Department of Ecology, Montana State University, 310 Lewis Hall, S 11th Avenue, PO Box 173460, Bozeman, Montana 59717, USA.
US Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska 99508, USA.
J Wildl Dis. 2021 Oct 1;57(4):799-807. doi: 10.7589/JWD-D-20-00159.
Haemosporidian parasites may impact avian health and are subject to shifts in distribution and abundance with changing ecologic conditions. Therefore, understanding variation in parasite prevalence is important for evaluating biologically meaningful changes in infection patterns and associated population level impacts. Previous research in western Alaska, US, indicated a possible increase in Leucocytozoon spp. infection between Emperor Geese (Anser canagicus) sampled in 1996 (<1%, n=134) and during 2011-12 (19.9%, 95% confidence interval [CI]: 3.0-36.8%, n=77); however, different detection methods were used for these estimates. Prior research in this same region identified a lack of Leucocytozoon spp. parasites (0%, n=117) in sympatrically breeding Cackling Geese (Branta hutchinsii minima) in 2011. We molecularly screened blood samples collected from sympatrically breeding Emperor and Cackling Geese in western Alaska during additional breeding seasons to better assess temporal and species-specific variation in the prevalence of blood parasites. We found similar prevalence estimates for Leucocytozoon spp. parasites in Emperor Goose blood samples collected in 1998 and 2014, suggesting consistent infection of Emperor Geese with blood parasites at these time points. Using samples from sympatric geese sampled during 2014, we found evidence for a higher incidence of parasites among Emperor Geese (20.3%, 95% CI: 11.8-32.7%) compared to Cackling Geese (3.6%, 95% CI: 1.1-11.0%), reinforcing the previous finding of species-specific differences in infection. Furthermore, we detected Leucocytozoon, Haemoproteus, and Plasmodium spp. blood parasites in unflighted goslings of both species, supporting the possible transmission of these parasites at western Alaska breeding grounds. Our results help to clarify that prevalence of Leucocytozoon spp. parasites have probably remained consistent among Emperor Geese breeding in western Alaska since the late 1990s and that this species may disproportionally harbor Leucocytozoon spp. compared to sympatrically breeding Cackling Geese.
血孢子虫寄生虫可能会影响鸟类的健康，并随着生态条件的变化而改变其分布和丰度。因此，了解寄生虫流行率的变化对于评估感染模式的生物学意义上的变化以及相关的种群水平影响非常重要。美国阿拉斯加西部的先前研究表明，帝王鹅（Anser canagicus）在 1996 年（<1%，n=134）和 2011-12 年（19.9%，95%置信区间[CI]：3.0-36.8%，n=77）之间的白细胞孢子虫属（Leucocytozoon spp.）感染可能增加；然而，这些估计值使用了不同的检测方法。在同一地区的先前研究中，在 2011 年共生繁殖的加拿大黑雁（Branta hutchinsii minima）中发现缺乏白细胞孢子虫属寄生虫（0%，n=117）。我们对在阿拉斯加西部共生繁殖的帝王和加拿大黑雁进行了血液样本的分子筛选，以更好地评估血液寄生虫在时间和物种特异性方面的流行率变化。我们发现 1998 年和 2014 年采集的帝王鹅血液样本中白细胞孢子虫属寄生虫的流行率估计值相似，这表明在这些时间点帝王鹅一直受到血液寄生虫的感染。使用 2014 年共生鹅采集的样本，我们发现帝王鹅的寄生虫发病率高于加拿大黑雁（20.3%，95%CI：11.8-32.7%），而加拿大黑雁的寄生虫发病率（3.6%，95%CI：1.1-11.0%），这进一步证实了感染物种特异性差异的先前发现。此外，我们在两种物种的未飞行幼鹅中检测到白细胞孢子虫、血疟原虫和疟原虫属寄生虫，这支持了在阿拉斯加西部繁殖地传播这些寄生虫的可能性。我们的研究结果有助于澄清，自 20 世纪 90 年代末以来，帝王鹅在阿拉斯加西部繁殖的白细胞孢子虫属寄生虫的流行率可能保持稳定，与共生繁殖的加拿大黑雁相比，该物种可能不成比例地携带白细胞孢子虫属寄生虫。
