Wait Liana F, Johnson Shylo R, Nelson Kathleen M, Chipman Richard B, Pogmore Frederick E, Dobson Andrew P, Graham Andrea L
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
US Department of Agriculture, Animal and Plant Health Inspection Services, Wildlife Services, National Wildlife Research Center, Fort Collins, CO, 80521, USA.
Int J Parasitol Parasites Wildl. 2023 Apr 27;21:116-128. doi: 10.1016/j.ijppaw.2023.04.011. eCollection 2023 Aug.
Raccoons are host to diverse gastrointestinal parasites, but little is known about the ecology of these parasites in terms of their interactions with each other during coinfections, their interactions with host physiology and environmental factors, and their impact on raccoon health and survival. As a first step, we investigated the patterns of parasite infection and their demographic distribution in an urban-suburban population of raccoons trapped in the summers and autumns of 2018 and 2019. We collected faecal samples, demographic data, morphometric measurements, and blood smears, and used GPS data to classify trapping location by land cover type. Faecal floats were performed to detect and quantify gastrointestinal nematode eggs and coccidia oocysts, and white blood cell differentials were performed on blood smears to characterise white blood cell distributions. Data were analysed cross-sectionally and, where possible, longitudinally, using generalised linear models. Overall, 62.6% of sampled raccoons were infected with gastrointestinal nematodes, and 82.2% were infected with gastrointestinal coccidia. We analysed predictors of infection status and faecal egg count for three different morphotypes of nematode-, strongyle, and capillariid nematodes-and found that infection status and egg count varied with Year, Month, Age class, Land cover, and coinfection status, though the significance of these predictors varied between nematode types. Gastrointestinal coccidia prevalence varied with Year, Month, Age class, strongyle infection status, and capillariid infection status. Coccidia oocyst counts were lower in adults and in October, but higher in females and in raccoons trapped in areas with natural land cover; furthermore, coccidia oocysts were positively associated with capillariid faecal egg counts. We found no evidence that gastrointestinal parasites influenced raccoon body condition or overwinter mortality, and so conclude that raccoons, though harbouring diverse and abundant gastrointestinal parasites, may be relatively tolerant of these parasites.
浣熊是多种胃肠道寄生虫的宿主，但对于这些寄生虫在共感染期间相互之间的相互作用、它们与宿主生理和环境因素的相互作用以及它们对浣熊健康和生存的影响，人们了解甚少。作为第一步，我们调查了2018年和2019年夏秋季节捕获的城市-郊区浣熊种群中寄生虫感染模式及其人口统计学分布。我们收集了粪便样本、人口统计学数据、形态测量数据和血涂片，并使用GPS数据按土地覆盖类型对捕获地点进行分类。进行粪便漂浮检查以检测和量化胃肠道线虫卵和球虫卵囊，并对血涂片进行白细胞分类以表征白细胞分布。使用广义线性模型对数据进行横断面分析，并在可能的情况下进行纵向分析。总体而言，62.6%的采样浣熊感染了胃肠道线虫，82.2%感染了胃肠道球虫。我们分析了线虫、圆线虫和毛细线虫三种不同形态类型的感染状态和粪便虫卵计数的预测因素，发现感染状态和虫卵计数随年份、月份、年龄组、土地覆盖和共感染状态而变化，尽管这些预测因素的显著性在不同线虫类型之间有所不同。胃肠道球虫的患病率随年份、月份、年龄组、圆线虫感染状态和毛细线虫感染状态而变化。球虫卵囊计数在成年浣熊和10月份较低，但在雌性浣熊和捕获于自然土地覆盖区域的浣熊中较高；此外，球虫卵囊与毛细线虫粪便虫卵计数呈正相关。我们没有发现证据表明胃肠道寄生虫会影响浣熊的身体状况或越冬死亡率，因此得出结论，浣熊虽然携带多种且数量丰富的胃肠道寄生虫，但可能对这些寄生虫具有相对耐受性。
