Norton S, Corner L A L, Morris R S
EpiCentre, Massey University, Private Bag 11222, Palmerston North, New Zealand.
N Z Vet J. 2005 Oct;53(5):293-300. doi: 10.1080/00480169.2005.36563.
To quantify the duration of survival of possums (Trichosurus vulpecula) infected with Mycobacterium bovis, and identify aspects of their behaviour which may influence the likelihood of disease transmission to domestic stock or wildlife.
Capture and den locations of 14 naturally infected tuberculous possums, eight possums experimentally infected with M. bovis and eight non-infected possums were recorded between May 1998 and February 2000 at a study site near Castlepoint on the Wairarapa coast of the North Island in New Zealand. Denning behaviour was observed weekly using radiotelemetry, and possums were captured, examined and released bi-monthly. Data were used to estimate survival period; create denning, activity, and total ranges; and to identify extended forays by possums as individuals and groups.
Seventeen tuberculous possum carcasses were recovered, of which 14 (82%) were close to or within their activity range. Denning ranges were known for 10/17 possums that died. Four tuberculous possums were found dead within their denning range. Three possums made extended forays in the 3 weeks before death. Twelve possums were found dead in dense scrub, three in long grass in open woodland and two on pasture. Mean duration of survival of naturally infected possums following detection of clinical signs was 3.4 months (95% CI=2.1-5.4) and the instantaneous mortality rate was 0.293 per month (95% CI=0.184-0.470). Signs of disease were obvious for about 3 weeks prior to death. Tuberculous possums were commonly trapped on only part of the area where the total non-infected population was trapped.
Most tuberculous possums died within their activity range and in scrub, representing a risk of transmission of M. bovis to wildlife and livestock that forage in scrub. Smaller proportions dying on pasture represent a less frequent, but highly visible risk. Tuberculous possums were clustered on the study site, and localised possum control operations would be more effective if focussed on such areas.
量化感染牛分枝杆菌的负鼠（帚尾袋貂）的存活时长，并确定其行为中可能影响疾病传播到家畜或野生动物的可能性的方面。
1998年5月至2000年2月期间，在新西兰北岛怀拉拉帕海岸卡斯尔波因特附近的一个研究地点，记录了14只自然感染结核病的负鼠、8只经实验感染牛分枝杆菌的负鼠和8只未感染负鼠的捕获地点和巢穴位置。每周使用无线电遥测技术观察筑巢行为，每两个月捕获、检查并放生负鼠。数据用于估计存活期；创建筑巢、活动和总范围；并识别负鼠作为个体和群体的远距离外出活动。
找回了17具结核病负鼠尸体，其中14具（82%）靠近或在其活动范围内。已知10/17只死亡负鼠的筑巢范围。4只结核病负鼠在其筑巢范围内被发现死亡。3只负鼠在死亡前3周进行了远距离外出活动。12只负鼠在茂密灌木丛中被发现死亡，3只在开阔林地的长草丛中死亡，2只在牧场上死亡。自然感染负鼠出现临床症状后的平均存活时长为3.4个月（95%置信区间=2.1-5.4），瞬时死亡率为每月0.293（95%置信区间=0.184-0.470）。死亡前约3周疾病症状明显。结核病负鼠通常只在捕获未感染负鼠的区域的一部分被捕获。
大多数结核病负鼠在其活动范围内和灌木丛中死亡，这代表着牛分枝杆菌传播给在灌木丛中觅食的野生动物和家畜的风险。在牧场上死亡的比例较小，代表着风险虽不常见但非常明显。结核病负鼠聚集在研究地点，如果将局部负鼠控制行动集中在这些区域会更有效。
