded trial was performed using Holstein bull calves obtained from a large commercial dairy. All births were attended by study personnel and calves were fed 4 L of heat-treated colostrum within 1 h of birth. Calves were randomly assigned to treatment or placebo group and maintained for a 32-feeding (16 d) study period. Twenty-three calves were enrolled with 3 lost to follow up. Thirteen calves were assigned to the treatment group and 7 calves to the placebo group. All calves were inoculated with 1 x 10(6) viable Cryptosporidium parvum oocysts at feeding 3. Treatment was a commercially available NTZ product and the placebo was the carrier of the same product. Nitazoxanide was administered at 1.5 g twice per day for 5 d. Nitazoxanide or placebo treatment began after feeding 10 and when the fecal score was greater than 1 out of 3. Outcome measurements included twice-daily fecal and health scores and a once-daily oocyst count by an immunofluorescent antibody assay. Data were analyzed by nonparametric and time-to-event methods. Measures of passive transfer of antibodies, initial body weight, and onset of oocyst shedding were not different between treatment and control calves. Eighty-five percent of the NTZ-treated calves stopped shedding oocysts by the end of the observation period whereas only 15% of the placebo group stopped shedding. The median number of feedings with a fecal score equal to 3 was 2 in the NTZ group while it was 6 in the placebo group. Calves receiving NTZ were 0.13 times as likely to have severe and sustained diarrhea than control calves (95% confidence interval, 0.02-0.98). Treating calves with NTZ reduced the duration of oocyst shedding and improved fecal consistency.
隐孢子虫是一种人畜共患的原生动物，最常与1至3周龄奶牛犊腹泻相关联而被诊断出来。目前尚无始终有效的或已获批准用于动物治疗的抗菌药物。本研究的目的是测试硝唑尼特（NTZ）对实验性感染奶牛犊隐孢子虫病的治疗效果。使用从一家大型商业奶牛场获取的荷斯坦公牛犊进行了一项随机、对照和盲法试验。所有犊牛出生时均有研究人员在场，犊牛在出生后1小时内喂食4升热处理初乳。犊牛被随机分配到治疗组或安慰剂组，并维持32次喂食（16天）的研究期。共纳入23头犊牛，3头失访。13头犊牛被分配到治疗组，7头犊牛被分配到安慰剂组。所有犊牛在第3次喂食时接种1×10⁶个活的微小隐孢子虫卵囊。治疗药物为一种市售的硝唑尼特产品，安慰剂为同一产品的载体。硝唑尼特以1.5克/天的剂量给药，每日2次，共5天。硝唑尼特或安慰剂治疗在第10次喂食后且粪便评分大于3分中的1分时开始。观察指标包括每日2次的粪便和健康评分以及通过免疫荧光抗体测定法每日1次的卵囊计数。数据采用非参数方法和事件发生时间方法进行分析。治疗组和对照组犊牛在抗体被动转移、初始体重和卵囊排出开始时间的指标上没有差异。到观察期结束时，85%接受硝唑尼特治疗的犊牛停止排出卵囊，而安慰剂组只有15%停止排出。硝唑尼特组粪便评分为3分的喂食次数中位数为2次，而安慰剂组为6次。接受硝唑尼特治疗的犊牛出现严重和持续性腹泻的可能性是对照犊牛的0.13倍（95%置信区间，0.02 - 0.98）。用硝唑尼特治疗犊牛可缩短卵囊排出持续时间并改善粪便稠度。
