Nugent G, Whitford E J, Hunnam J C, Wilson P R, Cross M l, de Lisle G W
Landcare Research Manaaki Whenua, PO Box 40, Lincoln 7640, New Zealand.
N Z Vet J. 2011 Nov;59(6):293-8. doi: 10.1080/00480169.2011.605747.
To determine the prevalence of Mycobacterium avium subsp. paratuberculosis (Map) infection in wildlife, in pastoral landscapes with a recent history of clinical Johne's disease in livestock.
A total of 449 wild mammals and birds from three farms in the South Island of New Zealand with recent histories of clinical Johne's disease in their deer herds were trapped and examined for gross pathological changes in the gastrointestinal tract. Additionally, individual mesenteric lymph nodes from 380 mammals, and segments of gastrointestinal tract from 32 birds were excised, homogenised and cultured for viable Map bacilli. The prevalence of Map infection was then calculated for the various species. Faecal samples from those mammals which had culture-positive tissues were further cultured for the presence of Map.
Gross pathological changes were identified in the gastrointestinal tract of four brushtail possums, one cat, six ferrets, 12 hares, six hedgehogs, three rabbits, one stoat, and one paradise shelduck. Infection with Map in the gastrointestinal tract was confirmed in only three of these cases, one each of brushtail possums, hares and hedgehogs. In contrast, Map infection in the absence of gross pathological changes was frequently recorded in enteric tract tissues of mammals and birds. Among mammals, Map infection was recorded in 18/73 (25%) brushtail possums, 4/23 (17%) cats, 15/42 (36%) hedgehogs and 29/113 (26%) rabbits. Among birds, intestinal tract tissue Map infection was recorded in 3/17 (18%) paradise shelducks. Among 64 of the 74 mammals which had Map culture-positive tissues, 38% (n=5) of hedgehogs and 11% (n=3) of rabbits also had culture-positive faecal samples.
This study is the first to identify that Map infection can be prevalent in wildlife in New Zealand. There was a high prevalence of Map infection among both scavenging and grazing wild animals. Both mammals and birds are capable of harbouring viable Map organisms in their gastrointestinal tract; further, viable Map was excreted into the environment via faeces by hedgehogs and rabbits.
Previous studies overseas have postulated a role of wildlife as reservoirs of Map infection and possible vectors of Johne's disease to livestock. Here, brushtail possums, hedgehogs and rabbits and in particular were identified as potential wildlife hosts for Map infection in New Zealand. This suggests that several wildlife species could contribute to the persistence of Map infection within a wildlife/livestock complex, and potentially, perhaps more importantly, to the spread of infection between farms.
确定在近期有牲畜临床型副结核病史的牧区景观中，野生动物感染副结核分枝杆菌亚种副结核菌（Map）的患病率。
对新西兰南岛三个农场的449只野生哺乳动物和鸟类进行诱捕，这些农场的鹿群近期有临床型副结核病史，并检查其胃肠道的大体病理变化。此外，切除380只哺乳动物的单个肠系膜淋巴结和32只鸟类的胃肠道段，匀浆并培养以检测是否存在活的Map杆菌。然后计算不同物种的Map感染患病率。对那些组织培养呈阳性的哺乳动物的粪便样本进一步培养以检测是否存在Map。
在4只帚尾袋貂、1只猫、6只雪貂、12只野兔、6只刺猬、3只兔子、1只白鼬和1只黄嘴黑鸭的胃肠道中发现了大体病理变化。其中只有3例确诊胃肠道感染Map，分别为1只帚尾袋貂、1只野兔和1只刺猬。相比之下，在没有大体病理变化的情况下，在哺乳动物和鸟类的肠道组织中经常记录到Map感染。在哺乳动物中，18/73（25%）的帚尾袋貂、4/23（17%）的猫、15/42（36%）的刺猬和29/113（26%）的兔子被记录有Map感染。在鸟类中，3/17（18%）的黄嘴黑鸭肠道组织有Map感染。在74只Map培养呈阳性的哺乳动物中，64只中有38%（n = 5）的刺猬和11%（n = 3）的兔子粪便样本培养也呈阳性。
本研究首次确定Map感染在新西兰野生动物中可能很普遍。在食腐和食草野生动物中Map感染患病率都很高。哺乳动物和鸟类在其胃肠道中都能够携带活的Map生物体；此外，刺猬和兔子通过粪便将活的Map排泄到环境中。
海外先前的研究推测野生动物作为Map感染的储存宿主以及副结核病可能向牲畜传播的媒介的作用。在此，帚尾袋貂、刺猬和兔子尤其被确定为新西兰Map感染的潜在野生动物宿主。这表明几种野生动物物种可能有助于Map感染在野生动物/牲畜复合体中持续存在，并且潜在地，也许更重要的是，有助于感染在农场之间传播。
