Kay Emily, Young Melanie J, Muller Chris, Howe Laryssa, Roe Wendi, Gartrell Brett D
Wildbase, Tāwharau Ora, School of Veterinary Science, Massey University, Private Bag 11222, Palmerston North, 4410, New Zealand.
Department of Zoology, University of Otago, PO Box 56 Dunedin 9054, New Zealand.
J Wildl Dis. 2022 Oct 1;58(4):836-846. doi: 10.7589/JWD-D-21-00146.
Coccidia infections in wild birds rarely cause clinical signs; however, disease and mortality can occur with predisposing environmental and host conditions. The Yellow-eyed Penguin (Megadyptes antipodes) is an endangered species endemic to New Zealand that has seen significant ongoing population decline. The aim of this study was to examine the host-pathogen dynamics of coccidian parasites in two wild populations of Yellow-eyed Penguin: the mainland (South Island) population and the sub-Antarctic (Enderby Island) population. There was weak evidence for a difference in the prevalence of the Eimeria sp. in birds from Enderby Island (76.6%; 36/47; 95% confidence interval [CI] 62.78-86.4%) and the South Island of New Zealand (58.54%; 24/41; 95% CI 43.37-72.24%). The mean pathogen load in penguins on Enderby Island was 9,723 oocysts/g of feces (SE=5831 oocysts/g) and from the South Island of New Zealand was 1,050 oocysts/g (SE=398 oocysts/g). No evidence of an association was found between pathogen load and body weight in either study population. The morphology of the sporulated coccidial oocysts was consistent with a novel species of Eimeria. There was statistically significant variation between the oocysts collected from the two sites in all measurements apart from the oocyst wall thickness. However, the standard technique of assessing linear regressions of the length and width of oocysts from both sampling sites was 0.80, and therefore above the standard R2>0.5 used to indicate variation within a single population of oocysts, suggesting that only a single species of Eimeria was present at both sampling locations. The prevalence and pathogen load of Eimeria sp. was substantially higher than previous reports of coccidial oocysts in Yellow-eyed Penguins and free-living Sphenisciformes globally. This host-parasite relationship deserves further investigation, as the impact of this novel organism on the population remains unclear.
野生鸟类中的球虫感染很少引起临床症状；然而，在易感的环境和宿主条件下，可能会出现疾病和死亡情况。黄眼企鹅（Megadyptes antipodes）是新西兰特有的濒危物种，其种群数量一直在持续大幅下降。本研究的目的是研究黄眼企鹅两个野生种群（大陆[南岛]种群和亚南极[恩德比岛]种群）中球虫寄生虫的宿主-病原体动态。关于来自恩德比岛的鸟类（76.6%；36/47；95%置信区间[CI]62.78 - 86.4%）和新西兰南岛的鸟类（58.54%；24/41；95%CI 43.37 - 72.24%）中艾美耳球虫属的患病率差异，证据不足。恩德比岛企鹅的平均病原体负荷为每克粪便9723个卵囊（标准误 = 5831个卵囊/克），新西兰南岛企鹅的平均病原体负荷为每克粪便1050个卵囊（标准误 = 398个卵囊/克）。在任何一个研究种群中，均未发现病原体负荷与体重之间存在关联的证据。孢子化球虫卵囊的形态与一种新的艾美耳球虫物种一致。除卵囊壁厚度外，在所有测量中，从两个地点收集的卵囊之间存在统计学上的显著差异。然而，评估来自两个采样地点的卵囊长度和宽度线性回归的标准技术为0.80，因此高于用于表明单个卵囊种群内变异的标准R2>0.5，这表明在两个采样地点仅存在一种艾美耳球虫。艾美耳球虫属的患病率和病原体负荷显著高于此前全球范围内关于黄眼企鹅和自由生活的企鹅目动物中球虫卵囊的报道。由于这种新生物体对种群的影响尚不清楚，这种宿主-寄生虫关系值得进一步研究。
