Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia.
Endeavour Veterinary Ecology Pty Ltd, 1695 Pumicestone Rd, Toorbul, QLD, 4510, Australia.
Sci Rep. 2021 Feb 24;11(1):4419. doi: 10.1038/s41598-021-83919-1.
Koala populations in many areas of Australia have declined sharply in response to habitat loss, disease and the effects of climate change. Koalas may face further morbidity from endemic mosquito-borne viruses, but the impact of such viruses is currently unknown. Few seroprevalence studies in the wild exist and little is known of the determinants of exposure. Here, we exploited a large, spatially and temporally explicit koala survey to define the intensity of Ross River Virus (RRV) exposure in koalas residing in urban coastal environments in southeast Queensland, Australia. We demonstrate that RRV exposure in koalas is much higher (> 80%) than reported in other sero-surveys and that exposure is uniform across the urban coastal landscape. Uniformity in exposure is related to the presence of the major RRV mosquito vector, Culex annulirostris, and similarities in animal movement, tree use, and age-dependent increases in exposure risk. Elevated exposure ultimately appears to result from the confinement of remaining coastal koala habitat to the edges of permanent wetlands unsuitable for urban development and which produce large numbers of competent mosquito vectors. The results further illustrate that koalas and other RRV-susceptible vertebrates may serve as useful sentinels of human urban exposure in endemic areas.
考拉在澳大利亚许多地区的数量急剧下降，这是对栖息地丧失、疾病和气候变化影响的反应。考拉可能会因地方性蚊子传播的病毒而面临更高的发病率，但目前还不清楚这些病毒的影响。野外存在的血清阳性率研究很少，对暴露的决定因素知之甚少。在这里，我们利用一项大规模的、具有空间和时间明确性的考拉调查，来确定澳大利亚昆士兰州东南部城市沿海环境中居住的考拉感染罗斯河病毒（RRV）的强度。我们证明，考拉感染 RRV 的强度远远高于其他血清学调查所报告的强度，而且在城市沿海景观中，暴露的强度是均匀的。暴露的均匀性与主要的 RRV 蚊子传播媒介库蚊有关，以及动物运动、树木使用和年龄相关的暴露风险增加的相似性。暴露水平的升高最终似乎是由于剩余的沿海考拉栖息地被限制在永久性湿地的边缘，这些湿地不适合城市发展，而且会产生大量有能力的蚊子媒介。研究结果进一步表明，考拉和其他易感染 RRV 的脊椎动物可能成为地方性地区人类城市暴露的有用哨兵。
