Pulford D J, McFadden Amj, Hamilton J S, Donald J
a Investigation and Diagnostic Centre , Ministry for Primary Industries , 66 Ward Street, Wallaceville, Upper Hutt 5018 , New Zealand.
b School of Biological Sciences , Victoria University of Wellington , PO Box 600, Wellington 6140 , New Zealand.
N Z Vet J. 2016 Jan;64(1):21-8. doi: 10.1080/00480169.2015.1090355. Epub 2015 Nov 5.
On 7 September 2012 the Ministry for Primary Industries was notified of a dairy cow with regenerative anaemia (haematocrit (HCT) 0.08 L/L) in a herd of 465 Jersey-Friesian cross cows (index case herd) in the Northland region of New Zealand. Organisms consistent with Theileria spp. were present in red blood cells on a blood smear. No other causes of anaemia were detected following examination of affected cows. Blood samples collected from 29 randomly selected cows on 26 September 2012 showed that 24 (83%) were anaemic (HCT≤0.24 L/L) and therefore fitted the case definition for bovine anaemia associated with Theileria orientalis infection.
Using a T. orientalis type-specific PCR assay that targeted the single subunit rRNA gene, all of six animals tested were positive for T. orientalis type Ikeda. Blood samples collected from clinically affected cattle in 11 subsequent outbreaks from throughout the North Island showed that T. orientalis Ikeda type was a common finding, but mixed infections with Chitose type were also identified. In addition, using a PCR assay that targeted the major piroplasm surface gene, T. orientalis type 5 was detected in one cow from the Waikato region.
The presence of T. orientalis type Ikeda, as well as type 5, was confirmed in cattle from outbreaks of bovine anaemia in herds throughout the North Island of New Zealand.
Two new types of T. orientalis were identified in this investigation, that were associated with a sudden rise in cases of bovine anaemia. The body of evidence showed that the Ikeda type was implicated as the cause of disease observed in this epidemic.
2012年9月7日，新西兰初级产业部接到报告，在北地地区一个拥有465头泽西-弗里生杂交奶牛的牛群中，有一头奶牛患有再生性贫血（血细胞比容（HCT）为0.08 L/L）（索引病例牛群）。血涂片显示红细胞内存在与泰勒虫属一致的生物体。对患病奶牛进行检查后，未发现其他贫血原因。2012年9月26日从29头随机挑选的奶牛采集的血样显示，24头（83%）贫血（HCT≤0.24 L/L），因此符合与东方泰勒虫感染相关的牛贫血病例定义。
使用针对单亚基rRNA基因的东方泰勒虫型特异性PCR检测方法，检测的6只动物全部为东方泰勒虫池田型阳性。从北岛随后11次疫情中临床患病牛采集的血样显示，东方泰勒虫池田型很常见，但也发现了与千岁型的混合感染。此外，使用针对主要梨形虫表面基因的PCR检测方法，在怀卡托地区的一头奶牛中检测到东方泰勒虫5型。
在新西兰北岛各牛群中爆发的牛贫血疫情的牛只中，证实存在东方泰勒虫池田型以及5型。
本次调查中鉴定出两种新型东方泰勒虫，它们与牛贫血病例的突然增加有关。证据表明，池田型是此次疫情中观察到的疾病病因。
