Overview of the data associated with this study.

Background Plague, a zoonosis caused by Yersinia pestis, is endemic in Madagascar but knowledge on the epidemiological situation in the northern focus remains unclear. The aim of this study was to investigate the circulation of Y. pestis in terrestrial small mammals in north eastern Madagascar, where suspected plague outbreaks have been reported. Methods Sampling of terrestrial small mammals and their fleas was carried out in 22 trapping sites within 9 localities of the two sectors (1 and 3) of Makira Natural Park (MNP) and surroundings, from 2020 to 2022. Yersinia pestis was investigated in terrestrial small mammal spleen samples and their fleas using bacteriological, serological and molecular methods. Results A total of 614 terrestrial small mammals composed of eight species and 1,754 individual fleas were collected following 4,880 trap-nights. The black rat (Rattus rattus) represented the majority (87.8%) of the small mammal species caught. Flea infestation rate was higher in sector 3 compared to sector 1. In sector 3, Xenopsylla brasiliensis, a plague vector, represented 66.4% of fleas identified. Further, one plague seropositive R. rattus individual, captured inside a house, and one Ctenocephalides felis specimen, collected on another R. rattus, was positive on PCR in this sector. Discussion Despite low detection rates, we confirmed the circulation of Y. pestis in our study area (one rat seropositive and one flea PCR positive) and highlight the risk of potential human transmission. Our results also suggest that R. rattus contributes to the maintenance and transmission of plague in MNP, as described for other areas in Madagascar. Further, these findings contribute to documentation of the known geographic distribution of the endemic plague vector S. fonquerniei and X. brasiliensis. Conclusion The confirmation of the circulation of the Y. pestis through serological and molecular diagnostics in small mammals and fleas underscores the urgent need to assess awareness levels of risk factors and symptoms to monitor among local communities and health workers and ensure that trained rapid response teams are prepared to intervene promptly upon suspect case detection. The risk and epidemiology of plague circulation in remote rural areas of Madagascar remains insufficiently studied. Addressing this gap is crucial, as a more comprehensive understanding of the distribution and dynamics of the wild animal hosts, their vectors and host-vector interactions will enhance risk assessment and prevention for plague emergence and improve mitigation and early control of potential outbreaks.背景 鼠疫是由鼠疫耶尔森菌（Yersinia pestis）引起的人畜共患病，在马达加斯加呈地方性流行，但针对其北部疫源地的流行病学现状仍尚不明确。本研究旨在调查马达加斯加东北部陆生小型哺乳动物体内鼠疫耶尔森菌的传播循环情况——该区域曾有疑似鼠疫暴发的报道。 方法 2020年至2022年间，研究人员在马基拉自然保护区（Makira Natural Park, MNP）及其周边的2个片区（片区1与片区3）的9个采样点内的22处诱捕位点开展陆生小型哺乳动物及其体表跳蚤的采样工作。通过细菌学、血清学与分子生物学方法，对陆生小型哺乳动物的脾脏样本及其体表跳蚤进行鼠疫耶尔森菌检测。 结果 本次研究累计开展4880个诱捕夜，共采集到8个物种的614只陆生小型哺乳动物，以及1754只个体跳蚤。捕获的小型哺乳动物中，黑家鼠（Rattus rattus）占比最高，达87.8%。片区3的跳蚤寄生率高于片区1。在片区3中，作为鼠疫媒介的巴西客蚤（Xenopsylla brasiliensis）占已鉴定跳蚤总数的66.4%。此外，该片区内1只捕获于住宅内的血清学阳性黑家鼠，以及1只采自另一只黑家鼠的猫栉首蚤（Ctenocephalides felis）样本，经聚合酶链式反应（PCR）检测呈阳性。 讨论 尽管检测阳性率较低，但本研究证实了研究区域内存在鼠疫耶尔森菌的传播循环（1只血清学阳性大鼠与1份PCR阳性跳蚤样本），并凸显了人间潜在传播的风险。本研究结果同时表明，黑家鼠在马基拉自然保护区的鼠疫维持与传播中发挥作用，这与马达加斯加其他区域的相关研究结论一致。此外，本研究结果还为地方性鼠疫媒介S. fonquerniei与巴西客蚤的已知地理分布记录提供了补充数据。 结论 通过血清学与分子生物学检测手段，证实小型哺乳动物及跳蚤体内存在鼠疫耶尔森菌的传播循环，这凸显了一项迫切需求：需评估当地社区与医护人员对鼠疫风险因素与临床症状的认知水平，同时需组建经过培训的快速响应队伍，以便在疑似病例被发现时能够迅速开展干预。目前针对马达加斯加偏远农村地区的鼠疫传播风险与流行病学情况的研究仍显不足。填补这一研究空白至关重要，因为全面了解野生宿主动物、其传播媒介以及宿主-媒介互作的分布与动态，将有助于提升鼠疫暴发的风险评估与预防能力，并改善潜在暴发的缓解与早期防控工作。