Department of Biology, Stanford University, Stanford, CA, USA.
Earth Research Institute, University of California, Santa Barbara, CA, USA.
Glob Chang Biol. 2021 Feb;27(4):738-754. doi: 10.1111/gcb.15435. Epub 2020 Nov 22.
Lyme disease is the most common vector-borne disease in temperate zones and a growing public health threat in the United States (US). The life cycles of the tick vectors and spirochete pathogen are highly sensitive to climate, but determining the impact of climate change on Lyme disease burden has been challenging due to the complex ecology of the disease and the presence of multiple, interacting drivers of transmission. Here we incorporated 18 years of annual, county-level Lyme disease case data in a panel data statistical model to investigate prior effects of climate variation on disease incidence while controlling for other putative drivers. We then used these climate-disease relationships to project Lyme disease cases using CMIP5 global climate models and two potential climate scenarios (RCP4.5 and RCP8.5). We find that interannual variation in Lyme disease incidence is associated with climate variation in all US regions encompassing the range of the primary vector species. In all regions, the climate predictors explained less of the variation in Lyme disease incidence than unobserved county-level heterogeneity, but the strongest climate-disease association detected was between warming annual temperatures and increasing incidence in the Northeast. Lyme disease projections indicate that cases in the Northeast will increase significantly by 2050 (23,619 ± 21,607 additional cases), but only under RCP8.5, and with large uncertainty around this projected increase. Significant case changes are not projected for any other region under either climate scenario. The results demonstrate a regionally variable and nuanced relationship between climate change and Lyme disease, indicating possible nonlinear responses of vector ticks and transmission dynamics to projected climate change. Moreover, our results highlight the need for improved preparedness and public health interventions in endemic regions to minimize the impact of further climate change-induced increases in Lyme disease burden.
莱姆病是温带地区最常见的虫媒传染病，也是美国日益严重的公共卫生威胁。蜱虫媒介和螺旋体病原体的生命周期对气候高度敏感，但由于疾病的复杂生态系统和多种相互作用的传播驱动因素的存在，确定气候变化对莱姆病负担的影响一直具有挑战性。在这里，我们将 18 年来每年的县级莱姆病病例数据纳入面板数据统计模型，在控制其他假定的传播驱动因素的同时，研究气候变异对疾病发病率的先前影响。然后，我们使用这些气候-疾病关系，利用 CMIP5 全球气候模型和两种潜在的气候情景（RCP4.5 和 RCP8.5）来预测莱姆病病例。我们发现，所有包含主要媒介物种范围的美国地区的莱姆病发病率的年际变化与气候变异有关。在所有地区，气候预测因素解释的莱姆病发病率变化都小于未观察到的县级异质性，但检测到的最强的气候-疾病关联是与东北变暖的年平均温度和发病率增加之间的关联。莱姆病预测表明，到 2050 年，东北部的病例将显著增加（增加 23619±21607 例），但仅在 RCP8.5 下，而且对这一预测增加的不确定性很大。在任何其他气候情景下，都没有预测到任何其他地区的病例会发生重大变化。这些结果表明气候变化与莱姆病之间存在区域多变且细微的关系，表明对预测气候变化的向量蜱虫和传播动态可能存在非线性反应。此外，我们的研究结果强调了在流行地区加强准备和公共卫生干预的必要性，以尽量减少进一步气候变化引起的莱姆病负担增加的影响。
