Donadio Josephine, Risely Alice, Müller-Klein Nadine, Wilhelm Kerstin, Clutton-Brock Tim, Manser Marta B, Sommer Simone
Institute for Evolutionary Ecology and Conservation Genomics, Albert-Einstein Allee 11, 89081 Ulm, Germany.
Large Animal Research Group, Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, United Kingdom.
J Wildl Dis. 2022 Apr 1;58(2):309-321. doi: 10.7589/JWD-D-21-00063.
Tuberculosis (TB) is an increasing threat to wildlife, yet tracking its spread is challenging because infections often appear to be asymptomatic, and diagnostic tools such as blood tests can be invasive and resource intensive. Our understanding of TB biology in wildlife is therefore limited to a small number of well-studied species. Testing of fecal samples using PCR is a noninvasive method that has been used to detect Mycobacterium bovis shedding amongst badgers, yet its utility more broadly for TB monitoring in wildlife is unclear. We combined observation data of clinical signs with PCR testing of 388 fecal samples to characterize longitudinal dynamics of TB progression in 66 wild meerkats (Suricata suricatta) socially exposed to Mycobacterium suricattae between 2000 and 2018. Our specific objectives were 1) to test whether meerkat fecal samples can be used to monitor TB; 2) to characterize TB progression between three infection states (PCR-negative exposed, PCR-positive asymptomatic, and PCR positive with clinical signs); and 3) estimate individual heterogeneity in TB susceptibility, defined here as the time between TB exposure and detection, and survival after TB detection. We found that the TB detection probability once meerkats developed clinical signs was 13% (95% confidence interval 3-46%). Nevertheless, with an adapted test protocol of 10 PCR replicates per sample we detected hidden TB infections in 59% of meerkats before the onset of clinical signs. Meerkats became PCR positive approximately 14 mo after initial exposure, developed clinical signs approximately 1 yr after becoming PCR positive, and died within 5 mo of developing clinical signs. Individual variation in disease progression was high, with meerkats developing clinical signs from immediately after exposure to 3.4 yr later. Overall, our study generates novel insights into wildlife TB progression, and may help guide adapted management strategies for TB-susceptible wildlife populations.
结核病（TB）对野生动物的威胁日益增加，但追踪其传播具有挑战性，因为感染往往看似无症状，而且血液检测等诊断工具可能具有侵入性且资源消耗大。因此，我们对野生动物结核病生物学的了解仅限于少数经过充分研究的物种。使用聚合酶链反应（PCR）检测粪便样本是一种非侵入性方法，已用于检测獾体内牛分枝杆菌的排出情况，但其在野生动物结核病监测中的更广泛用途尚不清楚。我们将临床症状的观察数据与对388份粪便样本的PCR检测相结合，以描述2000年至2018年间66只野生狐獴（狐獴属）在社会接触苏氏分枝杆菌后结核病进展的纵向动态。我们的具体目标是：1）测试狐獴粪便样本是否可用于监测结核病；2）描述三种感染状态（PCR阴性暴露、PCR阳性无症状和有临床症状的PCR阳性）之间的结核病进展情况；3）估计结核病易感性的个体差异，此处定义为结核病暴露与检测之间的时间，以及结核病检测后的存活情况。我们发现，狐獴出现临床症状后结核病检测概率为13%（95%置信区间3-46%）。然而，通过对每个样本进行10次PCR重复的适应性检测方案，我们在59%的狐獴出现临床症状之前检测到了隐匿性结核病感染。狐獴在初次接触后约14个月PCR呈阳性，在PCR呈阳性后约1年出现临床症状，并在出现临床症状后5个月内死亡。疾病进展的个体差异很大，狐獴在接触后立即至3.4年后出现临床症状。总体而言，我们的研究为野生动物结核病进展提供了新的见解，并可能有助于指导针对结核病易感野生动物种群的适应性管理策略。
