Nature Research Centre, Akademijos 2, 08412, Vilnius, Lithuania.
Malar J. 2022 Mar 24;21(1):105. doi: 10.1186/s12936-022-04116-7.
Malaria is a health problem not only in human and veterinary medicine, but also in wildlife. Several theoretical studies have suggested that avian malaria transmission might be increasing in Europe. However, there are few direct empirical observations. Research on the distribution of avian haemosporidian parasites was initiated around the Curonian Lagoon, Europe in 1976 and continues since. This has provided an opportunity to compare the prevalence and diversity of avian malaria parasites (genus Plasmodium) and related haemosporidians (genera Haemoproteus and Leucocytozoon) in the same bird species using similar methodology but examined in two groups 40 years apart. This study aimed to describe and discuss the available data on this subject.
Prevalence and diversity of haemosporidians was compared in two passeriform bird groups, which consisted of the same species that were sampled on the coast of the Curonian Lagoon (Russia, Lithuania) during the same season (September) in 1978-1983 (bird Group 1) and 2020 (bird Group 2). Blood films of the European robin, Coal tit, Great tit, Eurasian wren, and Eurasian jay were screened by microscopic examination. Parasites were identified using morphological characters of blood stages. PCR-based methods were applied to determine genetic lineages of the parasites found in birds of Group 2.
No difference was discernible in the prevalence or diversity of haemosporidian parasites belonging to Haemoproteus, Leucocytozoon, Plasmodium (Haemamoeba) and Plasmodium (Novyella) between birds of Groups 1 and 2. This indicates a similar rate of transmission and relatively stable epidemiological situation in regard of these infections during the past 40 years. The prevalence of only one malaria parasite species, Plasmodium (Giovannolaia) circumflexum, increased remarkably, but only in Coal tit, Great tit, and Eurasian wren, with no significant prevalence change in European robin and Eurasian jay.
Plasmodium circumflexum is spreading and seems to be a new invasive avian malaria pathogen in countries with cold climates. The exceptionally high prevalence of P. circumflexum in birds breeding in relatively close-nests suggests an important role of the nesting biology related to bird-vector interaction in this pathogen transmission. The epidemiological situation seems to be relatively stable in regard of other studied avian hosts and haemosporidian parasites in northern Europe.
疟疾不仅是人类和兽医医学中的一个健康问题，也是野生动物中的一个健康问题。一些理论研究表明，在欧洲，鸟类疟疾的传播可能正在增加。然而，直接的实证观察却很少。1976 年，在欧洲的库尔斯沙嘴泻湖周围开始了对鸟类血孢子虫寄生虫分布的研究，并一直持续到现在。这为比较同一鸟类物种中使用相似方法但在 40 年时间内检查的两种鸟类群中，鸟类疟原虫（属 Plasmodium）和相关血孢子虫（属 Haemoproteus 和 Leucocytozoon）的流行率和多样性提供了机会。本研究旨在描述和讨论这方面的现有数据。
对两个雀形目鸟类群中的血孢子虫流行率和多样性进行了比较，这两个鸟类群由在同一季节（9 月）在库尔斯沙嘴泻湖（俄罗斯、立陶宛）的海岸上采集的相同物种组成，分别为 1978-1983 年（鸟类群 1）和 2020 年（鸟类群 2）。通过显微镜检查筛选欧洲知更鸟、煤山雀、大山雀、欧亚鹪鹩和欧亚松鸦的血涂片。寄生虫的鉴定采用血期形态特征。应用基于 PCR 的方法确定了鸟类群 2 中发现的寄生虫的遗传谱系。
鸟类群 1 和 2 中的血孢子虫寄生虫属 Haemoproteus、Leucocytozoon、Plasmodium（Haemamoeba）和 Plasmodium（Novyella）的流行率或多样性没有差异。这表明在过去的 40 年中，这些感染的传播速度和相对稳定的流行病学情况相似。只有一种疟原虫物种，即 Plasmodium（Giovannolaia）circumflexum 的流行率显著增加，但仅在煤山雀、大山雀和欧亚鹪鹩中增加，而欧洲知更鸟和欧亚松鸦的流行率没有显著变化。
Plasmodium circumflexum 正在传播，似乎是寒冷气候国家新出现的入侵性鸟类疟原虫病原体。在相对紧密巢穴中繁殖的鸟类中 Plasmodium circumflexum 的异常高流行率表明，与鸟类-媒介相互作用有关的筑巢生物学在这种病原体传播中起着重要作用。在北欧，其他研究的鸟类宿主和血孢子虫寄生虫的流行病学情况似乎相对稳定。
