Nature Research Centre, Akademijos 2, 2100, LT-08412, Vilnius, Lithuania.
Malar J. 2022 Sep 19;21(1):269. doi: 10.1186/s12936-022-04235-1.
Haemoproteus is a sister genus to malaria parasites (Plasmodium), which both belong to the order Haemosporida (Apicomplexa). Parasites of both genera are flourishing in birds, however, Haemoproteus species are noticeably less investigated. This is unfortunate because knowledge about close relatives of malaria pathogens is important for better understanding the evolutionary origin and basic biological features of the entire group of haemosporidian infections. Moreover, recent findings show that Haemoproteus species can cause severe damage of various bird organs due to megalomeronts and other exo-erythrocytic stages. These haemosporidians are remarkably diverse, but remain neglected partly due to difficulties in species identification. Hundreds of Haemoproteus genetic lineages have been reported in birds, and numerous new lineages are found each year, but most remain unidentified to the species level. Numerous new Haemoproteus pathogens were described during the past 20 years. However, keys for their identification are absent. Identification of Haemoproteus species remains a difficult task and is an obstacle for better understanding of the distribution and epidemiology of these parasites. This study aimed to develop comprehensive keys for the identification of described avian Haemoproteus species using morphological features of their blood stages (gametocytes).
Type and voucher preparations of avian Haemoproteus species were accessed in museums in Europe, Australia and the USA. Gametocytes of most described species were examined, and these data formed a background for this study. The data also were considered from published articles containing parasite species descriptions. The method of dichotomous keys was applied. The most difficult steps in the keys were accompanied with references to the corresponding parasite pictures.
In all, 201 published articles were included in this review. Morphological diagnostic features of gametocytes of all described Haemoproteus species were analysed and compared. Illustrated keys for identification of these parasite species were developed. Available information about the molecular characterization of Haemoproteus parasites was provided.
This review shows that 177 described species of avian Haemoproteus can be distinguished and identified in blood films using morphological characters of their gametocytes and host cells. These species were incorporated in the keys. Information about possible morphologically cryptic parasites was provided. Molecular markers are available for only 42% of the described Haemoproteus parasites, calling for researchers to fill this gap.
血孢子虫是疟原虫（疟原虫）的姊妹属，两者都属于血孢子虫目（Apicomplexa）。这两个属的寄生虫在鸟类中都很繁盛，然而，血孢子虫的研究明显较少。这很不幸，因为了解疟原虫病原体的近亲对于更好地了解整个血孢子虫感染群的进化起源和基本生物学特征很重要。此外，最近的研究结果表明，由于巨合子和其他红细胞外阶段，血孢子虫物种会对各种鸟类器官造成严重损害。这些血孢子虫种类繁多，但由于物种鉴定困难，部分仍被忽视。据报道，鸟类中有数百种血孢子虫遗传谱系，每年都会发现许多新的谱系，但大多数仍未鉴定到种的水平。在过去的 20 年中，描述了许多新的血孢子虫病原体。但是，缺乏识别它们的关键。血孢子虫物种的鉴定仍然是一项艰巨的任务，也是更好地了解这些寄生虫的分布和流行病学的障碍。本研究旨在使用其血液阶段（配子体）的形态特征，为已描述的禽血孢子虫物种开发全面的鉴定钥匙。
在欧洲、澳大利亚和美国的博物馆中查阅了禽血孢子虫物种的类型和凭证标本。检查了大多数描述物种的配子体，并将这些数据作为本研究的背景。这些数据还来自包含寄生虫物种描述的已发表文章。应用了二项式钥匙法。钥匙中最困难的步骤附有相应寄生虫图片的参考。
总共纳入了本综述的 201 篇已发表文章。分析和比较了所有描述的血孢子虫物种配子体的形态诊断特征，并开发了这些寄生虫物种的鉴定钥匙。提供了有关血孢子虫寄生虫分子特征的信息。
本综述表明，在血片中使用其配子体和宿主细胞的形态特征，可以区分和鉴定 177 种已描述的禽血孢子虫物种。这些物种被纳入了钥匙。提供了有关可能形态隐窝寄生虫的信息。只有 42%的描述血孢子虫寄生虫有分子标记，呼吁研究人员填补这一空白。
