Feldman R A, Freed L A, Cann R L
Department of Genetics and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu 96822, USA.
Mol Ecol. 1995 Dec;4(6):663-73. doi: 10.1111/j.1365-294x.1995.tb00267.x.
The decline of native Hawaiian forest birds since European contact is attributed to factors ranging from habitat destruction to interactions with introduced species. Remaining populations of Hawaiian honeycreepers (Fringillidae: Drepanidinae) are most abundant and diverse in high elevation refuges above the normal range of disease-carrying mosquitoes. Challenge experiments suggest that honeycreepers are highly susceptible to avian malaria (Plasmodium sp.) but resistance exists in some species. In order to detect low levels of malarial infection and quantify prevalence of Plasmodium in high elevation natural populations of Hawaiian birds, a polymerase chain reaction (PCR) based diagnostic test was developed that identifies rRNA genes of Plasmodium in avian blood samples. Quantitative competitive PCR (QC-PCR) experiments indicate that the detection limit of our test is an order of magnitude greater than that reported for human malaria DNA blot tests. Compared with standard histological methods, the PCR test detected a higher prevalence of diseased birds at mid-elevations. Malaria was detected in three species of native birds living in a high elevation wildlife refuge on the island of Hawaii and in four species from Maui. Our results show that avian malaria is more widespread in Hawaiian forests than previously thought, a finding that has important conservation implications for these threatened species.
自欧洲人接触以来，夏威夷本土森林鸟类数量的减少归因于从栖息地破坏到与外来物种相互作用等一系列因素。夏威夷蜜旋木雀（雀科：管舌雀亚科）现存种群在高于携带疾病蚊子正常分布范围的高海拔避难所中最为丰富多样。挑战实验表明，蜜旋木雀对禽疟（疟原虫属）高度易感，但某些物种存在抗性。为了检测夏威夷鸟类高海拔自然种群中低水平的疟疾感染并量化疟原虫的流行情况，开发了一种基于聚合酶链反应（PCR）的诊断测试，用于识别鸟类血液样本中疟原虫的rRNA基因。定量竞争性PCR（QC-PCR）实验表明，我们测试的检测限比人类疟疾DNA印迹测试报告的检测限高一个数量级。与标准组织学方法相比，PCR测试在中海拔地区检测到患病鸟类的患病率更高。在夏威夷岛的一个高海拔野生动物避难所生活的三种本土鸟类以及毛伊岛的四种鸟类中检测到了疟疾。我们的结果表明，禽疟在夏威夷森林中的分布比以前认为的更为广泛，这一发现对这些濒危物种具有重要的保护意义。
