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  1. Article ; Online: The 18S rRNA genes of Haemoproteus (Haemosporida, Apicomplexa) parasites from European songbirds with remarks on improved parasite diagnostics.

    Harl, Josef / Himmel, Tanja / Ilgūnas, Mikas / Valkiūnas, Gediminas / Weissenböck, Herbert

    Malaria journal

    2023  Volume 22, Issue 1, Page(s) 232

    Abstract: 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 ... ...

    Abstract 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.
    Methods: The almost complete 18S rRNA genes of 19 Haemoproteus lineages of the subgenus Parahaemoproteus, which are common in passeriform birds from the Palaearctic, were sequenced. The PCR products of 20 blood and tissue samples containing 19 parasite lineages were subjected to molecular cloning, and ten clones in mean were sequenced each. The sequence features were analysed and phylogenetic trees were calculated, including sequence data published previously from eight additional Parahaemoproteus lineages. The geographic and host distribution of all 27 lineages was visualised as CytB haplotype networks and pie charts. Based on the 18S sequence data, species-specific oligonucleotide probes were designed to target the parasites in host tissue by in situ hybridization assays.
    Results: Most Haemoproteus lineages had two or more variants of the 18S gene like many Plasmodium species, but the maximum distances between variants were generally lower. Moreover, unlike in most mammalian and avian Plasmodium species, the 18S sequences of all but one parasite lineage clustered into reciprocally monophyletic clades. Considerably distinct 18S clusters were only found in Haemoproteus tartakovskyi hSISKIN1 and Haemoproteus sp. hROFI1. The presence of chimeric 18S variants in some Haemoproteus lineages indicates that their ribosomal units rather evolve in a semi-concerted fashion than according to a strict model of birth-and-death evolution.
    Conclusions: Parasites of the subgenus Parahaemoproteus contain distinct 18S variants, but the intraspecific variability is lower than in most mammalian and avian Plasmodium species. The new 18S data provides a basis for more thorough investigations on the development of Haemoproteus parasites in host tissue using in situ hybridization techniques targeting specific parasite lineages.
    MeSH term(s) Animals ; Haemosporida ; Songbirds ; Parasites ; Phylogeny ; RNA, Ribosomal, 18S/genetics ; Genes, rRNA ; Bird Diseases/parasitology ; Apicomplexa/genetics ; Plasmodium/genetics ; Mammals/genetics ; Protozoan Infections, Animal/parasitology
    Chemical Substances RNA, Ribosomal, 18S
    Language English
    Publishing date 2023-08-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 2091229-8
    ISSN 1475-2875 ; 1475-2875
    ISSN (online) 1475-2875
    ISSN 1475-2875
    DOI 10.1186/s12936-023-04661-9
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  2. Article ; Online: Exo-erythrocytic development of two Haemoproteus species (Haemosporida, Haemoproteidae), with description of Haemoproteus dumbbellus, a new blood parasite of bunting birds (Emberizidae).

    Duc, Mélanie / Himmel, Tanja / Ilgūnas, Mikas / Eigirdas, Vytautas / Weissenböck, Herbert / Valkiūnas, Gediminas

    International journal for parasitology

    2023  Volume 53, Issue 10, Page(s) 531–543

    Abstract: ... infection were selected for histological investigations. H & E-stained sections were screened for detection ... with the lineage hEMCIR01. Meronts of H. dumbbellus n. sp. developed in various organs of five of six tested ... probe. While the development of meronts seems to be typical for species of the clade containing H ...

    Abstract 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. More research is needed to better understand the patterns of the parasites' development in tissues and their impact on avian hosts. Yellowhammers Emberiza citrinella (Emberizidae) and common house martins Delichon urbicum (Hirundinidae) were screened for Haemoproteus parasites by microscopic examination of blood films and PCR-based testing. Individuals with single infection were selected for histological investigations. H & E-stained sections were screened for detection and characterization of the exo-erythrocytic stages, while chromogenic in situ hybridization (CISH) and phylogenetic analysis were performed to confirm the Haemoproteus origin and their phylogenetic relationships. Haemoproteus dumbbellus n. sp. was discovered in Emberiza citrinella single-infected with the lineage hEMCIR01. Meronts of H. dumbbellus n. sp. developed in various organs of five of six tested individuals, a pattern which was reported in other Haemoproteus species clustering in the same clade, suggesting this could be a phylogenetic trait. By contrast, in Delichon urbicum infected with the Haemoproteus lineage hDELURB2, which was linked to the more distantly related parasite Haemoproteus hirundinis, only megalomeronts were found in the pectoral muscles of two of six infected individuals. All exo-erythrocytic stages were confirmed to be Haemoproteus parasites by CISH using a Haemoproteus genus-specific probe. While the development of meronts seems to be typical for species of the clade containing H. dumbbellus, further investigations and data from more species are needed to explore whether a phylogenetic pattern occurs in meront or megalomeront formation.
    MeSH term(s) Humans ; Animals ; Haemosporida ; Parasites ; Phylogeny ; Bird Diseases/epidemiology ; Bird Diseases/parasitology ; Protozoan Infections, Animal/epidemiology ; Protozoan Infections, Animal/parasitology ; Passeriformes/parasitology ; Ceratopogonidae/parasitology ; Cytochromes b/genetics
    Chemical Substances Cytochromes b (9035-37-4)
    Language English
    Publishing date 2023-05-30
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 120518-3
    ISSN 1879-0135 ; 0020-7519
    ISSN (online) 1879-0135
    ISSN 0020-7519
    DOI 10.1016/j.ijpara.2023.02.009
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  3. Article ; Online: A citizen science-based survey of avian mortality focusing on haemosporidian infections in wild passerine birds.

    Himmel, Tanja / Harl, Josef / Matt, Julia / Weissenböck, Herbert

    Malaria journal

    2021  Volume 20, Issue 1, Page(s) 417

    Abstract: Background: Haemosporidioses are common in birds and their manifestations range from subclinical infections to severe disease, depending on the involved parasite and bird species. Clinical haemosporidioses are often observed in non-adapted zoo or aviary ...

    Abstract Background: Haemosporidioses are common in birds and their manifestations range from subclinical infections to severe disease, depending on the involved parasite and bird species. Clinical haemosporidioses are often observed in non-adapted zoo or aviary birds, whereas in wild birds, particularly passerines, haemosporidian infections frequently seem to be asymptomatic. However, a recent study from Austria showed pathogenic haemosporidian infections in common blackbirds due to high parasite burdens of Plasmodium matutinum LINN1, a common parasite in this bird species, suggesting that virulent infections also occur in natural hosts. Based on these findings, the present study aimed to explore whether and to what extent other native bird species are possibly affected by pathogenic haemosporidian lineages, contributing to avian morbidity.
    Methods: Carcasses of passerine birds and woodpeckers were collected during a citizen science-based survey for avian mortality in Austria, from June to October 2020. Tissue samples were taken and examined for haemosporidian parasites of the genera Plasmodium, Haemoproteus and Leucocytozoon by nested PCR and sequencing the mitochondrial cytb barcode region, histology, and chromogenic in situ hybridization applying genus-specific probes.
    Results: From over 160 dead bird reportings, 83 carcasses of 25 avian species were submitted for investigation. Overall haemosporidian infection rate was 31%, with finches and tits prevailing species counts and infections. Sequence analyses revealed 17 different haplotypes (4 Plasmodium, 4 Haemoproteus, 9 Leucocytozoon), including 4 novel Leucocytozoon lineages. Most infected birds presented low parasite burdens in the peripheral blood and tissues, ruling out a significant contribution of haemosporidian infections to morbidity or death of the examined birds. However, two great tits showed signs of avian malaria, suggesting pathogenic effects of the detected species Plasmodium relictum SGS1 and Plasmodium elongatum GRW06. Further, exo-erythrocytic tissue stages of several haemosporidian lineages are reported.
    Conclusions: While suggesting generally little contribution of haemosporidian infections to mortality of the investigated bird species, the findings indicate a possible role of certain haemosporidian lineages in overall clinical manifestation, either as main causes or as concurrent disease agents. Further, the study presents new data on exo-erythrocytic stages of previously reported lineages and shows how citizen science can be used in the field of haemosporidian research.
    MeSH term(s) Animals ; Animals, Wild ; Austria/epidemiology ; Bird Diseases/mortality ; Bird Diseases/parasitology ; Citizen Science ; Haemosporida/physiology ; Prevalence ; Protozoan Infections, Animal/epidemiology ; Protozoan Infections, Animal/parasitology ; Songbirds
    Language English
    Publishing date 2021-10-23
    Publishing country England
    Document type Journal Article
    ISSN 1475-2875
    ISSN (online) 1475-2875
    DOI 10.1186/s12936-021-03949-y
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  4. Article ; Online: MULTIPLE EPIDEMICS IN AUSTRIAN FRINGILLIDAE CAUSED BY A SINGLE VARIANT OF SALMONELLA TYPHIMURIUM.

    Brunthaler, René / Spergser, Joachim / Weissenböck, Herbert

    Journal of wildlife diseases

    2021  Volume 57, Issue 4, Page(s) 891–899

    Abstract: In Austria, numerous deaths of wild birds of the order Passeriformes, family Fringillidae, occurred during the winter months of 2010 and 2012. The Eurasian Siskin (Carduelis spinus) was the species most often affected. The dead birds were mainly found in ...

    Abstract In Austria, numerous deaths of wild birds of the order Passeriformes, family Fringillidae, occurred during the winter months of 2010 and 2012. The Eurasian Siskin (Carduelis spinus) was the species most often affected. The dead birds were mainly found in the immediate vicinity of feeding places. Vigilant citizens sent birds (n=34) for pathologic examination to the Institute of Pathology in Vienna, Austria. All birds were cachectic or in a very poor nutritional condition. At gross examination, the most striking findings were multifocal to confluent, yellow-white nodules in the crop or esophageal mucosa. In histologically examined birds (n=24), severe transmural fibrino-purulent to necrotizing ingluviitis or esophagitis with large amounts of intralesional bacteria was observed. Bacteriologic examination of crop, liver, or other organs from 14 birds revealed abundant growth of Salmonella serovar Typhimurium (antigenic formula 1,4,5,12:i:1,2; phage type U277) in all individuals. By means of immunohistochemistry, these bacteria were detected not only in crop mucosa but also in lung tissue. In 17 birds (71%), structures morphologically resembling Macrorhabdus ornithogaster were detected histologically on the surface of the proventricular epithelium. Thus, the cause of mass mortality of the passerine birds was identified as infection with Salmonella Typhimurium, which was associated with growth of presumed M. ornithogaster in many cases.
    MeSH term(s) Animals ; Austria/epidemiology ; Bird Diseases/microbiology ; Epidemics ; Passeriformes/microbiology ; Salmonella Infections, Animal/epidemiology ; Salmonella typhimurium
    Language English
    Publishing date 2021-08-20
    Publishing country United States
    Document type Journal Article
    ZDB-ID 410709-3
    ISSN 1943-3700 ; 0090-3558
    ISSN (online) 1943-3700
    ISSN 0090-3558
    DOI 10.7589/JWD-D-20-00178
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Unexpected absence of exo-erythrocytic merogony during high gametocytaemia in two species of

    Valkiūnas, Gediminas / Iezhova, Tatjana / Ilgūnas, Mikas / Tchoumbou, Mélanie / Duc, Mélanie / Bukauskaitė, Dovilė / Himmel, Tanja / Harl, Josef / Weissenböck, Herbert

    International journal for parasitology. Parasites and wildlife

    2024  Volume 23, Page(s) 100905

    Abstract: Neglected avian blood parasites of the ... ...

    Abstract Neglected avian blood parasites of the genus
    Language English
    Publishing date 2024-01-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 2715239-X
    ISSN 2213-2244
    ISSN 2213-2244
    DOI 10.1016/j.ijppaw.2024.100905
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  6. Article ; Online: RNAscope in situ hybridization reveals microvascular sequestration of Plasmodium relictum pSGS1 blood stages but absence of exo-erythrocytic dormant stages during latent infection of Serinus canaria.

    Himmel, Tanja / Harl, Josef / Matt, Julia / Nedorost, Nora / Iezhova, Tatjana / Ilgūnas, Mikas / Valkiūnas, Gediminas / Weissenböck, Herbert

    Malaria journal

    2024  Volume 23, Issue 1, Page(s) 70

    Abstract: 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 ...

    Abstract 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. This study investigated persistence of Plasmodium relictum pSGS1 in birds with latent infections during winter, with the goal to detect presumed persisting tissue stages using a highly sensitive RNAscope® in situ hybridization technology.
    Methods: Fourteen domestic canaries were infected with P. relictum pSGS1 by blood-inoculation in spring, and blood films examined during the first 4 months post infection, and during winter and spring of the following year. After parasitaemia was no longer detectable, half of the birds were dissected, and tissue samples investigated for persisting tissue stages using RNAscope ISH and histology. The remaining birds were blood-checked and dissected after re-appearance of parasitaemia, and their tissues equally examined.
    Results: Systematic examination of tissues showed no exo-erythrocytic stages in birds exhibiting latent infections by blood-film microscopy, indicating absence of dormant tissue stages in P. relictum pSGS1-infected canaries. Instead, RNAscope ISH revealed rare P. relictum blood stages in capillaries of various tissues and organs, demonstrating persistence of the parasites in the microvasculature. Birds examined after re-appearance of parasitemia showed higher numbers of P. relictum blood stages in both capillaries and larger blood vessels, indicating replication during early spring and re-appearance in the peripheral circulation.
    Conclusions: The findings suggest that persistence of P. relictum pSGS1 during latent infection is mediated by continuous low-level erythrocytic merogony and possibly tissue sequestration of infected blood cells. Re-appearance of parasitaemia in spring seems to result from increased erythrocytic merogony, therefore representing recrudescence and not relapse in blood-inoculated canaries. Further, the study highlights strengths and limitations of the RNAscope ISH technology for the detection of rare parasite stages in tissues, providing directions for future research on persistence and tissue sequestration of avian malaria and related haemosporidian parasites.
    MeSH term(s) Animals ; Canaries/parasitology ; Malaria, Avian/parasitology ; Plasmodium/genetics ; Birds ; In Situ Hybridization ; Parasitemia/parasitology ; Latent Infection ; Recurrence
    Language English
    Publishing date 2024-03-08
    Publishing country England
    Document type Journal Article
    ZDB-ID 2091229-8
    ISSN 1475-2875 ; 1475-2875
    ISSN (online) 1475-2875
    ISSN 1475-2875
    DOI 10.1186/s12936-024-04899-x
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  7. Article: Isospora

    Keckeisen, Carina / Šujanová, Alžbeta / Himmel, Tanja / Matt, Julia / Nedorost, Nora / Chagas, Carolina R F / Weissenböck, Herbert / Harl, Josef

    Pathogens (Basel, Switzerland)

    2024  Volume 13, Issue 4

    Abstract: Wild birds are common hosts to numerous intracellular parasites such as single-celled eukaryotes of the family Eimeriidae (order Eucoccidiorida, phylum Apicomplexa). We investigated the infection rates, phylogeny, and pathogenicity ... ...

    Abstract Wild birds are common hosts to numerous intracellular parasites such as single-celled eukaryotes of the family Eimeriidae (order Eucoccidiorida, phylum Apicomplexa). We investigated the infection rates, phylogeny, and pathogenicity of
    Language English
    Publishing date 2024-04-18
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2695572-6
    ISSN 2076-0817
    ISSN 2076-0817
    DOI 10.3390/pathogens13040337
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  8. Article: Exo-erythrocytic development of

    Chagas, Carolina Romeiro Fernandes / Duc, Mélanie / Himmel, Tanja / Eigirdas, Vytautas / Weissenböck, Herbert / Valkiūnas, Gediminas

    International journal for parasitology. Parasites and wildlife

    2023  Volume 22, Page(s) 60–68

    Abstract: ... ...

    Abstract Leucocytozoon
    Language English
    Publishing date 2023-08-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 2715239-X
    ISSN 2213-2244
    ISSN 2213-2244
    DOI 10.1016/j.ijppaw.2023.08.008
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  9. Article ; Online: Rustrela Virus-Associated Encephalomyelitis ('Staggering Disease') in Cats from Eastern Austria, 1994-2016.

    Weiss, Viktoria / Weidinger, Pia / Matt, Julia / Weissenbacher-Lang, Christiane / Nowotny, Norbert / Weissenböck, Herbert

    Viruses

    2023  Volume 15, Issue 8

    Abstract: Clinical cases of 'staggering disease', a nonsuppurative encephalomyelitis associated with gait abnormalities in cats, have been documented for decades in Sweden. In Austria, an increased incidence was observed in the 1990s. Only recently, rustrela virus ...

    Abstract Clinical cases of 'staggering disease', a nonsuppurative encephalomyelitis associated with gait abnormalities in cats, have been documented for decades in Sweden. In Austria, an increased incidence was observed in the 1990s. Only recently, rustrela virus (RusV) was identified as the causative agent of this clinicopathologic disease entity. In this retrospective study, we analyzed a total of 23 brain and spinal cord samples from Austrian cats with the pathohistological diagnosis of nonsuppurative encephalomyelitis and clinical signs consistent with staggering disease from 1994 to 2016 using reverse transcription real-time polymerase chain reaction (RT-qPCR) and in situ hybridization. We were able to detect RusV nucleic acids in seven of the examined samples. Borna disease virus 1 (BoDV-1) could be excluded in all cases via immunohistochemistry and RT-qPCR. This study confirms that RusV has been a relevant etiological agent of nonsuppurative encephalomyelitis of cats in a geographically and temporally limited disease cluster in Austria, mainly in the 1990s. The geographic distribution of the positive samples in this study is consistent with earlier reports on 'staggering disease' in Austria. Further studies are necessary to confirm the reservoir host of 'staggering disease' in Austria, as well as investigations on the disappearance of this disease and its possible zoonotic potential.
    MeSH term(s) Cats ; Animals ; Austria/epidemiology ; Retrospective Studies ; Brain ; Spinal Cord ; Encephalomyelitis
    Language English
    Publishing date 2023-07-25
    Publishing country Switzerland
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2516098-9
    ISSN 1999-4915 ; 1999-4915
    ISSN (online) 1999-4915
    ISSN 1999-4915
    DOI 10.3390/v15081621
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  10. Article: Exo-Erythrocytic Development of Avian Haemosporidian Parasites in European Owls.

    Ilgūnas, Mikas / Himmel, Tanja / Harl, Josef / Dagys, Mindaugas / Valkiūnas, Gediminas / Weissenböck, Herbert

    Animals : an open access journal from MDPI

    2022  Volume 12, Issue 17

    Abstract: 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 ...

    Abstract 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. Particularly little is known about the exo-erythrocytic development of avian haemosporidians. The goal of this study was to gain new knowledge about the parasites infecting owls in Europe and investigate their exo-erythrocytic stages. Tissue samples of 121 deceased owls were collected in Austria and Lithuania, and examined using polymerase chain reactions (PCR), histology, and chromogenic in situ hybridization (CISH). PCR-based diagnostics showed a total prevalence of 73.6%, revealing two previously unreported
    Language English
    Publishing date 2022-08-28
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2606558-7
    ISSN 2076-2615
    ISSN 2076-2615
    DOI 10.3390/ani12172212
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