Stringer L A, Wilson P R, Heuer C, Hunnam J C, Mackintosh C G
Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand.
N Z Vet J. 2011 Sep;59(5):218-24. doi: 10.1080/00480169.2011.596182.
To assess the effect of vaccination against paratuberculosis (Johne's disease) on reactivity to diagnostic tests for bovine tuberculosis (Tb) in deer exposed to natural challenge with Mycobacterium avium subsp. paratuberculosis (Map), and to investigate Map infection as a factor in Tb test cross-reactivity at the herd level.
In Study 1, yearling deer (n=180 vaccinates and n=181 controls) were randomly selected from three commercial deer herds participating in a trial of a commercial vaccine against paratuberculosis. The deer were subjected to the comparative cervical skin test (CCT) for Tb at 44 weeks post-vaccination. Interpretation as a mid-cervical tuberculin skin test (MCT) was also recorded. Serum from deer positive to the CCT was collected 3-4 weeks after tuberculin injection and tested using the ELISA Tb test (ETB), with both standard and the modified-ETB interpretations. In Study 2, 102 herds were categorised as infected or uninfected with Map based on results of pooled faecal culture, and positive to MCT if one or more deer gave a positive reaction to the MCT following testing in 2005. Information on other potential risk factors for MCT reactivity was collected using a standardised questionnaire conducted on each farm. The data were analysed using a multivariable logistic regression model.
In Study 1, 79/180 (44%) vaccinates and 42/181 (23%) controls were positive to the MCT (p<0.001). Two vaccinates (1.1%) that were CCT-positive were both positive to the standard ETB and negative to the modified ETB. One of three CCT-positive controls was negative to the standard ETB, and the other two were positive; both controls were modified ETB-positive. In Study 2, significantly more MCT-positive (41/58; 71%) than MCT-negative (18/44; 41%) herds were infected with Map (p=0.003). The OR for a positive MCT for herds infected with Map was 3.1 (95% CI=1.3-7.5), compared with uninfected herds. Herd size was positively associated with a positive MCT result (p=0.004).
Infection with Map and vaccination increased the risk of non-specificity of the MCT in deer herds. The CCT and ancillary testing of CCT-positive animals using the modified ETB are effective tools to address the reduced specificity of the MCT. However, where use of these tests is not permitted, non-specificity related to infection and vaccination will be more difficult to resolve.
评估针对副结核病（约翰氏病）的疫苗接种对暴露于鸟分枝杆菌副结核亚种（Map）自然感染的鹿对牛结核病（Tb）诊断检测反应性的影响，并调查Map感染作为畜群水平Tb检测交叉反应性的一个因素。
在研究1中，从参与一种商业副结核病疫苗试验的三个商业鹿群中随机选取一岁龄鹿（180只接种疫苗的鹿和181只对照鹿）。在接种疫苗后44周，对这些鹿进行牛结核病的比较颈皮试验（CCT）。还记录了作为颈中部结核菌素皮试（MCT）的解读结果。在结核菌素注射后3 - 4周收集CCT呈阳性的鹿的血清，并用ELISA牛结核病检测（ETB）进行检测，包括标准和改良ETB解读。在研究2中，根据粪便混合培养结果，将102个畜群分为感染或未感染Map的类别，并且如果在2005年检测后有一只或多只鹿对MCT呈阳性反应，则该畜群对MCT呈阳性。使用在每个农场进行的标准化问卷收集关于MCT反应性的其他潜在风险因素的信息。数据使用多变量逻辑回归模型进行分析。
在研究1中，79/180（44%）接种疫苗的鹿和42/181（23%）对照鹿对MCT呈阳性（p<0.001）。两只CCT呈阳性的接种疫苗的鹿（1.1%）对标准ETB呈阳性且对改良ETB呈阴性。三只CCT呈阳性的对照鹿中有一只对标准ETB呈阴性，另外两只呈阳性；两只对照鹿对改良ETB均呈阳性。在研究2中，感染Map的MCT呈阳性的畜群（41/58；71%）显著多于MCT呈阴性的畜群（18/44；41%）（p = 0.003）。与未感染的畜群相比，感染Map的畜群MCT呈阳性的比值比为3.1（95%可信区间 = 1.3 - 7.5）。畜群规模与MCT阳性结果呈正相关（p = 0.004）。
Map感染和疫苗接种增加了鹿群中MCT非特异性的风险。CCT以及使用改良ETB对CCT阳性动物进行辅助检测是解决MCT特异性降低的有效工具。然而，在不允许使用这些检测的情况下，与感染和疫苗接种相关的非特异性将更难解决。
