Identifying key reservoirs for zoonoses is crucial for understanding variation in incidence. Plague re-emerged in Mahajanga, Madagascar in the 1990s but there has been no confirmed case since 1999. Here we combine ecological and genetic data, from during and after the epidemics, with experimental infections to examine the role of the shrew Suncus murinus in the plague epidemiological cycle. The predominance of S. murinus captures during the epidemics, their carriage of the flea vector and their infection with Yersinia pestis suggest they played an important role in the maintenance and transmission of plague. S. murinus exhibit a high but variable resistance to experimental Y. pestis infections, providing evidence of its ability to act as a maintenance host. Genetic analyses of the strains isolated from various hosts were consistent with two partially-linked transmission cycles, with plague persisting within the S. murinus population, occasionally spilling over into the rat and human populations. The recent isolation from a rat in Mahajanga of a Y. pestis strain genetically close to shrew strains obtained during the epidemics reinforces this hypothesis and suggests circulation of plague continues. The observed decline in S. murinus and Xenopsylla cheopis since the epidemics appears to have decreased the frequency of spillover events to the more susceptible rats, which act as a source of infection for humans. Although this may explain the lack of confirmed human cases in recent years, the current circulation of plague within the city highlights the continuing health threat.

识别人畜共患病的关键水库对于了解发病率的变化至关重要。鼠疫于1990年代在马达加斯加的Mahajanga再次出现，但自1999年以来没有确诊病例。在这里，我们结合了流行期间和之后的生态和遗传数据，以及实验性感染，研究了sh在印度洋Sun中的作用。鼠疫流行病学周期。S的优势。鼱疫情期间捕捉，他们的跳蚤矢量运输及其与感染鼠疫建议他们在瘟疫的维护和传播发挥了重要作用。小号。粘液鼠对实验动物表现出很高的抵抗力ÿ。瘟病感染，提供了其作为维持宿主的能力的证据。从不同宿主分离的菌株的遗传分析与两个部分连锁的传播周期一致，鼠疫在S内持续存在。鼠种群，偶尔会扩散到老鼠和人类种群中。从在马任加的大鼠近期隔离ÿ。菌菌株基因靠近流行病期间获得鼩菌株强化了这一假说，并建议鼠疫的循环继续进行。观察到的S下降。鼠和Xenopsylla豹由于这种流行病似乎减少了向易感大鼠传播外溢事件的频率，易感大鼠是人类的传染源。尽管这可以解释近年来缺乏确诊的人类病例，但该市内当前的鼠疫流行凸显出持续的健康威胁。