Dynamically expressed genes provide candidate viability biomarkers in a model coccidian.

Eimeria parasites cause enteric disease in livestock and the closely related Cyclospora cayetanensis causes human disease. Oocysts of these coccidian parasites undergo maturation (sporulation) before becoming infectious. Here, we assessed transcription in maturing oocysts of Eimeria acervulina, a widespread chicken parasite, predicted gene functions, and determined which of these genes also occur in C. cayetanensis. RNA-Sequencing yielded ~2 billion paired-end reads, 92% of which mapped to the E. acervulina genome. The ~6,900 annotated genes underwent temporally-coordinated patterns of gene expression. Fifty-three genes each contributed >1,000 transcripts per million (TPM) throughout the study interval, including cation-transporting ATPases, an oocyst wall protein, a palmitoyltransferase, membrane proteins, and hypothetical proteins. These genes were enriched for 285 gene ontology (GO) terms and 13 genes were ascribed to 17 KEGG pathways, defining housekeeping processes and functions important throughout sporulation. Expression differed in mature and immature oocysts for 40% (2,928) of all genes; of these, nearly two-thirds (1,843) increased their expression over time. Eight genes expressed most in immature oocysts, encoding proteins promoting oocyst maturation and development, were assigned to 37 GO terms and 5 KEGG pathways. Fifty-six genes underwent significant upregulation in mature oocysts, each contributing at least 1,000 TPM. Of these, 40 were annotated by 215 GO assignments and 9 were associated with 18 KEGG pathways, encoding products involved in respiration, carbon fixation, energy utilization, invasion, motility, and stress and detoxification responses. Sporulation orchestrates coordinated changes in the expression of many genes, most especially those governing metabolic activity. Establishing the long-term fate of these transcripts in sporulated oocysts and in senescent and deceased oocysts will further elucidate the biology of coccidian development, and may provide tools to assay infectiousness of parasite cohorts. Moreover, because many of these genes have homologues in C. cayetanensis, they may prove useful as biomarkers for risk.

Recent achievements and doors opened for coccidian parasite research and development through transcriptomics of enteric sexual stages.

The Coccidia is the largest group of parasites within the Apicomplexa, a phylum of unicellular, obligate parasites characterized by the possession of an apical complex of organelles and structures in the asexual stages of their life cycles, as well as by a sexual reproductive phase that occurs enterically in host animals. Coccidian sexual reproduction involves morphologically distinct microgametes and macrogametes that combine to form a diploid zygote and, ultimately, following meiosis and mitosis, haploid, infectious sporozoites, inside sporocysts within an oocyst. Recent transcriptomic analyses have identified genes involved in coccidian sexual stage development and reproduction, including genes encoding for microgamete- and macrogamete-specific proteins with roles in gamete motility, fusion and fertilization, and in the formation of the resilient oocyst wall that allows coccidians to persist for long periods in the environment. Transcriptomics has also provided important clues about the regulation of gene expression in the transformation of parasites from one developmental stage to the next, a complex sequence of events that may involve transcription factors such as the apicomplexan Apetala2 (ApiAP2) family, alternative splicing, regulatory RNAs and MORC (a microrchida homologue and regulator of sexual stage development in Toxoplasma gondii). The molecular dissection of coccidian sexual development and reproduction by transcriptomic analyses may lead to the development of novel transmission-blocking strategies.

Effect of Homeopathic Medicines on Intestinal Coccidia and Immune Response Cells in Spotted Rose Snapper (Lutjanus guttatus).

BACKGROUND: Homeopathy has been widely applied in freshwater species but rarely in marine fish. Farm stress destabilises host-pathogen equilibrium, favouring parasites and disease. Coccidian endoparasites cause intestinal infections and cell degeneration. MATERIALS AND METHODS: Naturally parasite-infested juvenile snapper Lutjanus guttatus (n = 430; weight 1.9 ± 0.01 g; length 4.9 ± 0.03 cm) specimens were distributed in group sizes of 43, in 10 fiberglass tanks (100 L) with aeration and continuous water change. Five groups in duplicate were assessed: Passival (PaV); Passival and Phosphoricum acid Similia (PaV-PhA); Passival and Silicea terra Similia (PaV-SiT); Endecto and Infecçoes (End-Inf) and a control (Ethanol) for 45 days. Feed was sprinkled with treatment (5% v/w) and dried to avoid ethanol side-effects. Statistical results were expressed as mean ± standard error of the mean. RESULTS: Intestinal coccidia were recorded histopathologically, with the least incidence attained at T45 with End-Inf treatment (p < 0.001), coinciding with the highest lymphocyte (p = 0.015) count. Fish treated with PaV-PhA recorded a higher percentage of neutrophils (p = 0.015), and those treated with PaV-PhA, PaV-SiT and End-Inf revealed a decrease in lesions, degree of alteration and change in intestine and stomach tissues (p < 0.05). The number of mucous cells in gills was greater (p < 0.001) for End-Inf (43 ± 0.58), PaV-SiT (40 ± 2.89) and PaV-PhA (39 ± 3.46) as compared respectively with T0 and control (19 ± 0.58 and 28 ± 2.31). PaV and PaV-SiT increased carbohydrate reserves in liver (28.4 ± 1.39% and 22.4 ± 0.12%, respectively) compared with T0 and control (3.4 ± 0.32 and 5.6 ± 0.66%). The highest survival rate was 97.7 ± 0.16% in fish treated with PaV and End-Inf. CONCLUSION: Homeopathic treatments had a positive effect on fish health. Besides the accumulation of metabolic reserves in the liver, homeopathic treatment was associated with mucin increase in gills as well as raised production of lymphocytes and neutrophils in blood, which could act as macrophages against intestinal coccidia.

Targeting of the mitochondrion by dinuclear thiolato-bridged arene ruthenium complexes in cancer cells and in the apicomplexan parasite Neospora caninum.

A library of 18 dinuclear-thiolato bridged arene ruthenium complexes, some of which with demonstrated activity against cancer cells, was screened for activity against a transgenic Neospora caninum strain that constitutively expresses beta-galactosidase. Initial assessments were done at concentrations of 2500, 250, 25 and 2.5 nM, and 5 compounds were further evaluated with regard to their half maximal proliferation-inhibiting concentration (IC50). Among those, [(η6-p-MeC6H4Pri)2Ru2(µ2-SC6H4-p-CH3)3]Cl (1), [(η6-p-MeC6H4Pri)2Ru2(µ2-SC6H4-p-But)3]Cl (2) and [(η6-p-MeC6H4Pri)2Ru2(µ2-SCH2C6H4-p-But)2(µ2-SC6H4-p-OH)]BF4 (9) inhibited N. caninum proliferation with low C50 values of 15, 5 and 1 nM, respectively, while [(η6-p-MeC6H4Pri)2Ru2(µ2-SC6H4-p-OH)3]Cl (3) and [(η6-p-MeC6H4Pri)2Ru2(µ2-SC6H4-p-mco)3]Cl (5, mco = 4-methylcoumarinyl) were less active (IC50 = 280 and 108 nM, respectively). These compounds did not affect human foreskin fibroblast (HFF) host cells at dosages of 5 µM and above, but impaired proliferation of the human ovarian carcinoma cell line A2780 (IC50 values of 130 nM (1), 30 nM (2), 530 nM (3), 7730 nM (5), 130 nM (9)). A2780 cancer cells were treated with complexes 1, 2, and 5, and biodistribution analysis using inductively coupled plasma mass spectrometry (ICP-MS) showed that most of the drugs accumulated in the mitochondrial fractions. Transmission electron microscopy showed that the parasite mitochondrion is the primary target also in N. caninum tachyzoites, but these compounds, when applied at 200 nM for 15 days in vitro, did not act parasiticidal. Complexes 1, 2 and 9 applied orally at 2 and 10 mg kg-1 day-1 during 5 days in a neosporosis mouse model did not reduce parasite load and did not limit parasite dissemination to the central nervous system. In accordance with these results, ICP-MS carried out on different organs of mice orally administrated with complexes 1 and 9, demonstrated that the drugs were readily absorbed, and after 3 and 48 h, were mainly detected in liver and kidney, but were largely absent from the brain. Thus, dinuclear thiolato-bridged arene ruthenium complexes exhibit interesting activities against N. caninum in vitro, but further modifications of these promising molecules are required to improve their bioavailability and pharmacokinetic properties in order to exert a pronounced and selective effect against N. caninum in vivo.

The state of art of neutrophil extracellular traps in protozoan and helminthic infections.

Neutrophil extracellular traps (NETs) are DNA fibers associated with histones, enzymes from neutrophil granules and anti-microbial peptides. NETs are released in a process denominated NETosis, which involves sequential steps that culminate with the DNA extrusion. NETosis has been described as a new mechanism of innate immunity related to defense against different pathogens. The initial studies of NETs were carried out with bacteria and fungi, but currently a large variety of microorganisms capable of inducing NETs have been described including protozoan and helminth parasites. Nevertheless, we have little knowledge about how NETosis process is carried out in response to the parasites, and about its implication in the resolution of this kind of disease. In the best case, the NETs entrap and kill parasites in vitro, but in others, immobilize the parasites without affecting their viability. Moreover, insufficient studies on the NETs in animal models of infections that would help to define their role, and the association of NETs with chronic inflammatory pathologies such as those occurring in several parasitic infections have left open the possibility of NETs contributing to pathology instead of protection. In this review, we focus on the reported mechanisms that lead to NET release by protozoan and helminth parasites and the evidence that support the role of NETosis in the resolution or pathogenesis of parasitic diseases.

Seasonal differences of corticosterone metabolite concentrations and parasite burden in northern bald ibis (Geronticus eremita): The role of affiliative interactions.

The reproductive season is energetically costly as revealed by elevated glucocorticoid concentrations, constrained immune functions and an increased risk of infections. Social allies and affiliative interactions may buffer physiological stress responses and thereby alleviate associated effects. In the present study, we investigated the seasonal differences of immune reactive corticosterone metabolite concentrations, endoparasite burden (nematode eggs and coccidian oocysts) and affiliative interactions in northern bald ibis (Geronticus eremita), a critically endangered bird. In total, 43 individually marked focal animals from a free-ranging colony were investigated. The analyses included a description of initiated and received affiliative interactions, pair bond status as well as seasonal patterns of hormone and endoparasite levels. During the reproductive season, droppings contained parasite eggs more often and corticosterone metabolite levels were higher as compared to the period after reproduction. The excretion rate of endoparasite products was lower in paired individuals than in unpaired ones, but paired animals exhibited higher corticosterone metabolite concentrations than unpaired individuals. Furthermore, paired individuals initiated affiliative behaviour more frequently than unpaired ones. This suggests that the reproductive season influences the excretion patterns of endoparasite products and corticosterone metabolites and that affiliative interactions between pair partners may positively affect endoparasite burden during periods of elevated glucocorticoid levels. Being embedded in a pair bond may have a positive impact on individual immune system and parasite resistance.

First detection of tick-borne pathogens of dogs from Malta.

The knowledge about the vector-borne infections in domestic dogs has been increasing worldwide. However no studies have been done on hard tick infestation and tick-borne pathogens (TBPs) of dogs present in Malta. Therefore, a total of 99 dogs was selected and inspected between March and July 2013 in 18 urban and 17 rural areas on the islands of Malta and Gozo. All ticks were removed from the dogs and identified. Blood samples were taken and tested for protozoa (Babesia spp. and Hepatozoon spp.) and bacteria (Anaplasma spp., Ehrlichia spp., Rickettsia spp.) by conventional PCR. All of the ticks collected from 34 (34.3%; 95% CI: 26-44) dogs belong to the species Rhipicephalus sanguineus sensu lato. Tick infestation on the farm dogs was significantly higher than that of dogs kept outdoors as pets (OR: 15.19, 95% CI: 2.72-118.92, p<0.001) or in a sanctuary (OR: 35.11, 95% CI: 3.20-1986.67, p<0.001). Altogether 22 animals were infected with one or two TBPs, most of them with Hepatozoon canis (16/22; 72.7%). Anaplasma platys and Babesia vogeli were detected in 5 and 4 dogs, respectively. Three dogs had co-infections caused by H. canis and A. platys. To the best of our knowledge, this is the first report on tick infestation and TBPs of dogs in Malta.

Canine tick-borne pathogens in Cyprus and a unique canine case of multiple co-infections.

Canine tick-borne pathogens such as Ehrlichia canis and Hepatozoon canis are widespread in the Mediterranean basin but have never been reported or investigated in Cyprus. We describe herein the presence of canine tick-borne pathogens in three dogs with clinical signs compatible with vector-borne diseases from Paphos area of Cyprus. Molecular and phylogenetic analysis revealed the presence of E. canis, Anaplasma platys, H. canis, Babesia vogeli and Mycoplasma haemocanis in Cyprus. One dog co-infected with E. canis, H. canis, B. vogeli and M. haemocanis is, to the best of our knowledge, the first report of this multiple co-infection in dogs. The tick-borne pathogens reported in the current study should be considered in the differential diagnoses in dogs exposed to ticks in Cyprus.

COCCIDIAL INFECTION OF THE ADRENAL GLANDS OF LEATHERBACK SEA TURTLES (DERMOCHELYS CORIACEA).

Histologic lesions incidental to the cause of death were observed in the adrenal glands of 17 subadult and adult leatherback sea turtles ( Dermochelys coriacea ) found dead or moribund on or near shore in North America. Round bodies, 250-300 µm in diameter composed of an outer capsule and large multinucleated cells surrounding a central mass of acellular material were distributed throughout the affected glands. Protozoal etiology was suspected based on some resemblance to coccidia; however, features diagnostic for coccidial infection were lacking in all but one case, which had a focal area of adrenalitis containing zoites. A novel eucoccidian partial 18S rRNA genetic sequence was consistently detected in adrenal glands with lesions. With the use of quantitative PCR, a specific area of the V4 region of the coccidian 18S gene was quantified in affected adrenal glands and correlated significantly with density of the histologic lesions. A second distinct, but closely related, 18S sequence was also amplified from the adrenal gland of one turtle and from a fecal sample containing unsporulated coccidian oocysts. The two 18S sequences identified from leatherback sea turtles form a clade within the family Eimeriidae. Further investigation is required to understand better the morphology of the life stages, life cycle, and potential effects of this coccidian parasite on adrenal function.

Molecular Characterization of Coccidia Associated with an Epizootic in Green Sea Turtles (Chelonia mydas) in South East Queensland, Australia.

In the spring of 2014, mass mortalities among wild green sea turtles occurred off the coast of south-east Queensland, Australia. The suspected causative agent was Caryospora cheloniae, an eimeriid coccidian implicated in previous epizootics. Necropsies were undertaken on a subset of 11 dead turtles, with subsequent histopathology and molecular analyses. All turtles returned positive PCR results for coccidial infection in various tissues; these included the brain, gastrointestinal tract, lung, kidney and thyroid. Granulomatous encephalitis was consistently observed, as well as enteritis and, less frequently, thyroiditis and nephritis. Sequencing and phylogenetic analyses indicated the presence of two distinct coccidian genotypes, presumably separate species-one associated with the brain, gastrointestinal tract and lung, and the second with the thyroid and kidney. Maximum likelihood and Bayesian inference analyses placed the first genotype closest to the lankesterellid genus Schellackia, rather than in the Eimeriidae, while the second was paraphyletic to the eimeriids. Presence of coccidial stages in extra-intestinal tissues of the primary host raises questions about the potential presence of intermediate or paratenic hosts within the life cycles, as well as their current placement relative to the genus Caryospora. This study represents the first genetic characterization of this emerging disease agent in green sea turtles, an endangered species, and has relevance for life-cycle elucidation and future development of diagnostics.

Caprine besnoitiosis: an emerging threat and its relationship to some other infections of ungulates by Besnoitia species.

Caprine besnoitiosis, caused by the cyst-forming protozoal apicomplexan Besnoitia caprae appears to be endemic in Kenya, Nigeria and Iran, but has yet to be detected in other parts of the world. The infection causes an important parasitic disease of goats in affected developing countries. Bovine besnoitiosis, is a widespread disease of cattle in Africa, Asia (but not Iran) and southern Europe. Recent epidemiological data confirm that the incidence and geographical range of bovine besnoitiosis in Europe is increasing, which is why growing attention has been given to the condition during the past decade. This paper reviews pertinent information on the biology, epidemiology, pathology, clinical signs, diagnosis and control of caprine besnoitiosis, together with its similarities to, and differences from, bovine besnoitiosis. The serious economic consequences of besnoitiosis on goat breeding and local meat and hide industries is also considered.

High feather corticosterone indicates better coccidian infection resistance in greenfinches.

Differential exposure or sensitivity to stressors can have substantial effects on the variation in immune responsiveness of animals. However, the questions about the causes and consequences of these processes have remained largely unclear, particularly as regards wild animals and their natural pathogens. Here we ask how a potential marker of stress responses, the feather corticosterone (CORT) content, reflects the resistance to an experimental infection with natural coccidian parasites in wild-caught captive greenfinches (Carduelis chloris). CORT content of tail feathers grown in captivity correlated positively with a behavioural measure of captivity-intolerance, i.e., the amount of damage accrued to tail feathers in captivity that results from flapping against cage bars. This finding is consistent with an idea that feather CORT reflects the amount of stress experienced during feather growth. Experimental infection with heterologous coccidian strains increased feather CORT levels. Birds with highest feather CORT levels appeared most resistant to new infection, assessed on the basis of parasite oocyst shedding at the peak phase of infection. Birds with highest feather CORT levels also cleared the infection faster than the birds with lower feather CORT levels. These findings provide the first evidence about positive covariation between feather CORT and resistance to a natural pathogen in a wild bird species. Assuming that feather CORT levels reflect circulating hormone titres, these findings suggest that parasite-mediated selection may contribute to maintenance of phenotypes with high corticosterone responsiveness to stress, despite potential negative behavioural consequences.

Differential susceptibility to the Withering Syndrome agent and renal coccidia in juvenile Haliotis rufescens, Haliotis discus hannai and the interspecific hybrid.

Withering Syndrome (WS) is a pathogenic chronic disease caused by the intracellular rickettsial-like bacterium "Candidatus Xenohaliotis californiensis" (WS-RLOs), which affects many abalone species. The renal coccidium (Margolisiella haliotis) has often been observed concurrent with WS infection. The red abalone Haliotis rufescens is a very susceptible species to WS and is also infected by the coccidium M. haliotis. In contrast, the Japanese abalone Haliotis discus hannai is not infected by these parasites. Interspecific hybridization is a method for improving important traits in animal husbandry. The objective of this study was to determine susceptibility to WS-RLO and M. haliotis infection in the hybrid generated from a cross between red and Japanese abalones. Juveniles from both species and the interspecific hybrid were challenged by exposure to effluent from red abalone adults infected with both parasites. The animals were analyzed by histology at 130days post-challenge. A 33% prevalence WS-RLOs was observed in the red abalone H. rufescens, whereas a 20% prevalence was observed in the hybrid. Infections were graded on a scale of 0-3. Of these red abalones infected, 53% presented grade 1 infection intensity, 10% had grade 2 infections, and 50% had grade 3 infections. However, the hybrids only presented intensities at the extremes of the scale; of those infected 33% showed grade 1 infections and 66% had grade 3 infections. The coccidium prevalence was 7% in red abalone individuals and 13% in the hybrid abalone. In contrast, the Japanese abalone did not present infections with either parasite. As with the prevalence, the infection intensities for the coccidium were higher in the hybrid abalone; of those infected 25% had grade 2 infections, and 75% had grade 3 infections, but the red abalone presented only grade 2 infection intensities. Therefore, the hybrid did not inherited non-susceptibility or resistance characteristics of the parental H. discus hannai and possessed biological conditions that could foster development of both parasites. Development of a culture based on this hybrid abalone should consider its susceptibility to infection by coccidian, WS-RLOs and the potential for developing the WS disease.

Anurans as paratenic hosts in the transmission of Hepatozoon caimani to caimans Caiman yacare and Caiman latirostris.

Prevalence of Hepatozoon caimani has been reported in 76% of caimans Caiman yacare from the Pantanal region. Culex (Melanoconion) spp. mosquitoes were recently identified as natural vectors of this parasite. However, culicids are not typically eaten by crocodilians, suggesting that the main transmission route is through ingestion of insectivorous vertebrates, such as anurans. The susceptibility of wild frogs Leptodactylus chaquensis, Leptodactylus podicipinus and Scinax nasicus to infection by H. caimani was verified. Wild-caught anurans were force fed with sporulated oocysts from laboratory-bred Culex (Melanoconion) mosquitoes. Frogs were killed 30 days postinfection, and their internal organs were fed to caimans C. yacare and Caiman latirostris. Cystozoites were identified in fresh liver impression smears of L. chaquensis. C. yacare fed on anuran organ presented gametocytes in peripheral blood circulation between 74 and 80 days postinoculation (dpi). Gametocytes were also verified in C. latirostris fed on the internal organs of L. podicipinus and S. nasicus between 60-70 and 69-75 dpi, respectively. Since frogs used in experiment are sympatric with C. yacare and C. latirostris and may occur in the diet of these caimans, the results suggest these amphibians are paratenic hosts in the natural transmission cycle of H. caimani in Pantanal.

Occurrence of anti-Neospora caninum antibodiesin dogs in rural areas in Minas Gerais, Brazil / Ocorrência de anticorpos anti-Neospora caninum em cães de áreas rurais em Minas Gerais, Brasil

The aim of this study was to determine the frequency of anti-Neospora caninum antibodies and risk factors associated with seropositivity in 240 dogs from rural areas of the Lavras, Belo Horizonte and Nanuque regions, state of Minas Gerais, Brazil. The indirect fluorescence antibody test (IFAT) with a cutoff of 50 was used to assess the frequency of seropositive dogs. The risk factor analysis was performed using the Chi-square test (χ2) and multiple logistic regression. The frequency of seropositivity for N. caninum was 15% of the dogs (36/240). Presence of dogs without defined breed (p = 0.018; OR = 5.9) and presence of cattle on the farm (p = 0.053, OR = 4.3) were associated with N. caninum seropositivity. Dogs in the Nanuque region had higher seropositivity for N. caninum (29.9%) than did those in the Lavras (6.2%) and Belo Horizonte (2.2%) regions (p < 0.05). The presence of seropositive dogs in rural areas of Minas Gerais demonstrates the potential risk of horizontal transmission of N. caninum to cattle, especially from dogs without defined breed, which were four times more likely to be seropositive than purebred dogs were.

O objetivo deste estudo foi determinar a frequência de anticorpos anti-Neospora caninum e fatores de risco associados à soropositividade, em 240 cães de áreas rurais, nas regiões de Lavras, Belo Horizonte e Nanuque, Minas Gerais, Brasil. Foi utilizada a reação de imunofluorescência indireta (RIFI), com um ponto de corte igual a 50, para avaliar a frequência de cães soropositivos. A análise dos fatores de risco foi realizada pelo teste de Qui-quadrado (χ2) e regressão logística múltipla. A frequência de cães soropositivos para N. caninum foi de 15% (36/240). A presença de cães sem raça definida (SRD) (p = 0,018; OR = 5,9) e bovinos na propriedade (p = 0,053; OR = 4,3) foi associada à soropositividade pelo N. caninum. A frequência de cães soropositivos foi mais elevada na região de Nanuque (29,9%), quando comparados aos das regiões de Lavras (6,2%) e Belo Horizonte (2,2%) (p < 0,05). A presença de cães soropositivos, em áreas rurais de Minas Gerais, demonstra o risco potencial da transmissão horizontal de N. caninum para os bovinos, especialmente os cães SRD, que apresentaram quatro vezes mais a chance de serem soropositivos em relação aos cães com raça definida.

Genetic diversity of Amoebophryidae (Syndiniales) during Alexandrium catenella/tamarense (Dinophyceae) blooms in the Thau lagoon (Mediterranean Sea, France).

During toxic spring and fall blooms produced by the dinoflagellate Alexandrium in the Thau lagoon (Mediterranean Sea), we monitored the presence of Amoebophryidae (Syndiniales), a group of parasites virulent toward a wide range of dinoflagellate hosts. A PCR-biased approach unveiled the presence of at least 10 different parasitic groups during Alexandrium proliferation. However, fluorescent in situ hybridization failed to reveal parasitic infection inside Alexandrium cells in field populations. In contrast, several co-occurring, less abundant thecate dinoflagellate species were infected by Amoebophryidae, showing up to 10% of infected cells. We concluded that Alexandrium populations were not infected by these local parasites, at least during our survey. In order to check this resistance capacity on a more global scale, we cross-infected several Alexandrium strains isolated from the Thau lagoon with one strain of the parasite Amoebophrya sp. originating from Salt Pond, MA, USA. All of these hosts were strongly infected by the North American parasite, leading to the conclusion that blooming Alexandrium in the Thau lagoon were not particularly resistant to this kind of parasite. These results provide additional evidence that dinoflagellates may become invasive when they successfully escaped their natural enemies in time and/or space (the "enemy release" hypothesis).

Evolution of clinical, haematological and biochemical findings in young dogs naturally infected by vector-borne pathogens.

Longitudinal studies evaluating the evolution of clinical, haematological, biochemical findings in young dogs exposed for the first time to multiple vector-borne pathogens have not been reported. With the objective of assessing the evolution of clinical, haematological and biochemical findings, these parameters were serially monitored in naturally infected dogs throughout a 1-year follow-up period. Young dogs, infected by vector-borne pathogens based on cytology or polymerase chain reaction, were examined clinically and blood samples were obtained at seven different follow-up time points. Dogs were randomized to group A (17 dogs treated with a spot-on formulation of imidacloprid 10% and permethrin 50%) or to group B (17 dogs untreated). In addition, 10 4-month-old beagles were enrolled in each group and used as sentinel dogs. At baseline, Anaplasma platys was the most frequently detected pathogen, followed by Babesia vogeli, Bartonella spp., Ehrlichia canis and Hepatozoon canis. Co-infections with A. platys and B. vogeli, followed by E. canis and B. vogeli, A. platys and H. canis and A. platys and Bartonella spp. were also diagnosed. In dogs from group B, abnormal clinical signs were recorded at different time points throughout the study. No abnormal clinical signs were recorded in group A dogs. Thrombocytopenia was the most frequent haematological alteration recorded in A. platys-infected dogs, B. vogeli-infected dogs and in dogs co-infected with A. platys and B. vogeli or A. platys and Bartonella spp. Lymphocytosis was frequently detected among dogs infected with B. vogeli or co-infected with A. platys and B. vogeli. Beagles were often infected with a single pathogen rather than with multiple canine vector-borne pathogens. There was a significant association (p<0.01) between tick infestation and A. platys or B. vogeli, as single infections, and A. platys and B. vogeli or A. platys and Bartonella spp. co-infections. This study emphasizes the clinical difficulties associated with assigning a specific clinical sign or haematological abnormality to a particular canine vector-borne disease.

Carotenoid-based bill colour is an integrative signal of multiple parasite infection in blackbird.

In the study of parasite-mediated sexual selection, there has been controversial evidence for the prediction that brighter males should have fewer parasites. Most of these studies have focused on one parasite species. Our aim was to investigate the expression of carotenoid-based coloured signals in relation to patterns of multiple parasite infections, to determine whether colour reflects parasite load of all parasite species, or whether different relationships might be found when looking at each parasite species independently. We investigated the relationship between bill colour, body mass and plasma carotenoids and parasite load (feather chewing lice, blood parasite Plasmodium sp., intestinal parasites cestodes and coccidia) in the blackbird (Turdus merula). Bill colour on its own appeared to be a poor predictor of parasite load when investigating its relationships with individual parasite species. Variation in parasite intensities at the community level was summarised using principal component analysis to derive synthetic indexes of relative parasite species abundance and absolute parasite load. The relative abundance of parasite species was strongly related to bill colour, plasma carotenoid levels and body mass: birds with relatively more cestodes and chewing lice and relatively less Plasmodium and coccidia had a more colourful bill, circulated more carotenoids and were heavier. These results suggest that bill colour more accurately reflects the relative intensities of parasite infection, rather than one-by-one relationships with parasites or absolute parasite burden. Investigating patterns of multiple parasite infection would thus improve our understanding of the information conveyed by coloured signals on parasite load.

Carotenoids modulate the effect of coccidian infection on the condition and immune response in moulting house sparrows.

In the present study, we experimentally manipulated coccidian parasitism and dietary carotenoid availability in a fully factorial experiment in male house sparrows (Passer domesticus Linnaeus), and tested whether carotenoid supplementation reduces the cost of parasitism in terms of condition, moult and immune responses. We found that coccidians have a significant but transient negative effect on body mass, which can be reduced if birds have access to carotenoid supplementation in their diet. Experimental manipulation had no significant effect on the moulting parameters of the birds measured following coccidian infestation and during the whole moulting period. Carotenoid supplementation increased the plasma carotenoid concentration in both infested and medicated birds treated with a coccidiostatic drug; however, after two months exposure to parasites, plasma carotenoid concentration increased only in the carotenoid-supplemented and medicated group whereas no difference was observed between the carotenoid-supplemented and infested and non-supplemented groups. On the contrary, coccidian infestation was not affected by carotenoid supplementation. Experimental infestation decreased the antibody response to sheep red blood cells (SRBCs), although no significant effect was observed in the capacity of the birds to respond to a mitogenic challenge with phytohemagglutinin. Within the experimentally infested groups birds with carotenoid-supplemented food tended to have an increased anti-SRBC humoral immune response. The positive correlation between coccidian infestation and the strength of the humoral immune response against SRBCs in the non-supplemented and infested groups indicates that this part of the immune system plays an important role in defence against these parasites.

[Dynamics of endoparasite infections in rabbits at different rearing regimes]. / Dynamika zarazenia królików endopasozytami w róznych warunkach chowu.

This study was intended to evaluate the occurrence and seasonality of infection of coccidian and helminth parasites, in three rabbit warrens differently managed. Mothers stayed with their offspring on deep litter (farm A, 90 dams), in boxes cleaned weekly (farm B, 30 dams) or on slatted floor (farm C, 10 females), whereas all the young after weaning (1 to 5 months of age) were kept in cages with slatted floor. Animals were fed a complete balanced pelleted feed (warrens A and B) or traditional forage (herd C). Antiparasitic treatment involved coccidiostatic drugs. Robenidine (alternately with Lerbec in farm A) was added to food in the first two farms, whilst Sulfatyf mixed with water was given once after weaning in farm C. A total of 203 individual faecal samples from females of breeding stock, and 133 pooled samples from young animals, were collected on an annual cycle during 2007-2008 (February-January), and analyzed according to a modified concentration McMaster method. Coccidians were identified based on sporulated oocysts. A number of coccidian species (Eimeria perforans, E. media, E. magna, E. irresidua, E. exiqua, E. coecicola, and E. piriformis) were observed in all farms. The most pathogenic species--E. intestinalis was found both in farm A and B, whereas E. flavescens and E. stiedae--only in the former. The level of infection was high, especially in young rabbits, with the prevalence of 94.9 to 100% and mean intensity from 11,161 to 28,871 oocysts per 1 g of faeces (OPG) in a particular warren. The highest intensity of infection was observed in May, when the mean output increased to 29,454, 56,952, and 23,815 OPG in warrens A, B, and C, respectively. A nematode, Passalurus ambiguus, was detected in all searched farms, with the prevalence from 14.1% to 27.5%, depending on a farm. The species was more often seen in the first part of year. The other helminths (Trichostrongylus retortaeformis, Graphidium strigosum, and Trichuris leporis) were found only in rabbits of warren C. In this warren, the forage of farm origin was suggested to be prepared in a proper way in order to protect it from nematode transmission. The presence of coccidia and their specific composition has been continuously monitored in all farms, to estimate the efficiency of prophylactic measures undertaken.