When Angela Theodosopoulos began studying Colorado's Mountain and Black-capped Chickadees four years ago, her original goal was to research hybridization among the species and the various parasites they each co-evolved with. But when the PhD candidate at the 博彩平台推荐 began analyzing the birds' blood, she made a worrisome discovery: Some of the chickadees were infected with a strain of introduced avian malaria.
根据… 本月发表的报告 in 生物学快报, Theodosopoulos' finding is the first record of this particular strain in a non-migratory bird species in North America. The parasite was found in two Mountain Chickadees and a single Black-capped Chickadee, 但由于感染人数少，Theodosopoulos, 论文的第一作者, believe that another avian species might be the main host. While the strain has the potential to be damaging to bird populations, Theodosopoulos强调需要更多的研究.
“在这一点上，我绝对不会恐慌，”她说. “But it is important to think about it and to understand it, 因为它是一种侵入性很强的寄生虫, 它会导致疾病, and it has been associated with population declines in other places. We just don't know if that's going to be what happens here.”
禽疟是由一种寄生虫引起的 在鸟类的红细胞中繁殖 并通过蚊子传播. Though some cases of avian malaria are mild or asymptomatic, infected birds can experience a loss of red blood cells, 嗜睡, 寿命缩短, 或者在极端情况下, 抽搐或死亡.
在博尔德发现的菌株被称为SGS1, named for the species it was first identified in: a Sudan Golden Sparrow in 2002. 一般来说, genetic variation in parasites leads to different strains of the disease, which tend to infect species in different geographic areas. But when a strain reaches birds that haven't encountered it before and are not adapted to fight it, “它会对人类造成很大的伤害,斯塔凡·本施说, professor of animal ecology at Lund University in Sweden and co-author on the paper. 研究ers can’t say yet how North American birds will respond to SGS1, 但在伦敦, SGS1已经 与家麻雀数量减少有关.
The fact that the parasite has infected non-migratory chickadees is concerning because it's “a sign that it is already spreading,西奥多索普罗斯说. A migratory bird can be infected anywhere along its journey, but the chickadees had to have contracted the disease locally. 直到现在, the only recorded North American birds with SGS1 were captive birds in New York and one wild, 加拿大迁徙的树燕. Theodosopoulos speculates mosquitoes may have spread the disease from infected birds in zoos, which could have contracted it before they were imported.
“他们中的许多人在圈养中康复了，”本施说. “But in the wild, such a bird is very easy prey for a raptor.”
下一个, the researchers want to find out if SGS1 really is more prevalent in another local species—and which one. 他们认为可能是家麻雀, given the high infection rate of that species in Europe and their large populations in urban areas. Theodosopoulos hopes to discover if and when SGS1 infected House Sparrows in Colorado and, 之后, 了解它可能到达的其他物种.
为此，她与Dr. Garth Spellman, curator of ornithology at the Denver Museum of Nature & 科学. Spellman has a collection of tissue samples from House Sparrows from the Denver metropolitan area dating back 10 years. 顺便说一下, a paper published approximately a decade ago found no instances of SGS1 in House Sparrows in the Colorado Front Range, 包括丹佛和博尔德在内的山区. So, Spellman and Theodosopoulos believe that if SGS1 has infected House Sparrows, 在过去的10年里，它很可能就是这样做的.
“博彩平台推荐可以看20个, 30 birds every year for the last decade to see if we can find SGS1,斯佩尔曼说. “If so, we might be able to chronicle the year that it arrived in the Front Range.“基于这些样本中SGS1的患病率, they could also estimate how common it is in House Sparrows today.
This future research will be crucial to understanding the extent of risk to North American birds. If SGS1 is found at a high rate in Colorado’s House Sparrows, Spellman believes that would be a sign that House Sparrows in metro areas nationwide are infected. 此外, a high presence of SGS1 in urban birds might increase the chances of avian malaria spreading to birds outside cities.
“在丹佛, 这可能特别重要, 因为博彩平台推荐有很多草原物种, 例如, that could be exposed right at that urban-wildland interface,斯佩尔曼说. 了, 74%的草原鸟类正在减少. “If just one of those species is exposed to a novel pathogen, that could have dire consequences.”
For now, it’s a waiting game as scientists gather more information. If, 从理论上讲, 研究人员在该国其他地方发现了SGS1, 如果死鸟的SGS1病毒检测呈阳性, and if the birds that carry SGS1 start having negative health impacts while uninfected individuals don’t, then this strain would be something to really worry about, Theodosopoulos说.
Even if SGS1 winds up not causing any major issues for North American birds, 正如论文所指出的, the appearance of this strain is yet another reminder of the human impact on the environment and the need for diligence in a more globalized world. “We're changing the habitat; we’re moving species around,西奥多索普罗斯说. “This certainly plays a role in the way that parasites and their diseases are able to spread.”
