Publications by authors named "Gediminas Valkiunas"

sp. nov. (Haemosporida, Haemoproteidae) was found in the dunnock and represents the first blood parasite described in accentor birds of the Prunellidae.

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Article Synopsis
  • * Infections were confirmed through microscopic examination and PCR methods, revealing the presence of exo-erythrocytic meronts of Haemoproteus attenuatus in various organs, primarily in the lungs.
  • * The research also discovered megalomeronts related to Haemoproteus majoris, indicating potential abortive infections, which are rarely documented in wild birds, thus contributing new insights into parasite development in avian hosts.
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Background: Birds chronically infected with avian malaria parasites often show relapses of parasitaemia after latent stages marked by absence of parasites in the peripheral circulation. These relapses are assumed to result from the activation of dormant exo-erythrocytic stages produced during secondary (post-erythrocytic) merogony of avian Plasmodium spp. Yet, there is no morphological proof of persistent or dormant tissue stages in the avian host during latent infections.

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Article Synopsis
  • Species from the subgenus Novyella, specifically Plasmodium (Novyella) homonucleophilum, are poorly studied avian malaria agents with a broad transmission range in the Old World, including Europe.
  • This study is the first to document the infection process of P. homonucleophilum in Eurasian siskins, where all exposed birds showed susceptibility and three out of six died, indicating a high virulence of the parasite.
  • The findings suggest significant impacts on the health of infected birds, such as increased parasitaemia, decline in red blood cell count (anaemia), and increased food intake to compensate for energy loss, highlighting the need for further research on these neglected malaria parasites.
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Haemoproteus blood parasites of birds are thought to be relatively benign. Recent findings show that infections may develop in the brain of birds, possibly distorting their orientation sense. Misdirected migration may lead migrants outside their range where they are recognized as vagrants and can transmit parasites to novel hosts.

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Haemoproteus species (Haemosporida, Haemoproteidae) are cosmopolitan and highly diverse blood parasites of birds that have been neglected in avian medicine. However, recent discoveries based on molecular diagnostic markers show that these pathogens often cause marked damage to various internal organs due to exo-erythrocytic development, sometimes resulting in severe and even lethal avian haemoproteosis, including cerebral pathologies. Molecular markers are essential for haemoproteosis diagnostics, but the data is limited, particularly for parasites transmitted in tropical ecosystems.

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Article Synopsis
  • * This study investigates Haemoproteus parasites in 16 species of accipitriform raptors, using both morphological and molecular methods, resulting in the identification of two new species, including one named H. multivacuolatus n. sp.
  • * The findings reveal significant genetic divergence in the cytb sequences of these parasites, suggesting the need for new diagnostic methods to identify these unique and possibly under-recognized haemosporidian parasites.
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Neglected avian blood parasites of the genus (Haemoproteidae) have recently attracted attention due to the application of molecular diagnostic tools, which unravelled remarkable diversity of their exo-erythrocytic (or tissue) stages both regarding morphology and organ tropism levels. The development of haemoproteids might result in pathologies of internal organs, however the exo-erythrocytic development (EED) of most species remains unknown. Seven individual birds - (1) and (6) - with high gametocytaemia (between 1% and 24%) of n.

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parasites (Haemosporida, Leucocytozoidae) are haemosporidians whose diversity, exo-erythrocytic development and potential vectors are the least studied. The knowledge about their exo-erythrocytic development and pathogenicity is fragmentary, resulting in an incomplete comprehension of the impact of these parasites on avian hosts. For a long time, infections were considered benign to wild birds, even though they were virulent in poultry and responsible for some wild bird population declines.

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Avian haemosporidians of the genera Plasmodium, Haemoproteus, and Leucocytozoon are common blood parasites in wild birds all over the world. Despite their importance as pathogens potentially compromising host fitness and health, little is known about the exo-erythrocytic development of these parasites, particularly during co-infections which predominate in wildlife. This study aimed to address this issue using Haemoproteus parasites of Fringilla coelebs, a common bird species of the Western Palearctic and host to a variety of haemosporidian parasite lineages.

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Background: The nuclear ribosomal RNA genes of Plasmodium parasites are assumed to evolve according to a birth-and-death model with new variants originating by duplication and others becoming deleted. For some Plasmodium species, it has been shown that distinct variants of the 18S rRNA genes are expressed differentially in vertebrate hosts and mosquito vectors. The central aim was to evaluate whether avian haemosporidian parasites of the genus Haemoproteus also have substantially distinct 18S variants, focusing on lineages belonging to the Haemoproteus majoris and Haemoproteus belopolskyi species groups.

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parasites (Apicomplexa, Haemosporida) are widespread pathogens of birds, with a rich genetic (about 1900 lineages) and morphospecies (178 species) diversity. Nonetheless, their life cycles are poorly understood. The exo-erythrocytic stages of three (widespread generalist parasite) lineages have been previously reported, each in a different bird species.

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Blood parasites of the genus (Leucocytozoidae) only inhabit birds and represent a readily distinct evolutionary branch of the haemosporidians (Haemosporida, Apicomplexa). Some species cause pathology and even severe leucocytozoonosis in avian hosts, including poultry. The diversity of pathogens is remarkable, with over 1400 genetic lineages detected, most of which, however, have not been identified to the species level.

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Avian haemosporidians are widespread parasites categorized into four families of the order Haemosporida (Apicomplexa). Species of the subgenus Parahaemoproteus (genus Haemoproteus) belong to the Haemoproteidae and are transmitted by Culicoides biting midges. Reports of death due to tissue damage during haemoproteosis in non-adapted birds have raised concerns about these pathogens, especially as their exo-erythrocytic development is known for only a few Haemoproteus spp.

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parasites remain poorly investigated in comparison to other haemosporidians. The host cell inhabited by their blood stages (gametocytes) remains insufficiently known. This study aimed to determine the blood cells inhabited by gametocytes in different species of Passeriformes and to test if this feature has a phylogenetic importance.

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spp. are dipteran-borne protozoa that infect erythrocytes and reticulo-endothelial cells of birds. These parasites are not usually transmitted between birds belonging to different orders.

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Morphological traits from blood stages have been the gold standard for determining haemosporidian parasite species. However, the status of some taxa and the value of such traits in parasites from reptiles remain contentious. The scarce sampling of these species worsens the situation, and several taxa lack molecular data.

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Background: 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.

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Avian haemosporidian parasites (Haemosporida, Apicomplexa) are globally distributed and infect birds of many orders. These pathogens have been much investigated in domestic and wild passeriform birds, in which they are relatively easy to access. In birds belonging to other orders, including owls (order Strigiformes), these parasites have been studied fragmentarily.

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Among the primate malaria parasites, those found in lemurs have been neglected. Here, six Plasmodium lineages were detected in 169 lemurs. Nearly complete mitochondrial genomes (mtDNA, ≈6Kb) and apicoplast loci (≈6Kb) were obtained from these parasites and other Haemosporida species.

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Background: Species of Plasmodium (Haemosporida, Plasmodiidae) are remarkably diverse haemoparasites. Information on genetic diversity of avian malaria pathogens has been accumulating rapidly, however exo-erythrocytic development of these organisms remains insufficiently addressed. This is unfortunate because, contrary to Plasmodium species parasitizing mammals, the avian malaria parasites undergo several cycles of exo-erythrocytic development, often resulting in damage of various organs.

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Background: 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.

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We describe Leucocytozoon polynuclearis n. sp. (Haemosporida: Leucocytozoidae) from two North American woodpeckers, the northern flicker (Colaptes auratus Linnaeus) and white-headed woodpecker (Dryobates albolarvatus Boie, 1826), based on the morphology of its blood stages and portions of the mitochondrial cytochrome b gene.

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Article Synopsis
  • * A total of 39 CytB lineages were identified, with 18 recorded for the first time, highlighting the diversity and prevalence of these parasites in the studied populations.
  • * Chromogenic in situ hybridization confirmed the presence of specific stages of Leucocytozoon parasites, contributing to the overall understanding of parasite distribution in birds of prey.
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