The Genus Atoxoplasma (Garnham 1950) as a Junior Objective Synonym of the Genus Isospora (Schneider 1881) Species Infecting Birds and Resurrection of Cystoisospora (Frenkel 1977) as the Correct Genus for Isospora Species Infecting Mammals

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.

Systemic Caryospora-like coccidiosis in a clutch of hatchling red-eared slider turtles (Trachemys scripta elegans)

Caryospora-like organisms (CLOs) form a clade of at least 11 genotypes of related coccidia that can cause epizootic mortality in marine turtles. The biology, transmission, host species range, and host cell tropism of these organisms are still largely unknown. The goal of this study was to characterize the host cell tropism, pathologic and ultrastructural features, and phylogeny associated with the first report of a mortality event due to CLO in the freshwater red-eared slider turtle (Trachemys scripta elegans). Sudden mortalities within a clutch of captive-raised red-eared slider hatchlings (n = 8) were recorded, and deceased animals had severe segmental to diffuse, transmural, fibrinonecrotic enterocolitis and multifocal to coalescing hepatic necrosis, among other lesions associated with numerous intracytoplasmic developing stages of intralesional coccidia. Among the different developmental stages, merozoites were ultrastructurally characterized by an apical complex. A pan-apicomplexan polymerase chain reaction (PCR) yielded a 347 bp-amplicon matching the Schellackia/Caryospora-like clade with 99.1% identity to the US3 strain from green sea turtles (Chelonia mydas) and 99.1% identity to Schellackia sp. Isolate OC116. Surviving hatchlings were treated with toltrazuril sulfone (ponazuril) but were subsequently euthanized due to the risk of spreading the parasite to other chelonids in the collection. The ponazuril-treated hatchlings (n = 4) had mild proliferative anterior enteritis, with few intraepithelial coccidia in one hatchling confirmed as CLO by PCR. This is the first report of Caryospora-like coccidiosis in non-cheloniid turtles, highlighting the relevance of this disease as an emerging highly pathogenic intestinal and extra-intestinal form of coccidiosis of turtles with potential cross-species infectivity.

Morphological and molecular biology identification of Cystoisospora sp. in the blue fox, Alopex lagopus (Linnaeus, 1758)

To investigate the prevalence and molecular characteristics of Cystoisospora sp. in blue fox (Alopex lagopus), Sheather's sugar floatation method was conducted to detect coccidia in 423 fresh fecal samples randomly collected from blue fox farms from three cities in China. The overall prevalence of coccidia was 1.4% (6/423), and three Cystoisospora sp. (Cystoisospora fennechi, Cystoisospora sp. I and Cystoisospora vulpina) were identified by their morphological characteristics. The 18S ribosomal RNA (rRNA) and cytochrome c oxidase subunit I (COI) locus sequences were sequenced for molecular biological identification, homology comparison, and phylogenetic analysis of Cystoisospora sp. by single-oocyst selection technology and multi-locus-nested PCR amplification. At the 18S rRNA and COI loci, C. vulpina had 99.48% and 99.59% homology, respectively, with Cystoisospora canis and Cystoisospora ohioensis from canines. Phylogenetic analysis indicated that C. vulpina was clustered in a clade with Cystoisospora sp. from Canidae, which the relatives are consistent with the hosts. To our knowledge, this is the first report on molecular identification and evolutionary analysis of C. vulpina at two different loci.

Morphological and molecular characterization of Isospora elliotae n. sp. (Apicomplexa: Eimeriidae) from the Australian magpie Gymnorhina tibicen (Latham, 1801) (Passeriformes: Artamidae) in Western Australia

A new coccidian species, Isospora elliotae n. sp., from the Australian magpie Gymnorhina tibicen (Latham, 1801) in Western Australia, is described and characterized morphologically and molecularly. Microscopic analysis of a faecal sample identified subspheroidal oocysts (n = 20), 20-22 × 18-20 (20.7 × 18.7); length/width (L/W) ratio 1.05-1.14 (1.10). Wall bi-layered, 1.0-1.3 (1.2) thick, outer layer smooth, c. 2/3 of total thickness. Micropyle and oocyst residuum absent, but usually two polar granules are present. Sporocysts (n = 28) ovoidal, 12-13 × 9-11 (12.6 × 9.7); L/W ratio 1.22-1.35 (1.30). Stieda body present, flattened to half-moon-shaped, c. 0.5 deep × 2.0 wide; sub-Stieda indistinct or barely discernible, c. 1.0 deep × 2.5 wide; para-Stieda body absent; sporocyst residuum present, composed of granules dispersed among the sporozoites. Sporozoites vermiform, with anterior and posterior refractile bodies and nucleus. Segments of three gene loci (18S rRNA, 28S rRNA and COI) were sequenced and I. elliotae n. sp. exhibited 99.8% genetic similarity to Isospora sp. MAH-2013a (KF648870) followed by 99.7% genetic similarity to Isospora neochmiae (Yang, Brice & Ryan, 2016) (KT224380) at the 18S rRNA gene locus. It shared 97.0% genetic similarity with an unnamed Isospora sp. (AY283852) at the 28S rRNA gene locus and it also shared the highest genetic similarity of 99.8% with the unnamed Isospora sp. from an American crow (OL999120) at the COI gene locus. Based on morphological and molecular data, this isolate is a new species named as I. elliotae n. sp.

The Tubulin Superfamily in Apicomplexan Parasites

Microtubules and specialized microtubule-containing structures are assembled from tubulins, an ancient superfamily of essential eukaryotic proteins. Here, we use bioinformatic approaches to analyze features of tubulins in organisms from the phylum Apicomplexa. Apicomplexans are protozoan parasites that cause a variety of human and animal infectious diseases. Individual species harbor one to four genes each for α- and β-tubulin isotypes. These may specify highly similar proteins, suggesting functional redundancy, or exhibit key differences, consistent with specialized roles. Some, but not all apicomplexans harbor genes for δ- and ε-tubulins, which are found in organisms that construct appendage-containing basal bodies. Critical roles for apicomplexan δ- and ε-tubulin are likely to be limited to microgametes, consistent with a restricted requirement for flagella in a single developmental stage. Sequence divergence or the loss of δ- and ε-tubulin genes in other apicomplexans appears to be associated with diminished requirements for centrioles, basal bodies, and axonemes. Finally, because spindle microtubules and flagellar structures have been proposed as targets for anti-parasitic therapies and transmission-blocking strategies, we discuss these ideas in the context of tubulin-based structures and tubulin superfamily properties.

IDENTIFICATION AND RETROSPECTIVE EVALUATION OF A FILARIOID NEMATODE SPECIES IN MANAGED GRASSHOPPER SPARROWS (AMMODRAMUS SAVANNARUM)

The grasshopper sparrow (Ammodramus savannarum) is a species of ground-dwelling passerine bird with 12 different subspecies. The Florida subspecies (Ammodramus savannarum floridanus) is classified as federally endangered, with the most common threats including habitat loss, nest predation, and floods. A managed breeding program was established at White Oak Conservation (Yulee, FL) in 2015 with eastern grasshopper sparrows (Ammodramus savannarum pratensis) as a model for breeding Florida grasshopper sparrows as part of an assurance colony. A filarioid parasite species (Aproctella sp.) was characterized by PCR after identification by blood films and postmortem examinations of both subspecies housed at White Oak Conservation. This Aproctella species was distinct from others with available sequence. Records from 157 eastern and Florida grasshopper sparrows were reviewed, and correlations between presence of filariasis and subspecies, sex, body condition score, and presence of systemic isosporosis, squamous metaplasia, coelomitis, airsacculitis, or a combination of conditions were investigated. Twenty-nine (18.5%) birds (13 of 71 Florida grasshopper sparrows; 16 of 86 eastern grasshopper sparrows) were positive for filariasis by blood film review, grossly or by tissue imprint at postmortem examination, or histologically. Filariasis was significantly correlated with systemic isosporosis, coelomitis, and airsacculitis; was not correlated with subspecies, sex, or squamous metaplasia; and had a questionable correlation with body condition score. This report provides evidence that this Aproctella species has potential to contribute to morbidity and mortality in the grasshopper sparrow. This information will be helpful for implementing effective measures against suspected vectors and for the development of best practice strategies for the health management of the species in breeding programs.

Occurrence of Apicomplexa protozoa in wild birds in the Northeast region of Brazil

Protozoa of the Apicomplexa phylum are worldwide distributed with capacity to infect endothermic animals. The study of these protozoa in wild birds in Brazil is scarce. This study aimed to evaluate the occurrence of apicomplexan protozoa in wild birds in the Northeast of Brazil. From October to December 2019, brain tissue samples were collected from 71 captive birds from the Wild Animal Screening Center of the Pernambuco State (CETRAS-Tangara) and 25 free-living birds from the Caatinga biome in Rio Grande do Norte, totaling 96 animals (41 species). Brain fragments were subjected to molecular diagnosis by nested PCR for the 18s rDNA gene of Apicomplexa parasites, followed by DNA sequencing. This gene was detected in 25% (24/96) of the samples, and it was possible to perform DNA sequencing of 14 samples, confirming three genera: Isospora, Sarcocystis and Toxoplasma from eight bird species (Amazona aestiva, Coereba flaveola, Egretta thula, Paroaria dominicana, Sporophila nigricollis, Cariama cristata, Columbina talpacoti, Crypturellus parvirostris). The occurrence these coccidia in wild birds provides important epidemiological information for the adoption of preventive measures for its conservation. Future studies are needed to better understand the consequence of Apicomplexa infection in birds in Caatinga and Atlantic Forest biomes.

Mitochondrial Gene Diversity and Host Specificity of Isospora in Passerine Birds

Isospora infections are common in both wild and captive passerine species. Many bird species have been shown to have co-evolved with a particular species of Isospora. Disease can range from subclinical to severe and fatal, making infection and transmission of this parasite a concern for birds under managed care, particularly in institutions housing endangered species for breeding and reintroduction purposes. Whether birds in mixed-species enclosures represent a risk factor for severe isosporiasis due to infection with non-host-adapted strains is of concern for institutions managing these populations. To begin answering this question, we sought to characterize the host-specificity of Isospora spp. in a large number of passerine birds via retrospective sequencing of mitochondrial gene cytochrome c oxidase subunit I (COI). Despite outliers, Isospora sequences largely grouped by host species and/or host family. Additional research is warranted into the degree of interspecies transmission and host-switching of Isospora parasites, and risk factors for the development of severe disease in passerine birds.

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.

The transcriptome from asexual to sexual in vitro development of Cystoisospora suis (Apicomplexa: Coccidia)

The apicomplexan parasite Cystoisospora suis is an enteropathogen of suckling piglets with woldwide distribution. As with all coccidian parasites, its lifecycle is characterized by asexual multiplication followed by sexual development with two morphologically distinct cell types that presumably fuse to form a zygote from which the oocyst arises. However, knowledge of the sexual development of C. suis is still limited. To complement previous in vitro studies, we analysed transcriptional profiles at three different time points of development (corresponding to asexual, immature and mature sexual stages) in vitro via RNASeq. Overall, transcription of genes encoding proteins with important roles in gametes biology, oocyst wall biosynthesis, DNA replication and axonema formation as well as proteins with important roles in merozoite biology was identified. A homologue of an oocyst wall tyrosine rich protein of Toxoplasma gondii was expressed in macrogametes and oocysts of C. suis. We evaluated inhibition of sexual development in a host-free culture for C. suis by antiserum specific to this protein to evaluate whether it could be exploited as a candidate for control strategies against C. suis. Based on these data, targets can be defined for future strategies to interrupt parasite transmission during sexual development.

Chronic Cystoisospora belli infection in a Colombian patient living with HIV and poor adherence to highly active antiretroviral therapy

Cystoisospora belli is an intestinal Apicomplexan parasite associated with diarrheal illness and disseminated infections in humans, mainly immunocompromised individuals such as those living with the human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS). An irregular administration of highly active antiretroviral therapy (HAART) in HIV patients may increase the risk of opportunistic infections like cystoisosporiasis. We describe here a case of C. belli infection in a Colombian HIV patient with chronic gastrointestinal syndrome and poor adherence to HAART. His clinical and parasitological cure was achieved with trimethoprim-sulfamethoxazole treatment. Although a reduction in the number of C. belli cases has been observed since the use of HAART, this parasite still has to be considered as a differential diagnosis of diarrheal disease in HIV/AIDS patients. Effective interventions enhancing adherence to HAART should be included in HIV patient care programs.

Prevalence of coccidia in domestic pigs in China between 1980 and 2019: a systematic review and meta-analysis

BACKGROUND

Swine coccidiosis, a protozoan disease caused by coccidia, can result in diarrhoea and weight loss in piglets and even economic losses in the pig industry. Here, we report the first systematic review and meta-analysis of the prevalence of coccidia (including Eimeria spp. and Cystoisospora suis) in pigs in China.

METHODS

Five databases (PubMed, ScienceDirect, Chinese Web of Knowledge, Wanfang, and Chongqing VIP) were searched and 50 studies (46,926 domestic pigs, 22 provinces) ultimately identified pertaining to the prevalence of coccidia infection from 1980 to 2019. We incorporated the effect size using the random-effects model in the "meta" package in R software and conducted univariate and multivariate meta-regression analyses using a mixed-effects model.

RESULTS

The pooled prevalence rate of coccidia in pigs was 21.9%, including the C. suis infection rate of 9.1%. The highest prevalence of coccidia (39.6%) was found in northwest China, and this region also presented the lowest prevalence of C. suis (4.7%). In the subgroup analysis based on sampling year, the highest prevalence of coccidia was detected in 2001 or earlier (32.6%), whereas the lowest rate was found in 2012 or later (14.3%). An opposite trend was observed for C. suis (5.5% in 2000 or earlier vs 14.4% in 2000 or later). The prevalence of coccidia in extensive farming systems (29.5%) was higher than that in intensive farming systems (17.3%). In contrast, the point estimate of C. suis prevalence was lower in the extensive farming systems (5.1%) than in the intensive farming systems (10.0%), but the difference was not significant (P > 0.05). Among the four age categories, the highest total coccidia prevalence (26.2%) was found in finishing pigs, followed by suckling piglets (19.9%), whereas the highest prevalence of C. suis (14.9%) was observed in suckling piglets.

CONCLUSIONS

Our findings suggest that coccidia infection in Chinese pigs is common, although the prevalence of C. suis in pigs does not receive sufficient attention. We recommend the rational use of anticoccidial drugs to avoid drug resistance and the development of preventive and control measures for C. suis to reduce the incidence of swine coccidiosis.

Detection of Eumonospora henryae (Apicomplexa: Sarcocystidae) from Falco columbarius (Falconiformes: Aves): Comparison of host-parasite phylogram and comments on the family Sarcocystidae Poche, 1913

The genus Eumonospora Allen, 1933 (Apicomplexa: Sarcocystidae), an avian coccidia, is characterized by monosporocystic and octasporozoic oocysts without Stieda and substieda bodies. Some members of Eumonospora, which infect several raptor species, exhibit high levels of pathogenicity, making eumonosporiosis the leading cause of death in captive-bred raptors. The host specificity of these species appears to be mesostenoxenous, as evidenced by unsuccessful transmission between different orders of avian hosts. However, several studies have detected Eumonospora spp. in taxonomically distant avian hosts, indicating that some of these species may be euryxenous. In the current study, diarrheic fecal examination of a captive-bred juvenile merlin (Falconiformes: Aves) in Tokyo, Japan, was conducted, and a large number of oocysts were morphologically and molecularly identified as E. henryae (Yakimoff and Matschulsky, 1932), a coccidia species reported only in Strigiformes. This is a new recorded host for this coccidia. Phylogenetic analyses via Bayesian inference and maximum likelihood methods using concatenated genomic datasets consisting of nuclear 18S rDNA, nuclear 28S rDNA and mitochondrial cytochrome C oxidase subunit 1 gene, revealed a well-supported monophyletic clade of Eumonospora spp. belonging to the family Sarcocystidae Poche 1913, which largely corresponded to the avian host phylogram. Therefore, based on distinguishable oocyst morphology, a new subfamily, Eumonosporinae, within the family Sarcocystidae, is proposed, and a reconsideration of the definition of Sarcocystidae is suggested. Further molecular characterization of this emerging pathogen, as well as clarification of its complete life cycle, including cyst-forming ability, is required for more appropriate generic assessment.

Molecular characterization of enteric coccidia from domestic ferrets (Mustela putorius furo)

Combined morphometric and molecular characterization of coccidia that infect domestic ferrets (Mustela putorius furo) was completed to improve the diagnostic specificity of 'coccidiosis' in this host. Coccidia-positive fecal samples (n = 11) and formalin-fixed paraffin-embedded intestinal tissues (n = 3) from domestic ferrets were collected from diagnostic laboratories in Canada and Europe. An average of 3.5 and 13 domestic ferret fecal samples per year were coccidia-positive when tested by Canadian and European diagnostic laboratories, respectively, during the period 2008-2015. Oocyst morphometrics and sequence genotyping at two loci (nuclear 18S rDNA [nu 18S] and mitochondrial cytochrome c oxidase subunit I [mt COI]) were conducted on all samples. The first nu 18S and mt COI sequences for Cystoisospora laidlawi, and the first mt COI sequence for Eimeria furonis were generated during this study. Phylogenetic analysis of the mitochondrial COI sequences demonstrated that E. furonis was most closely related to E. ictidea isolated from a black-footed ferret (Mustela nigripes) and that C. laidlawi was closely related to C. canis and C. felis. The identifications provided by diagnostic laboratories of the specific parasite species present in a sample showed poor agreement with their identifications based on genotyping obtained in this study. Molecular techniques appear to be essential for determining the specific coccidial species responsible for individual and group outbreaks of coccidiosis and for further understanding of eimeriid host-parasite relationships.

Cystoisospora suis merozoite development assay for screening of drug efficacy in vitro

Cystoisospora suis is a common diarrheal pathogen of piglets and typically controlled by metaphylactic toltrazuril application. Recently, toltrazuril resistance has been reported in the field; however, both evaluation of toltrazuril efficacy against field isolates and the anticoccidial drug development for pigs is hampered by costs and labor of animal experimentation. Therefore an in vitro merozoite development assay was developed to evaluate the efficacy of compounds against C. suis in vitro. Monolayers of IPEC-1 cells were infected with sporozoites derived from oocysts of defined C. suis laboratory strains and the optimal infection dose as well as concentration, time point and duration of treatment were evaluated by quantitative real-time PCR. Cell cultures were treated with bumped kinase inhibitor (BKI) 1369 at different time points to evaluate the possibility to delineate effects on different developmental stages in vitro during invasion and early infection, and to determine different inhibitory concentrations (IC₅₀, IC₉₅). BKI 1369 had an IC₅₀ of 35 nM and an IC₉₅ of 350 nM. Dose- and duration-dependent efficacy was seen when developing stages were treated with BKI 1369 after infection (days 0-1, 2-3 and 2-5) but not when sporozoites were pre-incubated with BKI 1369 before infection. Efficacies of further BKIs were also evaluated at 200 nM. BKI 1318, 1708, 1748 and 1862 had an efficacy comparable to that of BKI 1369 (which is also effective in vivo). BKI 1862 showed a more pronounced loss of efficacy in lower concentrations than BKI 1369, signifying pharmacokinetic differences of similar compounds detectable in vitro. In addition, the effects of toltrazuril and its metabolites, toltrazuril sulfoxide and toltrazuril sulfone, on a toltrazuril sensitive and a resistant strain of C. suis were evaluated. Inhibition of merozoite growth in vitro by toltrazuril and its metabolites was dose-dependent only for toltrazuril. Clear differences were noted for the effect on a toltrazuril-sensitive vs. a resistant strain, indicating that this in vitro assay has the capacity to delineate susceptible from resistant strains in vitro. It could also be used to evaluate and compare the efficacy of novel compounds against C. suis and support the determination of the optimal time point of treatment in vivo.

A QPCR ASSAY AND TESTING GUIDELINES FOR THE MOLECULAR DIAGNOSIS OF SYSTEMIC ISOSPOROSIS (FORMERLY ATOXPLASMOSIS) IN PASSERINE BIRDS

Systemic isosporosis (formerly atoxoplasmosis), is a protozoal infection that causes death in nestling and fledgling passerine birds impacting ex situ breeding and reintroduction programs. Because current antemortem diagnostic tests lack sensitivity, a qPCR was developed for detection of Isospora spp. using primers and a fluorescent-tagged MGB probe targeting the large subunit (28s) ribosomal RNA gene (assay efficiency = >100%; sensitivity = <1 dsDNA copy). The assay was used to screen postmortem frozen or formalin-fixed paraffin-embedded tissue samples from passerine birds (n = 24; 12 with confirmed systemic isosporosis), whole blood and feces (n = 38) from live passerines, and other tissues infected with phylogenetically similar protozoa. The qPCR identified Isospora sp. DNA in tissues from 21/24 birds including 12/12 birds with cytologically-histologically confirmed infection (100% sensitivity) and 9/12 birds lacking microscopic organisms. The assay also amplified Eimeria sp. DNA; however, sequence analysis ruled out infection in the passerine cases. Blood and/or feces were positive in 30/38 birds, and in only 7/38 birds, blood and feces both contained Isospora sp. DNA. Finally, the qPCR was utilized to screen 30 consecutive daily fecal samples from live passerines (n = 20) to determine optimal sampling protocols. One or more of the daily fecal samples were positive in all 20 birds. In individual birds, the interval between positive qPCR amplification results ranged from 0 to 23 days, with an average of 5.85 days. Simulated application of 13 potential sample collection schedules was used to identify the sensitivity of repeated testing for identification of infected birds. Increased sampling days resulted in higher sensitivity but increased both cost and animal handling requirements. Based on statistical analysis and clinical considerations, the testing recommendation for detection of fecal shedding was collection and assay of five consecutive daily fecal samples, which had an average diagnostic sensitivity of 0.86.

Reduced treatment frequencies with bumped kinase inhibitor 1369 are effective against porcine cystoisosporosis

Bumped kinase inhibitors (BKIs) are a new class of antiprotozoal drugs that target calcium-dependent protein kinase 1 (CDPK1) in various apicomplexan parasites. A multiple dose regimen of BKI 1369 has been shown to be highly effective against Cystoisospora suis (syn. Isospora suis), the causative agent of neonatal porcine coccidiosis. However, multiple dosing may not be widely applicable in the field. The present study aimed to determine the efficacy of reduced treatment frequencies with BKI 1369 against porcine cystoisosporosis in vitro and in vivo. Pre-incubation of sporozoites with BKI 1369 completely failed to inhibit the infection in vitro unless treatment was prolonged post-infection. Notably, a single treatment of infected cell cultures 2 days post-infection (dpi) resulted in a significant reduction of merozoite replication. In an experimental infection model, treatment of suckling piglets experimentally infected with C. suis 2 and 4 dpi with 20 mg BKI 1369/kg body weight completely suppressed oocyst excretion. A single treatment on the day of infection or 2 dpi suppressed oocyst excretion in 50% and 82% of the piglets and reduced the quantitative excretion in those that shed oocysts by 95.2% and 98.4%, respectively. Moreover, a significant increase in body weight gain and reduced number of diarrhea days were observed in BKI 1369 treated piglets compared to the control piglets, irrespective of time points and frequencies of treatment. Given that reduced treatment frequencies with BKI 1369 are comparable in efficacy to repeated applications without any adverse effects, this could be considered as a practical therapeutic alternative against porcine cystoisosporosis.

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BKI 1369 does not target host cell invasion by C. suis sporozoites but replication of merozoites.

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Single treatment with BKI 1369 in parallel with experimental infection is not effective for the control of cystoisosporosis.

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Two doses of BKI 1369 at 2 and 4 dpi completely suppressed oocyst excretion in piglets experimentally infected with C. suis.

Morphological and molecular characterization of Cystoisospora laidlawi oocysts (Apicomplexa: Eimeriidae) in farmed American mink (Neovison vison) in Denmark

From a longitudinal survey conducted on 30 Danish mink farms in 2016, 11.0% of faecal samples (456/4140) were positive for Cystoisospora laidlawi oocysts by microscopy, with 60% (189/315) of mink being positive at least once during the study period. Morphological analysis of sporulated oocysts identified Cystoisospora oocysts measuring 34.3 × 29.5 μm with an oocyst length/width (L/W) ratio of 1.2. The morphological features of the oocysts were identical to Isospora laidlawi previously morphological identified in farmed mink from Denmark and elsewhere. Phylogenetic analysis of 18S rDNA sequences (1221 bp) from three positive mink indicated that Cystoisospora from mink shared the highest genetic similarity to C. canis from a Canadian dog (99.6%). The phylogenetic analysis placed Cystoisospora from mink in a clade with other Cystoisospora isolates.

Clinical and Pathological Aspects of Systemic Isospora Infection in Blue-crowned Laughing Thrushes (Garrulax courtoisi) at Jersey Zoo

Based on a review of species mortalities, systemic Isospora species was identified as the primary cause of death in 22% (19 of 87) of blue-crowned laughing thrushes (BCLTs; Garrulax courtoisi) at the Jersey Zoo between 1997 and 2016. Fifty-eight percent of the affected birds were between 1 and 2 years old, and in 89% of cases, death occurred between August and December. Abnormal clinical findings in BCLTs with Isospora species infections included hepatomegaly and pectoral muscle myositis in 79% of the cases. The results of diagnostic blood testing in 90% of infected BCLTs 30 days before death were consistent with a severe leukocytosis with greater than 20% of mononuclear cells infected by merozoites. The most common lesions identified during gross necropsy examination were splenomegaly (100%), hepatomegaly (95%), and multifocal, raised, white foci in pectoral (84%) and heart (79%) muscle. Lymphohistiocytic inflammation was identified in the liver, heart, spleen, lung, striated muscle, and kidney tissue of birds with positive results for Isospora species. Merozoites were often observed in spleen, liver, pectoral muscle, and hearts of infected BCLTs. Polymerase chain reaction diagnostic testing that targeted the cytochrome c oxidase subunit, followed by Sanger sequencing, was used to confirm Isospora species in all 14 birds tested. Of samples tested, the highest genetic correlation was with GenBank accession number KT203397 (Isospora species JRB-2016 mitochondrion).

Shifts in the Fecal Microbial Community of Cystoisospora suis Infected Piglets in Response to Toltrazuril

The protozoan parasite Cystoisospora suis causes diarrhea and reduced weight gain in suckling piglets. Infections occur in the first days of life; it is transient but can lead to dysbiosis, exacerbating disease and increasing mortality. Cystoisosporosis is effectively controlled by toltrazuril treatment; however, alterations of the gut microbial composition upon infection and treatment have not been investigated. This study evaluated the development of fecal microbiota of C. suis infected piglets in response to treatment with toltrazuril. Thirty-eight conventional piglets were infected with C. suis on the first day of life (dol 1). Twenty-six of them received either parenteral or oral toltrazuril 2 days later. Fecal samples were collected pre- and post-weaning (dol 1-15 and 31-38) for microbiota analysis using 16S rRNA amplicon sequencing and during dol 5-18 to determine fecal consistency and parasite excretion. All control animals shed parasites at least once and the majority developed diarrhea, while toltrazuril-treated piglets did not excrete parasites and only had low levels of diarrhea. Age-related shifts in the fecal microbiota composition and increase in diversity and species richness were seen until after weaning. Parasite infection disrupted bacterial maturation 2 weeks after infection. Irrespective of the route of administration, fecal communities of piglets in the treated groups clustered separately and were more diverse compared to that of control piglets during the acute phase of infection on dol 11. Control piglet feces showed higher levels of Fusobacteriaceae and Veillonellaceae, while Ruminococcaceae, Lachnospiraceae, S24-7, Clostridiaceae, and Erysipelotrichaceae were more abundant in feces of treated piglets on dol 11. Thereafter, treatment-related effects on the microbial communities were small and mainly detectable on dol 34 (5 days post-weaning), potentially indicating that the oral toltrazuril treatment might have had long-term effects on host physiological responses post-weaning. Irrespective of the administration route, toltrazuril prevented C. suis-related dysbiosis and maintained species richness and diversity on dol 11. In addition to cystoisosporosis prevention, toltrazuril seems to contribute to the stabilization of the gut microbial development during the suckling phase and thus may reduce the need for antibiotics to control infections with secondary bacterial enteropathogens in C. suis-infected suckling piglets.

Caryospora-Like Coccidia Infecting Green Turtles (Chelonia mydas): An Emerging Disease With Evidence of Interoceanic Dissemination

Protozoa morphologically consistent with Caryospora sp. are one of the few pathogens associated with episodic mass mortality events involving free-ranging sea turtles. Parasitism of green turtles (Chelonia mydas) by these coccidia and associated mortality was first reported in maricultured turtles in the Caribbean during the 1970s. Years later, epizootics affecting wild green turtles in Australia occurred in 1991 and 2014. The first clinical cases of Caryospora-like infections reported elsewhere in free-ranging turtles were from the southeastern US in 2012. Following these initial individual cases in this region, we documented an epizootic and mass mortality of green turtles along the Atlantic coast of southern Florida from November 2014 through April 2015 and continued to detect additional, sporadic cases in the southeastern US in subsequent years. No cases of coccidial disease were recorded in the southeastern US prior to 2012 despite clinical evaluation and necropsy of stranded sea turtles in this region since the 1980s, suggesting that the frequency of clinical coccidiosis has increased here. Moreover, we also recorded the first stranding associated with infection by a Caryospora-like organism in Hawai'i in 2018. To further characterize the coccidia, we sequenced part of the 18S ribosomal and mitochondrial cytochrome oxidase I genes of coccidia collected from 62 green turtles found in the southeastern US and from one green turtle found in Hawai'i. We also sequenced the ribosomal internal transcribed spacer regions from selected cases and compared all results with those obtained from Caryospora-like coccidia collected from green turtles found in Australia. Eight distinct genotypes were represented in green turtles from the southeastern US. One genotype predominated and was identical to that of coccidia collected from the green turtle found in Hawai'i. We also found a coccidian genotype in green turtles from Florida and Australia with identical 18S and mitochondrial sequences, and only slight inter-regional differences in the internal transcribed spacer 2. We found no evidence of geographical structuring based on phylogenetic analysis. Low genetic variability among the coccidia found in green turtle populations with minimal natural connectivity suggests recent interoceanic dissemination of these parasites, which could pose a risk to sea turtle populations.

Cystoisospora belli infections in humans: the past 100 years

Cystoisospora belli is a coccidian parasite of humans, with a direct fecal-oral transmission cycle. It is globally distributed, but mainly found in tropical and subtropical areas. Many cases of C. belli infections have been reported in patients with HIV, and in patients undergoing immunosuppressive therapy for organ transplants or those treated for tumours worldwide. Unsporulated or partially sporulated oocysts of C. belli are excreted in feces. When sporulated oocysts in contaminated water or food are ingested, asexual and sexual stages of C. belli are confined to the epithelium of intestines, bile ducts and gallbladder. Monozoic tissue cysts are present in extra-intestinal organs (lamina propria of the small and large intestine, lymph nodes, spleen, and liver) of immunosuppressed humans. However, a paratenic host has not been demonstrated. Cystoisospora belli infections can be persistent, lasting for months, and relapses are common; the mechanism of relapse is unknown. Recently, the endogenous stages of C. belli were re-examined and attention was drawn to cases of misidentification of non-protozoal structures in the gallbladder of patients as C. belli. Here, we review all aspects of the biology of C. belli, including morphology, endogenous stages, prevalence, epidemiology, symptoms, diagnosis and control.

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

Using a combination of morphological and molecular data, we describe a new apicomplexan parasite, Isospora svecica sp. n., from the white-spotted bluethroat, Luscinia svecica cyanecula, from the Czech Republic. Oocysts were found in its intestinal tract. Sporulation was exogenous and took 1-3 days. The oocysts were slightly ellipsoidal, of average size 26.17 × 20.33 μm, with a smooth bilayered wall. Micropyle, oocyst residuum, and polar granules were absent. Sporocysts were bottle-shaped, of an average size of 18.82 × 8.82 μm, with a thin, colourless wall. A conspicuous knob-like Stieda body was present. Substieda body was barely visible. Sporocyst residuum was present in the form of granules of various sizes. Sporozoites were banana-shaped and contained large anterior and small posterior refractile bodies. Partial DNA sequences of three genes were obtained from oocysts of Isospora svecica sp. n., being most closely related to other isosporans described from passerines. Little is known about the parasites of the avian family Muscicapidae, including coccidia, a highly prevalent parasitic protist group in all vertebrate classes. Only six species of the genus Isospora have so far been described in Muscicapidae, together with several "Isospora sp." that in fact most likely represent Isospora lacazei. The newly described Isospora svecica sp. n. differs morphologically from other coccidia reported from muscicapid birds, and represents the first coccidian species described from Luscinia svecica.

Avian malaria-mediated population decline of a widespread iconic bird species

Parasites have the capacity to affect animal populations by modifying host survival, and it is increasingly recognized that infectious disease can negatively impact biodiversity. Populations of the house sparrow (Passer domesticus) have declined in many European towns and cities, but the causes of these declines remain unclear. We investigated associations between parasite infection and house sparrow demography across suburban London where sparrow abundance has declined by 71% since 1995. Plasmodium relictum infection was found at higher prevalences (averaging 74%) in suburban London house sparrows than previously recorded in any wild bird population in Northern Europe. Survival rates of juvenile and adult sparrows and population growth rate were negatively related to Plasmodium relictum infection intensity. Other parasites were much less prevalent and exhibited no relationship with sparrow survival and no negative relationship with population growth. Low rates of co-infection suggested sparrows were not immunocompromised. Our findings indicate that P. relictum infection may be influencing house sparrow population dynamics in suburban areas. The demographic sensitivity of the house sparrow to P. relictum infection in London might reflect a recent increase in exposure to this parasite.

Endogenous development of Cystoisospora belli in intestinal and biliary epithelium of humans

Cystoisospora(Isospora)belliis a coccidian parasite of humans. It can cause serious digestive disorders involving infection of intestines, biliary tract and gallbladder, especially in those with depressed immunity. It has a direct fecal–oral transmission cycle. After ingestion of sporulated oocysts, the parasite multiplies asexually and sexually within host epithelial cells, resulting in unsporulated oocysts that are excreted in feces. The details of asexual and sexual stages are not known and certain inclusions in epithelial cells in biopsy samples have been erroneously identified recently asC. belli. Here, we provide details of developmental stages ofC. belliin two patients, in duodenal biopsy of one and biliary epithelium of the other. Immature and mature asexual stages (schizonts/meronts) were seen in epithelial cells. The merozoites were seen singly, in pairs and in groups in single parasitophorous vacuole (pv) in host cytoplasm. Immature and mature meronts were seen together in the same pv; up to eight nuclei were seen in meronts that retained elongated crescent shape; round multinucleated schizonts, seen in other coccidians, were not found. Meronts were up to 25µm long and contained up to ten merozoites that were 8–11µm long. The merozoites and meronts contained PAS-positive granules. Microgamonts (male) contained up to 30 nuclei that were arranged at the periphery and had condensed chromatin; 1–3 PAS-positive, eosinophilic, residual bodies were left when microgametes were formed. The microgametes were 4µm long and PAS-negative. All stages of macrogamonts, including oocysts were PAS-positive. The detailed description of the life cycle stages ofC. bellireported here should facilitate in histopathologic diagnosis of this parasite.

Re-evaluation of merogony of a Cystoisospora ohioensis-like coccidian and its distinction from gametogony in the intestine of a naturally infected dog

Four species of Cystoisospora, C. canis, C. ohioensis, C. neorivolta and C. burrowsi are described from feces of dogs. Of these, the oocysts of C. canis are the largest and easily distinguished from the remaining three species. Oocysts of C. ohioensis, C. neorivolta and C. burrowsi are difficult to distinguish because of overlap in their sizes. However, based on endogenous developmental stages, C. ohioensis is distinct from C. neorivolta and C. burrowsi because its endogenous stages are confined to surface epithelium of intestine whereas endogenous stages of C. neorivolta and C. burrowsi are predominantly in the lamina propria. There are uncertainties regarding the endogenous stages of C. neorivolta and C. burrowsi and there is no way now to determine whether C. burrowsi and C. neorivolta are different parasites; therefore, these are referred as C. ohioensis-like organisms. Additionally, mode of division of asexual stages of coccidia of dogs is largely unknown and ultrastructural studies are lacking. In the present study, development of asexual and sexual stages of a C. ohioensis-like organism in a naturally infected dog is described by light microscopy and by transmission electron microscopy. Merozoites divided by endodyogeny/merogony. Meronts were crescent/merozoite-shaped and contained a maximum of eight nuclei. A distinctive feature of merozoites was the presence of many PAS-positive amylopectin granules that were absent or rare in immature microgamonts making it possible to distinguish them.

A review of Cystoisospora felis and C. rivolta-induced coccidiosis in cats

Until the discovery of Toxoplasma gondii oocysts in cat feces in 1970, little was known of coccidiosis in cats. Until 1970, three coccidian parasites based on different sized oocysts were recognized, the parasite with large oocysts (∼40 μm long and called Isospora felis), medium sized oocysts (∼25 μm long, called Isospora rivolta), and small sized oocysts (14 μm or less, called Isospora bigemina) were known and they were considered not host-specific. Later, it was demonstrated that these parasites were host-specific and had also extra-intestinal stages. The Isospora bigemina turned out to be more than 25 organisms belonging to T. gondii, Hammondia spp., Sarcocystis spp., Besnoitia spp., and Neospora spp.; these subjects have been reviewed previously in detail. The present paper summarizes biology of Isospora felis, and I. rivolta (now transferred to genus Cystoisospora), including taxonomy, life cycle, diagnosis, and treatment. Re-excretion of T. gondii oocysts from chronically infected cats after superinfection with Cystoisospora felis oocysts is discussed. There are only two species of Cystoisospora species in cats, C. felis and C. rivolta; Isospora novocati and Cystoisospora frenkeli named for I. rivolta-like parasites of cats are considered synonym of C. rivolta. Clinical coccidiosis occurs more commonly in recently weaned kittens and C. felis infections are more prevalent than C. rivolta.

A review of coccidiosis in Old World camels

Domesticated Old World camels (Camelus dromedarius and C. bactrianus) are important for the economy of several countries in Asia, Africa, and the Arabian Peninsula, and coccidiosis is important as a cause of mortality in juvenile camels. There is confusion concerning the species of coccidian parasites in camels and their life cycles. The objective of the present paper is to review biology of the Eimeria and Cystoisospora species in camels. The following conclusions were drawn. Although five species of Eimeria; E. cameli, E. rajasthani, E. dromedarii, E. bactriani, and E. pellerdyi were named from camels, only E. cameli, E. rajasthani, E. dromedarii have been consistently found in numerous surveys and they are morphologically distinct. We consider E. pellerdyi and E. bacterini as species enquirende/ not valid. E. cameli oocysts are distinctive, dark brown and up to 108 μm long. Its gametogonic stages and oocysts are present in the lamina propria of small intestines; only sexual stages have been confirmed. The remaining species of Eimeria (E. rajasthani and E. dromedarii) in camels are <40 μm long and their endogenous stages are unknown. There is one valid species of Cystoisospora, C. orlovi in camels and is associated with severe disease in young camels, both pastoral and stall fed camels. Camels as young as nine days old can develop severe diarrhea and can die before oocysts are detected in feces. Lesions and endogenous stages are confined to the large intestine. The main lesion is hemorrhagic, diphtheroid to hemorrhagic colitis-associated with sexual stages; asexual stages are unknown. Oocysts are rarely excreted by adult camels, and in low numbers. Therefore, infection in very young camels remains unexplained.

Morphological and molecular characterization of Cystoisospora sp. from Asian small-clawed otters Aonyx cinereus

In this study, we provide the first description of Cystoisospora infection in Asian small-clawed otters (Aonyx cinereus). In July 2017, three juvenile otters recently imported from the Republic of Indonesia showed severe diarrhea and were diagnosed with coccidial infection; two of them eventually died. Fecal examination revealed the presence of numerous oocysts. Sporulated oocysts showed typical Cystoisospora features, measuring 24.6 ± 1.6 (22.0–27.0) × 21.8 ± 1.4 (19.0–25.0) μm, with an oocyst length/width ratio of 1.1 ± 0.1 (1.0–1.3). Each sporocyst contained four sporozoites in a head-to-tail arrangement. The Stieda body was absent, and the sporocyst residuum was present. These morphological characteristics differentiated this species from the other valid Cystoisospora species described from mustelids. Molecular analysis was conducted at two loci: the nuclear 18S ribosomal RNA and mitochondrial cytochrome c oxidase subunit I genes. The 18S sequence showed high similarity with canine Cystoisispora ohioensis (1-bp difference, 1422/1423 [99.9%]). At the cytochrome c oxidase subunit I gene locus, the sequence from otters was identical to that of feline Cystoisospora rivolta (847/847 [100%]). Phylogenetic analyses using concatenated data demonstrated that Cystoisospora sp. from otters and C. rivolta grouped together in the same Cystoisospora clade. Based on these data, we concluded that Cystoisospora sp. detected from otters appeared to be highly similar to C. rivolta.

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We characterized Cystoisospora infection in three Asian small-clawed otters.

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Two otters showed anorexia, green diarrhea, and vomiting.

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Fecal examination revealed numerous oocysts with typical Cystoisospora features.

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Sporulated oocysts were morphologically differentiated from those of other Cystoisospora spp. from mustelids.

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Molecular and morphological features were highly similar to feline C. rivolta.

Pathological and molecular characterization of systemic isosporosis (atoxoplasmosis) in captive green-winged saltator (Saltator similis)

Systemic isosporosis, also called atoxoplasmosis or visceral coccidiosis, is a disease that affects birds in general. Pathogenesis of systemic isosporosis and its etiologic agent have not been well characterized, but taxonomically Atoxoplasma is currently considered a junior objective synonym of Isospora. The present report aimed to describe pathological and molecular findings of systemic isosporosis in captive green-winged saltators (Saltator similis) from the State of Espírito Santo, Brazil. In a commercial breeding facility eleven birds with two to nine months of age died from 2015 to 2016. These birds developed nonspecific clinical signs, including bristly feathers, hyporexia, loss of weight, and apathy. Two birds were necropsied, and grossly there were hepatomegaly, splenomegaly, necrosis of lymphoid follicles, hepatic necrosis, and severe enteritis. Merozoites were observed in the heart, small intestine, proventriculus, brain, liver, spleen, and kidneys. 23 S RNA PCR amplicons from DNA extracted from the liver and the intestinal contents had 99% identity with Atoxoplasma sp., whereas amplicons of mitochondrial cytochrome c oxidase subunit 1 ha d 97% identity with Isospora greineri. In conclusion, this report indicates that systemic isosporosis in green-winged saltator is a disease that affects the spleen, liver, and small intestine, with high mortality for young birds, resulting in significant loses to commercial breeding facilities.

A new species of Cystoisospora Frenkel, 1977 (Apicomplexa: Sarcocystidae) from Oecomys mamorae Thomas (Rodentia: Cricetidae) in the Brazilian Pantanal

Despite the great diversity of coccidians, to our knowledge, no coccidian infections have been described in Oecomys spp. In this context, we examined Oecomys mamorae Thomas (Rodentia: Cricetidae) from the Brazilian Pantanal for infections with enteric coccidia. Nine individuals were sampled, and one was found to be infected. The oöcysts were recovered through centrifugal flotation in sugar solution. Using morphological and morphometric features, we described a new species of Cystoisospora Frenkel, 1977. Sporulated oöcysts were ovoidal 20.0-29.1 × 16.4-23.2 (26.7 × 21.2) µm and contained two sporocysts, 12.9-19.1 × 9.4-13.9 (16.4 × 12.4) µm, each with four banana-shaped sporozoites. Polar granule and oöcyst residuum were both absent. We documented the developmental forms in the small intestine and described the histopathological lesions in the enteric tract. Our results indicate that the prevalence of Cystoisospora mamorae n. sp. in O. mamorae is low, and tissue damage in the enteric tract is mild, even in the presence of coccidian developmental stages.

Urban Dog Parks as Sources of Canine Parasites: Contamination Rates and Pet Owner Behaviours in Lisbon, Portugal

Dog parks represent a recent trend in western countries, enabling owners to spend quality time with their pets in a controlled environment. Despite their growing popularity, few studies have been performed to date on these parks to investigate dog intestinal parasitic infections and soil contamination. The present study examined 369 faecal and 18 soil samples collected from 3 dog parks in Greater Lisbon, Portugal. Additionally, 102 interviews were performed with dog owners to assess dog-walking behaviours and parasite risk. In total, 33% of the faecal dog samples were infected with at least one parasitic agent: hookworms (16.5%), Cryptosporidium spp. (11.9%), Giardia spp. (11.4%), Toxascaris leonina (1.1%), Cystoisospora spp. (1.1%), Toxocara spp. (0.5%), and Sarcocystis sp. (0.3%). The soil of all the parks was contaminated with hookworm eggs. This is the first study performed in a European urban area to assess canine faecal contamination and parasitic agents in dog parks. Our results highlight the potential of these parks as a source of transmission for canine parasites, including some with zoonotic potential. Public awareness and effective preventive measures should be promoted to minimise the health-risk impact to both animals and humans, under the scope of environmental and public health.

Isospora lunaris n. sp. (Apicomplexa: Eimeriidae) from the domestic Java sparrow in Japan

Five individuals of the domestic Java sparrows, Lonchura oryzivora (Aves: Estrildidae), were examined for coccidian parasites. Sporulated oocysts had two sporocysts containing four sporozoites each. Sporulated oocysts (n=30) were spherical, with a two splinter-like polar granules. Oocyst size was 22.1×20.7 (20.0-25.0×20.0-22.5)μm. They had a thick wall that consisted of a pale yellow outer layer and a dark yellow inner layer, and lacked micropyle and residuum. Sporocysts (n=60) were elongated ovoid 14.1×9.8 (12.5-15.0×7.5-10.0)μm, smooth walled, and colorless, with crescent-shaped Stieda and indistinct substieda bodies. Sporocyst residuum was interspersed between sporozoites. Sporozoites were oriented transverse to the sporocyst longitudinal axis. On the basis of morphological data, the species isolated in the present study is a new species of Isospora and propose the name Isospora lunaris n. sp.

Molecular testing for clinical diagnosis and epidemiological investigations of intestinal parasitic infections

Over the past few decades, nucleic acid-based methods have been developed for the diagnosis of intestinal parasitic infections. Advantages of nucleic acid-based methods are numerous; typically, these include increased sensitivity and specificity and simpler standardization of diagnostic procedures. DNA samples can also be stored and used for genetic characterization and molecular typing, providing a valuable tool for surveys and surveillance studies. A variety of technologies have been applied, and some specific and general pitfalls and limitations have been identified. This review provides an overview of the multitude of methods that have been reported for the detection of intestinal parasites and offers some guidance in applying these methods in the clinical laboratory and in epidemiological studies.

Molecular phylogenetic analyses of tissue coccidia (sarcocystidae; apicomplexa) based on nuclear 18s RDNA and mitochondrial COI sequences confirms the paraphyly of the genus Hammondia

Partial mitochondrial cytochromecoxidase subunit I (mt COI) sequences were generated from:Toxoplasma gondii(strains CTG, GTI, MAS, ME49, PTG, TgCatBr5, TgCat, Br64, TgCgCal, TgToucan);Neospora caninum(Strain NC1);Hammondia hammondi(Strain H.H–20);H. heydorni; H. cf.triffittae; Cystoisospora felis; C. suis; C. canis; C. rivolta; C. cf.ohioensis; Caryospora bigenetica; Sarcocystis rileyi; andS. neurona. Nuclear 18S rDNA sequences were generated forH. heydorni, H. hammondi, C. suis, C. canis, C. felis, C. rivolta, C. cf.ohioensis, S. neurona, andS. rileyi. Aligned, concatenated 18S rDNA and COI sequences were Bayesian analysed using partitioned nucleotide substitution models [HKY + I + G for 18S; GTR + I + G codon (code = metmt) for COI]. Phylogenetic hypotheses supported a monophyletic Sarcocystidae and its subfamilie with two major clades within the Toxoplasmatinae: (1) a monophyletic clade ofCystoisosporaspp. withNephroisospora eptesici; and (2) a clade ofToxoplasma, NeosporaandHammondia. Within the latter,Hammondiawas shown to be paraphyletic;H. heydorniandH. triffittaewere monophyletic withN. caninum[canine definitive hosts (DHs)], whereasH. hammondiwas monophyletic withT. gondii(feline DHs). A new genus is erected to resolve the paraphyly of the genusHammondiaconfirmed using mt COI and combined 18S/COI sequence datasets.

Detection and characterization of diverse coccidian protozoa shed by California sea lions

Tissue-cyst forming coccidia in the family Sarcocystidae are etiologic agents of protozoal encephalitis in marine mammals including the federally listed Southern sea otter (Enhydra lutris). California sea lions (Zalophus californianus), whose coastal habitat overlaps with sea otters, are definitive hosts for coccidian protozoa provisionally named Coccidia A, B and C. While Coccidia A and B have unknown clinical effects on aquatic wildlife hosts, Coccidia C is associated with severe protozoal disease in harbor seals (Phoca vitulina). In this study, we conducted surveillance for protozoal infection and fecal shedding in hospitalized and free-ranging California sea lions on the Pacific Coast and examined oocyst morphology and phenotypic characteristics of isolates via mouse bioassay and cell culture. Coccidia A and B were shed in similar frequency, particularly by yearlings. Oocysts shed by one free-ranging sea lion sampled at Año Nuevo State Park in California were previously unidentified in sea lions and were most similar to coccidia infecting Guadalupe fur seals (Arctocephalus townsendi) diagnosed with protozoal disease in Oregon (USA). Sporulated Coccidia A and B oocysts did not replicate in three strains of mice or in African green monkey kidney cells. However, cultivation experiments revealed that the inoculum of fecally-derived Coccidia A and B oocysts additionally contained organisms with genetic and antigenic similarity to Sarcocystis neurona; despite the absence of detectable free sporocysts in fecal samples by microscopic examination. In addition to the further characterization of Coccidia A and B in free-ranging and hospitalized sea lions, these results provide evidence of a new role for sea lions as putative mechanical vectors of S. neurona, or S. neurona-like species. Future work is needed to clarify the distribution, taxonomical status, and pathogenesis of these parasites in sea lions and other marine mammals that share their the near-shore marine environment.

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Diverse coccidian protozoa shed by California sea lions (CSL) were characterized.

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Oocyst shedding patterns, taxonomy, morphology and pathogenicity were examined.

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Mice and cell cultures were not susceptible to Coccidia A or B of CSL origin.

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Sarcocystis neurona-like zoites grew in cells inoculated with CSL fecal samples.

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California sea lions may serve as mechanical vectors of an S. neurona-like organism.

Molecular phylogenetics of eimeriid coccidia (Eimeriidae, Eimeriorina, Apicomplexa, Alveolata): A preliminary multi-gene and multi-genome approach

Coccidia possess three distinct genomes: nuclear, mitochondrial, and plastid. Sequences from five genes located on these three genomes were used to reconstruct the phylogenetic relationships of members of the phylum Apicomplexa: 18S rDNA sequences from the nuclear (nu) genome, partial cytochrome c oxidase subunit I sequences from the mitochondrial (mt) genome, and partial 16S and 23S rDNA sequences and RNA polymerase B sequences from plastid (pl) genomes. Maximum parsimony, maximum likelihood, and Bayesian inference were used in conjunction with nuclear substitution models generated from data subsets in the analyses. Major groups within the Apicomplexa were well supported with the mitochondrial, nuclear, and a combination of mitochondrial, nuclear and concatenated plastid gene sequences. However, the genus Eimeria was paraphyletic in phylogenetic trees based on the nuclear gene. Analyses using the individual genes (18S rDNA and cytochrome c oxidase subunit I) resolved the various apicomplexan groups with high Bayesian posterior probabilities. The multi-gene, multi-genome analyses based on concatenated nu 18S rDNA, pl 16S, pl 23S, pl rPoB, pl rPoB1, and mt COI sequences appeared useful in resolving phylogenetic relationships within the phylum Apicomplexa. Genus-level relationships, or higher, appear best supported by 18S rDNA analyses, and species-level analyses are best investigated using mt COI sequences; for parasites for which both loci are available, nuclear 18S rDNA sequences combined with mitochondrial COI sequences provide a compact and informative molecular dataset for inferring the evolutionary relationships taxa in the Apicomplexa.