Ansil B R, Viswanathan Ashwin, Ramachandran Vivek, Yeshwanth H M, Sanyal Avirup, Ramakrishnan Uma
National Centre for Biological Sciences Tata Institute of Fundamental Research Bangalore Karnataka India.
Manipal Academy of Higher Education Manipal Karnataka India.
Ecol Evol. 2025 Apr 2;15(4):e71085. doi: 10.1002/ece3.71085. eCollection 2025 Apr.
Bacterial infections account for a large proportion of zoonoses. Our current understanding of zoonotic spillover, however, is largely based on studies from viral systems. Small mammals such as rodents and their ectoparasites present a unique system for studying several bacterial pathogens and mapping their spillover pathways. Using spp. (a Gram-negative bacteria) as a model system within a rainforest human-use landscape, we investigated (1) ecological correlates of prevalence in small mammal hosts and (2) evolutionary relationships between spp. and various hosts and ectoparasites to gain insight into pathogen movement pathways within ecological communities. We detected in five out of eight small mammal species and in 86 (40.56%) out of 212 individuals, but prevalence varied widely among species (0%-75.8%). Seven of the ten ectoparasite species found on these small mammals were positive for . Interestingly, while genotypes (15) in small mammals were host-specific, ectoparasites had nonspecific associations, suggesting the possibility for vector-mediated cross-species transmission. We also found that prevalence in hosts was positively correlated with their aggregated ectoparasite loads, further emphasizing the crucial role that ectoparasites may play in these transmission pathways. Our cophylogenetic analysis and ancestral trait (host) reconstruction revealed incongruence between small mammal and phylogenies, indicating historic host shifts and validating the potential for contemporary spillover events. We found that small mammal hosts in this fragmented landscape often move across habitat boundaries, creating a transmission pathway (via shared ectoparasites) to novel hosts, which may include synanthropic species like . Our results highlight the necessity to disentangle the complex relationship among hosts, ectoparasites, and bacterial pathogens to understand the implications of undetected spillover events.
细菌感染在人畜共患病中占很大比例。然而，我们目前对人畜共患病毒溢出的理解在很大程度上基于病毒系统的研究。啮齿动物等小型哺乳动物及其体外寄生虫为研究几种细菌病原体并绘制其溢出途径提供了一个独特的系统。我们以热带雨林人类利用景观中的[具体细菌名称]（一种革兰氏阴性菌）为模型系统，研究了（1）小型哺乳动物宿主中[具体细菌名称]流行率的生态相关性，以及（2）[具体细菌名称]与各种宿主和体外寄生虫之间的进化关系，以深入了解生态群落内病原体的传播途径。我们在8种小型哺乳动物中的5种以及212只个体中的86只（40.56%）中检测到了[具体细菌名称]，但不同物种之间的流行率差异很大（0%-75.8%）。在这些小型哺乳动物身上发现的10种体外寄生虫物种中有7种对[具体细菌名称]呈阳性。有趣的是，虽然小型哺乳动物中的[具体细菌名称]基因型（15种）具有宿主特异性，但体外寄生虫具有非特异性关联，这表明存在媒介介导的跨物种传播的可能性。我们还发现，宿主中[具体细菌名称]的流行率与其体外寄生虫聚集负荷呈正相关，进一步强调了体外寄生虫在这些传播途径中可能发挥的关键作用。我们的共系统发育分析和祖先特征（宿主）重建揭示了小型哺乳动物和[具体细菌名称]系统发育之间的不一致，表明历史上的宿主转移，并验证了当代溢出事件的可能性。我们发现，在这个破碎化景观中的小型哺乳动物宿主经常跨越栖息地边界，为新宿主创造了一条传播途径（通过共享的体外寄生虫），新宿主可能包括像[具体物种名称]这样的伴人物种。我们的结果强调了理清宿主、体外寄生虫和细菌病原体之间复杂关系以了解未检测到的溢出事件影响的必要性。
