文献类型： 外文期刊

作者： Li, Na ¹ ; Wang, Rui ² ; Cai, Min ³ ; Jiang, Wen ² ; Feng, Yaoyu ¹ ; Xiao, Lihua ¹ ;

作者机构： 1.South China Agr Univ, Coll Vet Med, Minist Agr, Key Lab Zoonosis, Guangzhou 510642, Guangdong, Peoples R China

2.East China Univ Sci & Technol, Sch Resources & Environm Engn, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China

3.Shanghai Acad Agr Sci, Ecoenvironm Protect Inst, Shanghai 201403, Peoples R China

关键词： Cryptosporidium parvum; Outbreak; Dairy cattle; Diarrhea; Subtype

期刊名称：INTERNATIONAL JOURNAL FOR PARASITOLOGY （ 影响因子：3.981； 五年影响因子：4.214 ）

ISSN： 0020-7519

年卷期： 2019 年 49 卷 7 期

页码：

收录情况： SCI

摘要： Neonatal diarrhea is one of the most important syndromes in dairy cattle. Among enteropathogens, Cryptosporidium spp. are primary causes of diarrhea, but outbreaks due to cryptosporidiosis are rarely reported in cattle. From January to April in 2016, severe diarrhea was observed in over 400 neonatal dairy calves on a large dairy farm in Jiangsu Province of East China. Approximately 360 calves died due to watery diarrhea despite antibiotic therapy. In this study, 18 fecal specimens were collected from seriously ill calves on this farm during the diarrhea outbreak, and analysed for common enteropathogens by enzymatic immunoassay (EIA). In a post-outbreak investigation, 418 and 1372 specimens collected from animals of various age groups were further analysed for rotavirus and Cryptosporidium spp. by EIA and PCR, respectively, to assess their roles in the occurrence of diarrhea on the farm. Cryptosporidium spp. were genotyped using established techniques. Initial EIA tests showed that 15/18 seriously ill calves during the outbreak were positive for Cryptosporidium parvum, while 8/18 were positive for rotavirus. The overall infection rate of Cryptosporidium in pre-weaned calves on the farm was 22.7%, with odds of the Cryptosporidium infection during the outbreak 4.4-23.5 times higher than after the outbreak. Four Cryptosporidium spp. were identified after the outbreak including C. parvum (n = 79), Cryptosporidium ryanae (n = 48), Cryptosporidium bovis (n = 31), and Cryptosporidium andersoni (n = 3), with co-infections of multiple species being detected in 34 animals. Infection with C. parvum (73/79) was found in the majority of calves aged <= 3 weeks, consistent with the age of ill calves during the outbreak. All C. parvum isolates were identified as subtype IIdA19G1. In the post-outbreak investigation, C. parvum infection was associated with the occurrence of watery diarrhea in pre-weaned calves, C. ryanae infection was associated with moderate diarrhea in both pre- and post-weaned calves, while no association was identified between rotavirus infection and the occurrence of diarrhea. Results of logistic regression analysis further suggested that C. bovis infection might also be a risk factor for moderate diarrhea in calves. Thus, we believe this is the first report of a major outbreak of severe diarrhea caused by C. parvum IIdA19G1 in dairy calves. More attention should be directed toward preventing the dissemination of this virulent subtype in China. (C) 2019 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.