Ogden N H, Maarouf A, Barker I K, Bigras-Poulin M, Lindsay L R, Morshed M G, O'callaghan C J, Ramay F, Waltner-Toews D, Charron D F
Groupe de Recherche en Epidémiologie des Zoonoses et Santé Publique, Faculté de Médecine Vétérinaire, Université de Montréal, Que., Canada.
Int J Parasitol. 2006 Jan;36(1):63-70. doi: 10.1016/j.ijpara.2005.08.016. Epub 2005 Oct 5.
We used an Ixodes scapularis population model to investigate potential northward spread of the tick associated with climate change. Annual degree-days >0 degrees C limits for I. scapularis establishment, obtained from tick population model simulations, were mapped using temperatures projected for the 2020s, 2050s and 2080s by two Global Climate Models (the Canadian CGCM2 and the UK HadCM3) for two greenhouse gas emission scenario enforcings 'A2'and 'B2' of the Intergovernmental Panel on Climate Change. Under scenario 'A2' using either climate model, the theoretical range for I. scapularis establishment moved northwards by approximately 200 km by the 2020s and 1000 km by the 2080s. Reductions in emissions (scenario 'B2') had little effect on projected range expansion up to the 2050s, but the range expansion projected to occur between the 2050s and 2080s was less than that under scenario 'A2'. When the tick population model was driven by projected annual temperature cycles (obtained using CGCM2 under scenario 'A2'), tick abundance almost doubled by the 2020s at the current northern limit of I. scapularis, suggesting that the threshold numbers of immigrating ticks needed to establish new populations will fall during the coming decades. The projected degrees of theoretical range expansion and increased tick survival by the 2020s, suggest that actual range expansion of I. scapularis may be detectable within the next two decades. Seasonal tick activity under climate change scenarios was consistent with maintenance of endemic cycles of the Lyme disease agent in newly established tick populations. The geographic range of I. scapularis-borne zoonoses may, therefore, expand significantly northwards as a consequence of climate change this century.
我们使用肩突硬蜱种群模型来研究该蜱虫与气候变化相关的潜在向北扩散情况。通过蜱虫种群模型模拟得出肩突硬蜱生存的年度日>0摄氏度限值，并利用两个全球气候模型（加拿大的CGCM2和英国的HadCM3）针对政府间气候变化专门委员会的两种温室气体排放情景“A2”和“B2”预测的2020年代、2050年代和2080年代的温度进行绘制。在“A2”情景下，无论使用哪种气候模型，到2020年代肩突硬蜱生存的理论范围向北移动了约200公里，到2080年代向北移动了1000公里。排放量减少（“B2”情景）在2050年代之前对预测的范围扩张影响不大，但预计在2050年代至2080年代之间发生的范围扩张小于“A2”情景。当蜱虫种群模型由预测的年温度周期驱动时（在“A2”情景下使用CGCM2获得），到2020年代，在肩突硬蜱当前的北界处蜱虫数量几乎翻倍，这表明在未来几十年内建立新种群所需的迁入蜱虫阈值数量将会下降。预计到2020年代理论范围扩张的程度以及蜱虫存活率的提高，表明在未来二十年内可能会检测到肩突硬蜱实际范围的扩张。气候变化情景下蜱虫的季节性活动与新建立的蜱虫种群中莱姆病病原体地方病循环的维持相一致。因此，由于本世纪的气候变化，肩突硬蜱传播的人畜共患病的地理范围可能会大幅向北扩展。
