Rasoamalala Fanohinjanaharinirina, Ramasindrazana Beza, Parany Mamionah J, Rahajandraibe Soloandry, Randriantseheno Lovasoa, Rahelinirina Soanandrasana, Gorgé Olivier, Valade Eric, Harimalala Mireille, Rajerison Minoarisoa, Cauchemez Simon, Brault Antoine
Plague Unit, Institut Pasteur de Madagascar, Antananarivo 101, Madagascar.
Doctoral School Life and Environmental Sciences, University of Antananarivo, Antananarivo 101, Madagascar.
Proc Natl Acad Sci U S A. 2025 Jun 17;122(24):e2502161122. doi: 10.1073/pnas.2502161122. Epub 2025 Jun 12.
Plague continues to pose a public health problem in multiple regions of the world, including Madagascar, where it is characterized by a pronounced seasonal pattern. The drivers of plague seasonality remain poorly understood. Using a deterministic compartmental model, calibrated to rat and flea capture data, serological data collected in active rural foci, and human plague surveillance data, we analyzed the effects of seasonal rat and flea population dynamics on plague transmission. The models that incorporated seasonal fluctuations in rat and flea populations provided better predictive performances than those that did not. We found that a simpler mass-action model also performed well. Driven by these seasonal changes, the effective reproduction number (R) between rats peaks at 1.45 [95% credible interval (CI): 1.41, 1.48] in October and falls to 0.6 (95% CI: 0.57, 0.63) in March. We estimated that 0.5% (95% CI: 0.2%, 0.9%) of rats are infected annually, indicating that plague is not the main driver of rat population changes. Using our model, we evaluated intervention strategies and found that targeting both rats and their fleas at the start of the epidemic season (July-September) was the most effective approach for reducing human plague cases. Such an approach contrasts with the reactive strategy currently employed in Madagascar. Our findings highlight the role of flea and rat populations in plague seasonality and identify strategies that could be deployed in Madagascar to better control plague epidemics.
鼠疫在世界多个地区，包括马达加斯加，仍然是一个公共卫生问题，在马达加斯加，鼠疫具有明显的季节性模式。鼠疫季节性的驱动因素仍知之甚少。我们使用一个确定性的 compartmental 模型，该模型根据大鼠和跳蚤捕获数据、在活跃农村疫源地收集的血清学数据以及人类鼠疫监测数据进行校准，分析了季节性大鼠和跳蚤种群动态对鼠疫传播的影响。纳入大鼠和跳蚤种群季节性波动的模型比未纳入的模型具有更好的预测性能。我们发现一个更简单的质量作用模型也表现良好。在这些季节性变化的驱动下，大鼠之间的有效繁殖数（R）在10月达到峰值1.45[95%可信区间（CI）：1.41，1.48]，在3月降至0.6（95%CI：0.57，0.63）。我们估计每年有0.5%（95%CI：0.2%，0.9%）的大鼠被感染，这表明鼠疫不是大鼠种群变化的主要驱动因素。使用我们的模型，我们评估了干预策略，发现疫情季节开始时（7月至9月）同时针对大鼠及其跳蚤是减少人类鼠疫病例的最有效方法。这种方法与马达加斯加目前采用的应对策略形成对比。我们的研究结果突出了跳蚤和大鼠种群在鼠疫季节性中的作用，并确定了可以在马达加斯加部署的更好控制鼠疫疫情的策略。
