Abstract
BackgroundBlood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood (circulating microfilariae) of birds belonging to many orders. Current limitations in molecular characterization methods and species identification using morphological characters of circulating microfilariae are major obstacles to improving our understanding the biology of Filarioidea species, particularly in wildlife. The aim of this study was to partially fill these gaps, with particular emphasis on morphological features of microfilariae, which are the most readily accessible stages of these pathogens.MethodsPeripheral blood samples of 206 birds belonging to genera Acrocephalus (five species) and Sylvia (five species) were examined using the buffy coat method to process the blood samples for the presence of microfilariae. Positive birds were dissected to collect adult nematodes. Microfilariae and adult nematodes were described, and sequences of their mitochondrial cytochrome c oxidase subunit I and nuclear 28S rDNA gene fragments were obtained and used for molecular characterization and Bayesian phylogenetic inferences.ResultsOverall prevalence of microfilariae was 2.9%. Microfilariae were found in the blood samples from six birds (2 Acrocephalus scirpaceus and 1 each of A. arundinaceus, Sylvia atricapilla, S. borin and S. curruca), which were dissected. All parasite species observed were new. Eufilaria acrocephalusi sp. n. and Eufilaria sylviae sp. n. were present in subcutaneous, peritracheal and periesophageal connective tissues in A. scirpaceus and S. borin, respectively. Splendidofilaria bartletti sp. n. was found in finger joins of S. atricapilla. Illustrations of microfilariae and adult nematodes are shown, and morphological and phylogenetic analyses identified the DNA barcode haplotypes that are associated with these species. Phylogenetic analysis places the parasites of different genera in different closely related clades.ConclusionsAdult nematode morphological characters, which have been traditionally used in the taxonomy of Filarioidea species, have a phylogenetic value. Importantly, in our study parasites of different genera were readily distinguishable based on the morphology of their microfilariae. The link between molecular and morphology data requires more study in Filarioidea species research, particularly because this approach provides new knowledge on species identity using only readily accessible blood stages (microfilariae), thereby avoiding host dissection and thus minimizing harm to wildlife during research.Graphical
Highlights
Blood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood of birds belonging to many orders
Blood parasites have been the subject of much research, with numerous reports of microfilariae of nematodes of the superfamily Filarioidea being present in the peripheral blood of birds belonging to many orders [1,2,3]
Microfilariae were seen in six birds (2 common reed warblers Acrocephalus scirpaceus, 1 great reed warbler Acrocephalus arundinaceus, 1 Eurasian blackcap Sylvia atricapilla, one garden warbler Sylvia borin and one lesser whitethroat Sylvia curruca)
Summary
Blood parasites have been the subject of much research, with numerous reports of the presence of microfilariae in the peripheral blood (circulating microfilariae) of birds belonging to many orders. Blood parasites have been the subject of much research, with numerous reports of microfilariae of nematodes of the superfamily Filarioidea being present in the peripheral blood (circulating microfilariae) of birds belonging to many orders [1,2,3]. There are many studies on the filarioids of birds, the majority of these have focused on economically important or pet bird species [4], and much less data are available on the parasites of birds naturally occurring in the wild state, including the widely distributed warbles belonging to genera Sylvia and Acrocephalus. The species diversity of avian filarioid nematodes remains insufficiently explored, with the last available description of a new species published by Bartlett in 1992 [6]
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