Isospora svecica sp. n. (Apicomplexa: Eimeriidae), a new species of coccidium from the white-spotted bluethroat Luscinia svecica cyanecula (Aves: Passeriformes: Muscicapidae)

Isospora and Lankesterella Parasites (Eimeriidae, Apicomplexa) of Passeriform Birds in Europe: Infection Rates, Phylogeny, and Pathogenicity

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 Isospora and Lankesterella parasites in wild and captive passerine birds. Blood and tissue samples of 815 wild and 15 deceased captive birds from Europe were tested using polymerase chain reaction and partial sequencing of the mitochondrial cytochrome b and cytochrome c oxidase I and the nuclear 18S rRNA gene. The infection rate for Lankesterella in wild birds was 10.7% compared to 5.8% for Isospora. Chromogenic in situ hybridization with probes targeting the parasites' 18S rRNA was employed to identify the parasites' presence in multiple organs, and hematoxylin-eosin staining was performed to visualize the parasite stages and assess associated lesions. Isospora parasites were mainly identified in the intestine, spleen, and liver. Extraintestinal tissue stages of Isospora were accompanied by predominantly lymphohistiocytic inflammation of varying severity. Lankesterella was most frequently detected in the spleen, lung, and brain; however, infected birds presented only a low parasite burden without associated pathological changes. These findings contribute to our understanding of Isospora and Lankesterella parasites in wild birds.

Unique Isospora-associated histologic lesions in white-rumped shama (Copsychus malabaricus)

Twenty-one white-rumped shamas (19 necropsied, 2 biopsied) (Copsychus malabaricus) housed at the San Diego Zoo between 1992 and 2020 were diagnosed with Isospora infection based on evaluation of histologic sections. Review of these cases revealed a consistent histologic lesion characterized by nodular aggregates of atypical epithelioid macrophages containing few intracytoplasmic protozoa, with or without lymphocytic infiltrates. Of the 19 necropsied cases, 16 (84%) had systemic lesions variably affecting the liver, spleen, gastrointestinal tract, lung, pancreas, connective tissues, or bone marrow, while all 21 diagnosed cases had skin involvement. The findings suggest that white-rumped shamas have a unique inflammatory response to isosporosis with a predilection for the skin. Skin may be a diagnostically sensitive sampling site for histologic diagnosis of Isospora in this species.

The First Isospora Species (Apicomplexa: Eimeriidae) Described from the Northern Yellow-Shafted Flicker (Colaptes auratus luteus) in Ontario, Canada

PURPOSE

Members of the genus Isospora commonly infect a wide variety of wild birds. By combining morphometric and genetic data, we are able to differentiate and describe a new apicomplexan parasite, Isospora picoflavae n. sp., from the Northern Yellow-shafted Flicker (Colaptes auratus luteus) in Ontario, Canada.

METHODS

Unsporulated oocysts were observed in intestinal contents obtained during necropsy; these oocysts completed exogenous sporulation within 7 days at room temperature. Complete nuclear 18S rDNA and complete mitochondrial genome sequences were obtained from this previously undescribed Isospora sp. to compare with related coccidia.

RESULTS

Sporulated oocysts were subspherical in shape measuring an average of 22.7 × 21.7 μm (n = 53; mean shape index 1.05) containing a near-spherical polar granule. Sporocysts were ovoidal to ellipsoidal in shape, measuring an average size of 17.0 × 10.5 μm (n = 9; mean shape index 1.62). Sporocyst residuum was concentrated in an irregular, spherical mass in the middle of each sporocyst. The isolated oocysts differed morphologically from other Isospora species reported to infect members of the family Picidae. Based on phylogenetic analyses using either combined nuclear 18S rDNA and mitochondrial cytochrome c oxidase I (COI) sequences or complete mitochondrial genome sequences, this Isospora sp. n. isolated from the Northern Flicker grouped within a clade containing Isospora species described from various passeriform hosts.

CONCLUSION

Based on combined morphological and molecular data, the oocysts found in the gastrointestinal contents of Colaptes auratus luteus represent a new species of Isospora named herein as Isospora picoflavae n. sp.

Isospora basileuterusi n. sp. (Apicomplexa: Eimeriidae) from the golden-crowned warbler Basileuterus culicivorus (Deppe) (Passeriformes: Parulidae) in South America

Isospora basileuterusi Mello & Berto n. sp. is described based on material from the golden-crowned warbler Basileuterus culicivorus (Deppe) captured in the Itatiaia National Park (Parque Nacional do Itatiaia), a conservation unit in south-eastern Brazil. Oöcysts of the new species are ellipsoidal to ovoidal, measuring on average 25.2 × 21.1 μm, with a smooth, bi-layered wall, c.1.6 μm thick. Micropyle and oöcyst residuum are both absent, but one to three polar granules are present. Sporocysts are ellipsoidal to lemon-shaped, measuring on average 15.3 × 9.5 μm, with a knob-like Stieda body and a trapezoidal sub-Stieda body. Sporocyst residuum is present, usually as a body of membrane-bound granules. Sporozoites are vermiform, with refractile bodies. Four of the 19 warblers captured (21%) were infected with the new species. Molecular analysis of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene revealed a similarity of 99.5% between the new species and Isospora serinuse Yang, Brice, Elliot & Ryan, 2015 from island canaries Serinus canaria (L.) in Western Australia. The oöcysts of I. basileuterusi n. sp. can be distinguished from the four other Isospora spp. recorded in hosts of the Parulidae, and from the molecularly most closely related species, by the typical ellipsoidal to lemon-shaped sporocysts, with small sub-Stieda body and a membrane-bound sporocyst residuum. Therefore, based on the morphological and molecular features, I. basileuterusi n. sp. is the fifth species described in a host of the family Parulidae and the first molecularly characterized via sequencing the cox1 gene.

Isospora oliveirai n. sp. (Chromista: Miozoa: Eimeriidae) from the Greenish Schiffornis Schiffornis virescens (Lafresnaye, 1838) (Passeriformes: Tyranni: Tityridae) in South America

BACKGROUND

Coccidia are obligatory intracellular parasites with at least one intestinal phase in their life cycles, being Isospora Schneider, 1881 the main coccidian genus related to the order Passeriformes. However, there is no record of isosporans from the passerine family Tityridae, which is the family of the greenish schiffornis Schiffornis virescens (Lafresnaye, 1838).

PURPOSE

This study aimed to examine the faeces from a greenish schiffornis S. virescens captured in the Itatiaia National Park, State of Rio de Janeiro, Southeastern Brazil, to determine what coccidian parasites were present.

METHODS

Only one specimen of Schiffornis virescens was captured with mist nets. Coccidian oocysts were recovered from the fecal samples by flotation in Sheather's saturated solution. Morphological observations, line drawings, photomicrographs and measurements were made in optical microscopy and digitally edited. The molecular analysis included the study of the sequence of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene, with phylogenetic reconstructions based on the Neighbor-Joining and Maximum Likelihood analysis.

RESULTS

An Isospora sp. considered as new to science is described and identified from Schiffornis virescens (Lafresnaye, 1838). Isospora oliveirai n. sp. has oocysts that are subspheroidal, 26.0 × 24.8 μm, with rough, bilayered wall, c.2.5 μm thick. Micropyle and oocyst residuum absent, but one to six polar granules are present. Sporocysts lemon-shaped, 18.1 × 10.9 μm. The Stieda body is knob-like to half-moon-shaped and sub-Stieda is rounded. Sporocyst residuum is present, composed of scattered spherules of different sizes. Sporozoites are vermiform, with refractile bodies and nucleus. Molecular analysis at the COI gene exhibited similarity of 97% with Isospora serinuse Yang, Brice, Elliot et Ryan, 2015 from island canaries Serinus canaria (Linnaeus, 1758), and Isospora spp. from great tits Parus major (Linnaeus, 1758) and European robins Erithacus rubecula (Linnaeus, 1758).

CONCLUSION

Based on the morphological and molecular features, I. oliveirai is considered as new to science and the first coccidian species recorded from Tityridae.