ABSTRACT

Arctic fox (Vulpes lagopus) and its tundra habitat are a unique system for the study of rabies virus epidemics. Contrary to theoretical calculations reporting a critical density (K_T) of approximately 1 fox/km² for rabies endemicity, arctic rabies persists at densities below this. The calculation of K_T = 1 fox/km² assumes uniform fox density across the landscape and unrestricted mixing between susceptible and infected foxes. We hypothesize that spatial heterogeneity arising from resource distribution or social structure may result in regions where rabies is endemic, even though average fox densities at the regional or landscape-level are below K_T. To expand upon the limited body of research surrounding arctic rabies persistence, we examine arctic rabies via a two-patch structure. We find that arctic rabies can persist in heterogeneous landscapes where the mean carrying capacity is below the threshold carrying capacity required for endemicity in homogeneous landscapes. Rabies endemicity in low-carrying capacity regions within heterogeneous landscapes is further facilitated by high transmission rates, potentially due to non-breeding foxes (i.e. floaters), and when between-patch movement is restricted to latent and infected foxes. Our results suggest that rabies may persist in heterogeneous landscapes when the mean carrying capacity is as low as 0.25 foxes/km².

摘要

北极狐（Vulpes lagopus）及其苔原栖息地是研究狂犬病病毒流行的独特系统。与报告狂犬病流行的临界密度 (K _T ) 约为 1 只狐狸/km ^{2 的}理论计算相反，北极狂犬病在低于此密度的情况下持续存在。K _T  = 1 fox/km ^{2 的计算}假设整个景观中的狐狸密度均匀，易感狐狸和受感染狐狸之间不受限制地混合。我们假设资源分布或社会结构引起的空间异质性可能导致狂犬病流行的地区，即使区域或景观水平的平均狐狸密度低于 K _T. 为了扩展围绕北极狂犬病持续性的有限研究，我们通过两片结构检查北极狂犬病。我们发现北极狂犬病可以在异质景观中持续存在，其中平均承载能力低于在同质景观中流行所需的阈值承载能力。高传播率进一步促进了异质景观内低携带能力地区的狂犬病流行，这可能是由于非繁殖狐狸（即飞蚊症），以及当斑块之间的移动仅限于潜伏和受感染的狐狸时。我们的结果表明，当平均携带能力低至 0.25 只狐狸/km ²时，狂犬病可能会在异质景观中持续存在。