Urbanization correlates with the prevalence and richness of blood parasites in Eurasian Blackbirds (Turdus merula)

Urbanization is increasing worldwide, producing severe environmental impacts. Biodiversity is affected by the expansion of cities, with many species being unable to cope with the different human-induced stressors present in these landscapes. However, this knowledge is mainly based on research from taxa such as plants or vertebrates, while other organisms like protozoa have been less studied in this context. The impact of urbanization on the transmission of vector-borne pathogens in wildlife is still unclear despite its relevance for animal and human health. Here, we investigated whether cities are associated with changes in the prevalence and richness of lineages of three vector-borne protozoans (Plasmodium, Haemoproteus and Leucocytozoon) in Eurasian blackbirds (Turdus merula) from multiple urban and forest areas in Europe. Our results show important species-specific differences between these two habitat types. We found a significant lower prevalence of Leucocytozoon in urban birds compared to forest birds, but no differences for Plasmodium and Haemoproteus. Furthermore, the richness of parasite lineages in European cities was higher for Plasmodium but lower for Leucocytozoon than in forests. We also found one Plasmodium lineage exclusively from cities while another of Leucocytozoon was only found in forests suggesting a certain level of habitat specialization for these protozoan vectors. Overall, our findings show that cities provide contrasting opportunities for the transmission of different vector-borne pathogens and generate new scenarios for the interactions between hosts, vectors and parasites.

Higher body condition with infection by Haemoproteus parasites in Bananaquits (Coereba flaveola)

Parasite transmission is a heterogenous process in host-parasite interactions. This heterogeneity is particularly apparent in vector-borne parasite transmission where the vector adds an additional level of complexity. Haemosporidian parasites, a widespread protist, cause a malaria-like disease in birds globally, but we still have much to learn about the consequences of infection to hosts' health. In the Caribbean, where malarial parasites are endemic, studying host-parasites interactions may give us important insights about energetic trade-offs involved in malarial parasites infections in birds. In this study, we tested the consequences of Haemoproteus infection on the Bananaquit, a resident species of Puerto Rico. We also tested for potential sources of individual heterogeneity in the consequences of infection such as host age and sex. To quantify the consequences of infection to hosts' health we compared three complementary body condition indices between infected and uninfected individuals. Our results showed that Bananaquits infected by Haemoproteus had higher body condition than uninfected individuals. This result was consistent among the three body condition indices. Still, we found no clear evidence that this effect was mediated by host age or sex. We discuss a set of non-mutually exclusive hypotheses that may explain this pattern including metabolic syndrome, immunological responses leading to host tolerance or resistance to infection, and potential changes in consumption rates. Overall, our results suggest that other mechanisms, may drive the consequences of avian malarial infection.

Energy input, habitat heterogeneity and host specificity drive avian haemosporidian diversity at continental scales

The correct identification of variables affecting parasite diversity and assemblage composition at different spatial scales is crucial for understanding how pathogen distribution responds to anthropogenic disturbance and climate change. Here, we used a database of avian haemosporidian parasites to test how the taxonomic and phylogenetic diversity and phylogenetic structure of the genera Plasmodium, Haemoproteus and Leucocytozoon from three zoogeographic regions are related to surrogate variables of Earth's energy input, habitat heterogeneity (climatic diversity, landscape heterogeneity, host richness and human disturbance) and ecological interactions (resource use), which was measured by a novel assemblage-level metric related to parasite niche overlap (degree of generalism). We found that different components of energy input explained variation in richness for each genus. We found that human disturbance influences the phylogenetic structure of Haemoproteus while the degree of generalism explained richness and phylogenetic structure of Plasmodium and Leucocytozoon genera. Furthermore, landscape attributes related to human disturbance (human footprint) can filter Haemoproteus assemblages by their phylogenetic relatedness. Finally, assembly processes related to resource use within parasite assemblages modify species richness and phylogenetic structure of Plasmodium and Leucocytozoon assemblages. Overall, our study highlighted the genus-specific patterns with the different components of Earth's energy budget, human disturbances and degree of generalism.

The association between haemosporidian infection and non-breeding moult location in great reed warblers revisited by combining feather stable isotope profiles and geolocator data

Stable isotope analysis provides valuable insights into the ecology of long-distance migratory birds during periods spent away from a specific study site. In a previous study, Swedish great reed warblers (Acrocephalus arundinaceus) infected with haemosporidian parasites differed in feather isotope ratios compared to non-infected birds, suggesting that infected and non-infected birds spent the non-breeding season in different locations or habitats. Here, we use a novel dataset comprising geolocator data, isotopes, and haemosporidian infection status of 92 individuals from four Eurasian populations to investigate whether parasite transmission varies with geography or habitats. We found that the probability of harbouring Plasmodium and Leucocytozoon parasites was higher in birds moulting in the eastern region of the non-breeding grounds. However, no geographic pattern occurred for Haemoproteus infections or overall infection status. In contrast to the previous study, we did not find any relationship between feather isotope ratios and overall haemosporidian infection for the entire current dataset. Plasmodium-infected birds had lower feather δ15N values indicating that they occupied more mesic habitats. Leucocytozoon-infected birds had higher feather δ34S values suggesting more coastal sites or wetlands with anoxic sulphate reduction. As the composition and prevalence of haemosporidian parasites differed between the old and the current dataset, we suggest that the differences might be a consequence of temporal dynamics of haemosporidian parasites. Our results emphasize the importance of replicating studies conducted on a single population over a restricted time period, as the patterns can become more complex for data from wider geographical areas and different time periods.

Co-infecting Haemoproteus species (Haemosporida, Apicomplexa) show different host tissue tropism during exo-erythrocytic development in Fringilla coelebs (Fringillidae)

Avian haemosporidians of the genera Plasmodium, Haemoproteus, and Leucocytozoon are common blood parasites in wild birds all over the world. Despite their importance as pathogens potentially compromising host fitness and health, little is known about the exo-erythrocytic development of these parasites, particularly during co-infections which predominate in wildlife. This study aimed to address this issue using Haemoproteus parasites of Fringilla coelebs, a common bird species of the Western Palearctic and host to a variety of haemosporidian parasite lineages. Blood and tissue samples of 20 F. coelebs, positive for haemosporidians by blood film microscopy, were analysed by PCR and sequencing to determine cytochrome b lineages of the parasites. Tissue sections were examined for exo-erythrocytic stages by histology and in situ hybridization applying genus-, species-, and lineage-specific probes which target the 18S rRNA of the parasites. In addition, laser microdissection of tissue stages was performed to identify parasite lineages. Combined molecular results of PCR, laser microdissection, and in situ hybridization showed a high rate of co-infections, with Haemoproteus lineages dominating. Exo-erythrocytic meronts of five Haemoproteus spp. were described for the first known time, including Haemoproteus magnus hCCF6, Haemoproteus fringillae hCCF3, Haemoproteus majoris hCCF5, Haemoproteus sp. hROFI1, and Haemoproteus sp. hCCF2. Merogonic stages were observed in the vascular system, presenting a formerly unknown mode of exo-erythrocytic development in Haemoproteus parasites. Meronts and megalomeronts of these species were distinct regarding their morphology and organ distribution, indicating species-specific patterns of merogony and different host tissue tropism. New pathological aspects of haemoproteosis were reported. Furthermore, phylogenetic analysis of Haemoproteus spp. with regard to their exo-erythrocytic stages points towards separation of non-megalomeront-forming species from megalomeront-forming species, calling for further studies on exo-erythrocytic development of haemosporidian parasites to explore the phylogenetic character of this trait.

Contribution to ecological environmental factors and the occurrence of haemosporidians in birds in Zhongar Alatau National Park, Kazakhstan

In addition to the presence of a suitable host and vector, the prevalence of haemosporidians is influenced by several important factors, including the environmental conditions of the habitat, which depend on broader geographic characteristics. The aim of this study is to perform a preliminarily assessment of the distribution of blood parasites in birds from the mountainous area of Zhongar Alatau NP and to find potential new sites for research on their ecology in Kazakhstan. The results of this research constitute the first report on the occurrence of blood parasites from this area. A total of 58 birds, from the order Passeriformes and one individual from the order Caprimulgiformes, were examined during the study. The overall prevalence of infections caused by haemosporidian parasites (Haemoproteus, Leucocytozoon) was 18.6%. Neither the genus Plasmodium nor the presence of trypanosomes and microfilariae was detected in the birds examined. Three birds (5.1% prevalence) were infected with parasites of the genus Haemoproteus, in all eleven positive birds the analyses showed the presence of parasites of the genus Leucocytozoon (18.6% prevalence). The presence of parasites genus Haemoproteus was detected only in birds that were also infected with Leucocytozoon parasites. More infections with parasites of the genus Leucocytozoon are predicted due to the higher altitude and ecological factors at the capture sites, which are more favourable for the development of vectors of this genus. The species Haemoproteus majoris was detected in the host Emberiza cioides and species Haemoproteus minutus in host Turdus merula. Other species of this genus in the hosts Cyanistes cyanus and Turdus atrogularis were not determined. The species Leucocytozoon fringilinarum was detected in the hosts Cyanistes cyanus and Parus major, Leucocytozoon dubreuili was detected in Turdus atrogularis and Turdus merula. In the other host species Aegithalos caudatus, Emberiza cioides and Periparus aterus, it was not possible to dermine the species of the genus Leucocytozoon.

First detection of herpesvirus and hemosporidians in the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus)

Pathogens affect wild bird populations worldwide, contributing to their decline. Considering the scarce health data regarding the endangered Pyrenean Capercaillie (Tetrao urogallus aquitanicus), we molecularly surveyed selected pathogens (Newcastle disease virus, Avian influenza virus, Chlamydia psittaci, avian pathogenic Escherichia coli, Campylobacter jejuni, and Salmonella spp.) in 30 Pyrenean Capercaillie feces collected in the field (Catalonia, northeastern Spain). Additionally, swab and tissue samples from eight wild Pyrenean Capercaillies of Catalonia and Andorra were molecularly tested for herpesvirus and hemosporidians (Plasmodium spp., Haemoproteus spp., and Leucocytozoon spp.). All fecal samples were negative for the pathogens tested. Nevertheless, we detected a novel herpesvirus in 50% (4/8) of the Pyrenean Capercaillies, and hemosporidian DNA in 62.5% (5/8) of the tissue samples (i.e., Haemoproteus sp. [4 of 8] and/or Leucocytozoon sp. [3 of 8]). To our knowledge, this is the first detection of herpesvirus and hemosporidians infections in Pyrenean Capercaillies. The putative novel herpesvirus belongs to the genus Iltovirus. The presence of hemosporidian parasites in this mountain bird species is of concern, and could be related to the marked increase in the average temperature in the Pyrenees as a consequence of climate change. Our findings are fundamental to improve the conservation plans for the endangered Pyrenean Capercaillie population.

First report of Culicoides caucoliberensis in Spain: Exploring molecular phylogeny, host-feeding behaviour and avian haemosporidian parasites

Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of pathogens that affect wildlife and livestock. Understanding the composition and distribution of vector species is crucial for implementing control strategies and preventing the spread of infectious diseases. This study provides a morphological and molecular characterisation of Culicoides caucoliberensis, which represents the first record for Spain, increasing the number of Culicoides species in the country to 85. A total of 213 specimens were collected using Onderstepoort-ultraviolet down-draught light traps on a rocky coastline in the Balearic Islands during two sampling periods in 2022. Phylogenetic analysis showed that C. caucoliberensis forms a monophyletic cluster within the Maritimus group. Host preferences were determined for the first time and showed propensity to feed on the European shag (Phalacrocorax aristotelis). The vector role of C. caucoliberensis for haemosporidian transmission remains unclear since molecular detection of Haemosporidians (Haemoproteus and Plasmodium) was negative for all the pools of parous and engorged females analysed. This study emphasises the importance of conducting entomofauna studies in lesser-known Mediterranean islet landscapes and highlights the need for research on vectors within the One Health framework.

Haemosporidian parasite infections of Malagasy Philepittidae and Nectariniidae are driven by phylogeny rather than ecology

The nectarivorous common sunbird asity (Neodrepanis coruscans) is phylogenetically closely related to the frugivorous velvet asity (Philepitta castanea), yet it shares similar habitat and foraging behaviour as the Malagasy sunbirds (Cinnyris spp.). As ecological factors have been shown to influence blood parasite prevalence, it should be tested whether parasite abundance, prevalence and diversity of N. coruscans are more similar to the sunbirds than to its relative. Therefore, blood samples (n = 156) and smears (n = 60) were tested for different blood parasites (Haemosporida, trypanosomes, filarioid nematodes) using molecular and microscopic methods. High prevalence of haemosporidian parasites was observed in all bird taxa, with rates ranging from 23% in N. coruscans to 84.6% in C. notatus. The Malagasy Cinnyris spp. exhibited a high occurrence of mixed haemosporidian infections (>76%) with various specialized lineages. Within the Philepittidae family, no Haemoproteus infection was detected and just a few cases of mixed infections. Nectariniidae species predominantly had specialized haemosporidian lineages, while Philepittidae had infections mainly caused by generalist lineages. These findings emphasize the diverse range of blood parasites in Nectariniidae, while additionally highlighting the high diversity of trypanosomes and filarioid nematodes in Philepittidae. Additionally, several newly discovered haemosporidian lineages, Trypanosoma isolates and filarioid nematode isolates were identified. Notably, Philepittidae exhibited a lower prevalence of avian haemosporidian parasites compared to Nectariniidae, possibly due to potential resistance mechanisms. Despite N. coruscans sharing similar habitat and behavioural ecology with both Cinnyris spp., it closely resembles its relative, P. castanea, in all aspects of haemosporidian parasitism.

First investigation of blood parasites of bats in Burkina Faso detects Hepatocystis parasites and infections with diverse Trypanosoma spp

Bats are hosts to a large diversity of eukaryotic protozoan blood parasites that comprise species of Trypanosoma and different haemosporidian parasite taxa and bats have played an important role in the evolutionary history of both parasite groups. However, bats in several geographical areas have not been investigated, including in Burkina Faso, where no information about malaria parasites and trypanosomes of bats exists to date.In this study, we collected data on the prevalence and the phylogenetic relationships of protozoan blood parasites in nine different bat species in Burkina Faso. Hepatocystis parasites were detected in two species of epauletted fruit bats, and a relatively high diversity of trypanosome parasites was identified in five bat species. The phylogenetic analyses recovered the trypanosome parasites of the bat species Rhinolophus alcyone and Nycteris hispida as close relatives of T. livingstonei, the trypanosome infections in Scotophilus leucogaster as closely related to the species T. vespertilionis and the trypanosomes from Pipistrellus nanulus and Epomophorus gambianus might present the species T. dionisii. These findings of the first investigation in Burkina Faso present a first snapshot of the diversity of protozoan blood parasites in bats in this country.

Unravelling the mosquito-haemosporidian parasite-bird host network in the southwestern Iberian Peninsula: insights into malaria infections, mosquito community and feeding preferences

BAKGROUND

Vector-borne diseases affecting humans, wildlife and livestock have significantly increased their incidence and distribution in the last decades. Because the interaction among vectors-parasite-vertebrate hosts plays a key role driving vector-borne disease transmission, the analyses of the diversity and structure of vector-parasite networks and host-feeding preference may help to assess disease risk. Also, the study of seasonal variations in the structure and composition of vector and parasite communities may elucidate the current patterns of parasite persistence and spread as well as facilitate prediction of how climate variations may impact vector-borne disease transmission. Avian malaria and related haemosporidian parasites constitute an exceptional model to understand the ecology and evolution of vector-borne diseases. However, the characterization of vector-haemosporidian parasite-bird host assemblages is largely unknown in many regions.

METHODS

Here, we analyzed 5859 female mosquitoes captured from May to November in five localities from southwestern Spain to explore the composition and seasonal variation of the vector-parasite-vertebrate host network.

RESULTS

We showed a gradual increase in mosquito abundance, peaking in July. A total of 16 different haemosporidian lineages were found infecting 13 mosquito species. Of these assemblages, more than 70% of these vector-parasite associations have not been described in previous studies. Moreover, three Haemoproteus lineages were reported for the first time in this study. The prevalence of avian malaria infections in mosquitoes varied significantly across the months, reaching a maximum in November. Mosquito blood-feeding preference was higher for mammals (62.5%), whereas 37.5% of vectors fed on birds, suggesting opportunistic feeding behavior.

CONCLUSION

These outcomes improve our understanding of disease transmission risk and help tovector control strategies.

Co-infection with Leucocytozoon and Other Haemosporidian Parasites Increases with Latitude and Altitude in New World Bird Communities

Establishing how environmental gradients and host ecology drive spatial variation in infection rates and diversity of pathogenic organisms is one of the central goals in disease ecology. Here, we identified the predictors of concomitant infection and lineage richness of blood parasites in New Word bird communities. Our multi-level Bayesian models revealed that higher latitudes and elevations played a determinant role in increasing the probability of a bird being co-infected with Leucocytozoon and other haemosporidian parasites. The heterogeneity in both single and co-infection rates was similarly driven by host attributes and temperature, with higher probabilities of infection in heavier migratory host species and at cooler localities. Latitude, elevation, host body mass, migratory behavior, and climate were also predictors of Leucocytozoon lineage richness across the New World avian communities, with decreasing parasite richness at higher elevations, rainy and warmer localities, and in heavier and resident host species. Increased parasite richness was found farther from the equator, confirming a reverse Latitudinal Diversity Gradient pattern for this parasite group. The increased rates of Leucocytozoon co-infection and lineage richness with increased latitude are in opposition with the pervasive assumption that pathogen infection rates and diversity are higher in tropical host communities.

Hemoparasite occurrence and hematological/serum chemistry variations in Podocnemis vogli turtles: A comparative analysis between wild-residing infected specimens and captive non-infected counterparts

Reptiles show a high occurrence of hemoparasites in the wild; however, little is known about the impact of such infections on their hosts' physiology and health status. Podocnemis vogli is an ancient turtle distributed in South America, frequently infected by blood parasites. Specifically, we analyzed the hematological and serum chemistry parameters of 78 wild turtles. We compared these values with those obtained from non-infected turtles of the same species in ex-situ conditions, considering factors such as sex and coinfections. Two orders of hemoparasites were detected under microscopic analyses: Adelorina, represented by Haemogregarina sp. (98.72 ± 0.28%), and Haemosporida, represented by Haemocystidium sp. (30.77 ± 1.16%), the latter genus being always in coinfection with Haemogregarina. Significant differences were observed in 20 parameters between infected (free living) and uninfected (living in captivity) turtles. The ALP, PCV, Hb, and MCV were significantly different by sex; albumin, cholesterol, creatinine, percentage of heterophils, lymphocytes, and basophils differed in coinfection. This is the first report of reference intervals of P. vogli in the wild and the first study comparing hematological and blood biochemistry values between hemoparasite-infected and uninfected P. vogli turtles. However, the limited knowledge of these parameters in wild reptiles and the wide range of interval values makes it difficult to determine any significant impact on turtle health. Nevertheless, this study highlights the need for more in-depth research to explore the potential effects of blood parasite infections on turtles, including immune response and coevolution studies.

CLINICAL AND SUBCLINICAL CYTAUXZOON FELIS INFECTIONS IN DOMESTIC CATS FROM A RECENTLY IDENTIFIED ENDEMIC REGION

Cytauxzoon felis is a tick-transmitted intraerythrocytic apicomplexan infecting felids in the southeastern and midwestern United States. Bobcats (Lynx rufus) are the natural wildlife reservoir of C. felis, where in enzootic areas prevalence can reach 100%. Domestic cats can be subclinically infected with C. felis or can develop cytauxzoonosis. Two studies have documented the presence of C. felis in domestic cats in Illinois; these studies have shown a limited number of cases submitted to specialty labs. During 2014-2018, we obtained blood samples collected by veterinary staff from 514 cats that were apparently healthy and 74 cats that were suspected of cytauxzoonosis. These samples were screened using a sensitive, nested PCR to detect the presence of C. felis DNA. We herein document frequent occurrences of cytauxzoonosis (8-15 cases/year from 4 veterinary clinics) and 12.5% prevalence of subclinical infections in southern Illinois, a locality showing a sharp increase in cases of cytauxzoonosis. Our results suggest a high risk of cytauxzoonosis in southern Illinois, despite only recently being recognized in the area. We found no specific risk factors for cytauxzoonosis or subclinical infections in this location. In addition, cases of cytauxzoonosis occur every month of the year (with the highest frequency in summer) and therefore tick prevention should be used in domestic cats in enzootic regions throughout the year.

Exo-erythrocytic development of two Haemoproteus species (Haemosporida, Haemoproteidae), with description of Haemoproteus dumbbellus, a new blood parasite of bunting birds (Emberizidae)

Avian haemosporidians are widespread parasites categorized into four families of the order Haemosporida (Apicomplexa). Species of the subgenus Parahaemoproteus (genus Haemoproteus) belong to the Haemoproteidae and are transmitted by Culicoides biting midges. Reports of death due to tissue damage during haemoproteosis in non-adapted birds have raised concerns about these pathogens, especially as their exo-erythrocytic development is known for only a few Haemoproteus spp. More research is needed to better understand the patterns of the parasites' development in tissues and their impact on avian hosts. Yellowhammers Emberiza citrinella (Emberizidae) and common house martins Delichon urbicum (Hirundinidae) were screened for Haemoproteus parasites by microscopic examination of blood films and PCR-based testing. Individuals with single infection were selected for histological investigations. H & E-stained sections were screened for detection and characterization of the exo-erythrocytic stages, while chromogenic in situ hybridization (CISH) and phylogenetic analysis were performed to confirm the Haemoproteus origin and their phylogenetic relationships. Haemoproteus dumbbellus n. sp. was discovered in Emberiza citrinella single-infected with the lineage hEMCIR01. Meronts of H. dumbbellus n. sp. developed in various organs of five of six tested individuals, a pattern which was reported in other Haemoproteus species clustering in the same clade, suggesting this could be a phylogenetic trait. By contrast, in Delichon urbicum infected with the Haemoproteus lineage hDELURB2, which was linked to the more distantly related parasite Haemoproteus hirundinis, only megalomeronts were found in the pectoral muscles of two of six infected individuals. All exo-erythrocytic stages were confirmed to be Haemoproteus parasites by CISH using a Haemoproteus genus-specific probe. While the development of meronts seems to be typical for species of the clade containing H. dumbbellus, further investigations and data from more species are needed to explore whether a phylogenetic pattern occurs in meront or megalomeront formation.

The 18S rRNA genes of Haemoproteus (Haemosporida, Apicomplexa) parasites from European songbirds with remarks on improved parasite diagnostics

BACKGROUND

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

METHODS

The almost complete 18S rRNA genes of 19 Haemoproteus lineages of the subgenus Parahaemoproteus, which are common in passeriform birds from the Palaearctic, were sequenced. The PCR products of 20 blood and tissue samples containing 19 parasite lineages were subjected to molecular cloning, and ten clones in mean were sequenced each. The sequence features were analysed and phylogenetic trees were calculated, including sequence data published previously from eight additional Parahaemoproteus lineages. The geographic and host distribution of all 27 lineages was visualised as CytB haplotype networks and pie charts. Based on the 18S sequence data, species-specific oligonucleotide probes were designed to target the parasites in host tissue by in situ hybridization assays.

RESULTS

Most Haemoproteus lineages had two or more variants of the 18S gene like many Plasmodium species, but the maximum distances between variants were generally lower. Moreover, unlike in most mammalian and avian Plasmodium species, the 18S sequences of all but one parasite lineage clustered into reciprocally monophyletic clades. Considerably distinct 18S clusters were only found in Haemoproteus tartakovskyi hSISKIN1 and Haemoproteus sp. hROFI1. The presence of chimeric 18S variants in some Haemoproteus lineages indicates that their ribosomal units rather evolve in a semi-concerted fashion than according to a strict model of birth-and-death evolution.

CONCLUSIONS

Parasites of the subgenus Parahaemoproteus contain distinct 18S variants, but the intraspecific variability is lower than in most mammalian and avian Plasmodium species. The new 18S data provides a basis for more thorough investigations on the development of Haemoproteus parasites in host tissue using in situ hybridization techniques targeting specific parasite lineages.

Avian Malaria in wild birds from a wildlife rehabilitation center in Central Portugal

Avian haemosporidian (Haemoproteus, Leucocytozoon, Plasmodium) are vector-transmitted protozoan parasites highly prevalent in various bird species. Still, their importance for bird health, species decline, or impact on rehabilitation success is underestimated. This study aimed to determine the occurrence and diversity of haemosporidian parasites after necropsies of seventy wild birds from thirty-four species of twelve taxonomic orders. Detection of avian haemosporidian DNA was evaluated using PCR amplification of the cytochrome b gene. 48.6% of all sampled birds were positive, with 24.3% positive for Plasmodium spp./Haemoproteus spp. and 44.3% for Leucocytozoon spp. Mixed infections corresponded to 20% of all tested birds. Sequencing of several selected samples revealed the infection of Plasmodium matutinum, Plasmodium relictum and different lineages of Leucocytozoon spp. This study provides a baseline description of haemosporidian infections in wild birds from a rehabilitation center in central Portugal. The results show the necessity to test and monitor possible infections that undermine recovery processes for different birds. Further research into the occurrence of these haemosporidian species in birds kept in conservation centers is needed to understand the impact on bird health.

HIGH PREVALENCE OF CYTAUXZOON FELIS IN BOBCATS (LYNX RUFUS) ACROSS OKLAHOMA AND OCCURRENCE IN WEST TEXAS, USA

Cytauxzoonosis is a fatal tick-borne disease in domestic cats caused by infection with the apicomplexan Cytauxzoon felis. Bobcats are the natural wild-vertebrate reservoirs for C. felis, and infections are typically subclinical and chronic in this species. The present study was done to determine the prevalence and geographic distribution of C. felis infection in wild bobcats from Oklahoma and the occurrence in northwestern Texas. Tongue samples from 360 bobcats were collected from 53 counties in Oklahoma and 13 samples from three counties in Texas. For DNA extracted from each tongue sample, a probe-based droplet digital PCR assay was performed targeting the C. felis mitochondrial gene cytochrome c oxidase subunit III (cox3). Prevalence of C. felis infection was calculated for each county sampled, and data from individual counties were combined according to geographic regions and compared using chi-square tests. Overall prevalence of C. felis in bobcats from Oklahoma was 80.0% (95% confidence interval [CI], 75.6-83.8). The prevalence of infection was >90% for bobcats from central, northeastern, south-central, and southeastern regions of Oklahoma, but <68% for bobcats from northwestern and southwestern regions. Bobcats from central counties in Oklahoma were 25.693 times more likely to be infected with C. felis compared to all other bobcats sampled from the state. Higher prevalence estimates of C. felis in bobcats appeared to be in counties where known tick vectors are most common. Occurrence of C. felis in bobcats from northwestern Texas was 30.8% (95% CI, 12.4%-58.0%) based on 13 samples. Results of this study support the utilization of bobcats as sentinel animals to identify geographic areas with risk of C. felis infection to domestic cats.

Haemosporidians from a Neglected Group of Terrestrial Wild Birds in the Peruvian Amazonia

Haemosporidians are a widespread group of blood parasites transmitted by vectors. Despite their relevance for bird conservation, few studies have been conducted in the Amazonia and even less in terrestrial wild birds. We analysed blood samples from 168 game birds, collected from 2008 to 2015 by subsistence hunters of an indigenous rural community in the Peruvian Amazonia. DNA was tested for Haemoproteus spp., Plasmodium spp. and Leucocytozoon spp. and positive amplicons were sequenced and curated for phylogenetic analysis. Haemosporidian prevalence was 72% overall, 66.7% for Haemoproteus spp. and 5.4% for Plasmodium spp. and respectively by bird species: Spix's Guan (Penelope jacquacu, n = 72) 87.5% and 0%, Razor-billed Curassow (Mitu tuberosum, n = 45) 77.8% and 6.7%, White-winged Trumpeter (Psophia leucoptera, n = 20) 6.3% and 12.5%, Blue-throated Piping-guan (Pipile cumanensis, n = 16) 73.3% and 6.7%, and Great Tinamou (Tinamus major, n = 15) 10% and 15%. Leucocytozoon spp. was not found. P. leucoptera and T. major were less likely to be infected with Haemoproteus spp. Fruit abundance had a negative association with Haemoproteus spp. prevalence and precipitation was negatively associated with Plasmodium spp. prevalence. The 106 sequences examined represented 29 lineages, 82.8% of them were new lineages (Plasmodium n = 3, Haemoproteus n = 21). Novel host-parasite associations and lineages were unveiled, including probably new species of Plasmodium spp. Our results highlight the scientific value of alternative sampling methods and the collaboration with local communities.

Climate predictors and climate change projections for avian haemosporidian prevalence in Mexico

Long-term, inter-annual and seasonal variation in temperature and precipitation influence the distribution and prevalence of intraerythrocytic haemosporidian parasites. We characterized the climatic niche behind the prevalence of the three main haemosporidian genera (Haemoproteus, Plasmodium and Leucocytozoon) in central-eastern Mexico, to understand their main climate drivers. Then, we projected the influence of climate change over prevalence distribution in the region. Using the MaxEnt modelling algorithm, we assessed the relative contribution of bioclimatic predictor variables to identify those most influential to haemosporidian prevalence in different avian communities within the region. Two contrasting climate change scenarios for 2070 were used to create distribution models to explain spatial turnover in prevalence caused by climate change. We assigned our study sites into polygonal operational climatic units (OCUs) and used the general haemosporidian prevalence for each OCU to indirectly measure environmental suitability for these parasites. A high statistical association between global prevalence and the bioclimatic variables ‘mean diurnal temperature range’ and ‘annual temperature range’ was found. Climate change projections for 2070 showed a significant modification of the current distribution of suitable climate areas for haemosporidians in the study region.

Molecular detection of Leucocytozoon in red-legged seriemas (Cariama cristata), a non-migratory bird species in the Brazilian Cerrado

Avian Haemosporidian parasites - Plasmodium, Haemoproteus, Leucocytozoon and Fallisia - have a wide distribution except for Antarctica. Leucocytozoon sp. has been poorly described in Brazil, and few studies have indicated infections in birds from the Atlantic Forest, Pantanal, Pampa and Amazon biomes. This study describes, for the first time, the occurrence of Leucocytozoon infection in red-legged seriemas (Cariama cristata) in the Brazilian savanna (Cerrado biome) using molecular diagnosis. Leucocytozoon spp. lineage CARCRI01 was detected in three C. cristata, a non-migratory bird, confirming transmission in mid-elevation areas in central Brazil. Further studies are needed to certify whether infections in red-legged seriemas were not abortive and to elucidate Leucocytozoon infection at low altitudes in the Brazilian lands.

Urbanization effects on temporal variations of avian haemosporidian infections

Urbanization is an important human-driven process that leads to biodiversity loss and alters the interactions between organisms, including disease transmission. Although urbanization affects both host and vector communities, the effects on vector-borne pathogens are still poorly understood. Here, we monitored variation in prevalence and richness of three common blood parasites in birds (Plasmodium, Haemoproteus and Leucocytozoon) from localities with different land uses (urban, rural and natural) during two consecutive years (2013 and 2014). Overall, 1400 juvenile house sparrows (Passer domesticus) from 15 localities in southern Spain were included in this study. Haemoproteus and Leucocytozoon prevalence was higher in 2013 than in 2014, particularly in urban and natural habitats for the case of Leucocytozoon. Prevalence was correlated between years for Haemoproteus and Leucocytozoon, independently of the habitat. Additionally, rural habitats harboured significantly higher Haemoproteus lineage richness compared to urban and natural habitats during 2014. Leucocytozoon lineage richness was negatively correlated between years in rural habitats but positively correlated in urban and natural habitats in comparison. Parasite lineages found in birds were homogeneously distributed along habitats and years and the common lineages prevalence were not influenced by them. Our results highlight different patterns of infection depending on the parasite genera probably related to the composition and density of vector communities. The specific reproductive environmental requirements of the different groups of vectors involved in the transmission may be affected by climatic conditions and landscape features.

A field test of the dilution effect hypothesis in four avian multi-host pathogens

The Dilution Effect Hypothesis (DEH) argues that greater biodiversity lowers the risk of disease and reduces the rates of pathogen transmission since more diverse communities harbour fewer competent hosts for any given pathogen, thereby reducing host exposure to the pathogen. DEH is expected to operate most intensely in vector-borne pathogens and when species-rich communities are not associated with increased host density. Overall, dilution will occur if greater species diversity leads to a lower contact rate between infected vectors and susceptible hosts, and between infected hosts and susceptible vectors. Field-based tests simultaneously analysing the prevalence of several multi-host pathogens in relation to host and vector diversity are required to validate DEH. We tested the relationship between the prevalence in house sparrows (Passer domesticus) of four vector-borne pathogens-three avian haemosporidians (including the avian malaria parasite Plasmodium and the malaria-like parasites Haemoproteus and Leucocytozoon) and West Nile virus (WNV)-and vertebrate diversity. Birds were sampled at 45 localities in SW Spain for which extensive data on vector (mosquitoes) and vertebrate communities exist. Vertebrate censuses were conducted to quantify avian and mammal density, species richness and evenness. Contrary to the predictions of DEH, WNV seroprevalence and haemosporidian prevalence were not negatively associated with either vertebrate species richness or evenness. Indeed, the opposite pattern was found, with positive relationships between avian species richness and WNV seroprevalence, and Leucocytozoon prevalence being detected. When vector (mosquito) richness and evenness were incorporated into the models, all the previous associations between WNV prevalence and the vertebrate community variables remained unchanged. No significant association was found for Plasmodium prevalence and vertebrate community variables in any of the models tested. Despite the studied system having several characteristics that should favour the dilution effect (i.e., vector-borne pathogens, an area where vector and host densities are unrelated, and where host richness is not associated with an increase in host density), none of the relationships between host species diversity and species richness, and pathogen prevalence supported DEH and, in fact, amplification was found for three of the four pathogens tested. Consequently, the range of pathogens and communities studied needs to be broadened if we are to understand the ecological factors that favour dilution and how often these conditions occur in nature.

Persistence of avian haemosporidians in the wild: a case study to illustrate seasonal infection patterns in relation to host life stages

Infection patterns of avian haemosporidians result from the evolution of their associations with hosts, and can be shaped by multiple biotic factors. However, at the level of parasite species, few studies have investigated the details of the temporal dynamics of infection patterns in wild bird communities. We hereby studied a wild bird community in southern Sweden to investigate two generalist parasites (cyt b lineages PARUS1 and WW2) of the morphological species Haemoproteus majoris in their main host species (tits and warblers, respectively) to look for seasonal (spring to autumn) and age class related variation in infection patterns. For both lineages, we detected a similar temporal pattern in prevalence and infection intensity, with peak levels during the main nesting season in adults and a few weeks later in juveniles. Infections in juveniles were detected as soon as they started to be caught by mist nets, implying that they became infected when still in the nest or during the first weeks post-fledging. The initially high intensities in juveniles were followed by a significant decrease during the hatching year, emphasising the importance of studying haemosporidian infections in nestlings and fledglings. Both prevalence and infection intensity in adults increased from spring to early summer, either due to spring relapses or new infections. Both prevalence and infection intensity declined in adults at the time when independent juveniles of the respective species started to appear, suggesting that the rate of parasite withdrawal from blood exceeded the rates of new infections gained and relapses of previous infections. Prevalence in both juveniles and adults approached zero towards the end of the summer.

Patterns of avian haemosporidian infections vary with time, but not habitat, in a fragmented Neotropical landscape

Habitat loss has the potential to alter vertebrate host populations and their interactions with parasites. Theory predicts a decrease in parasite diversity due to the loss of hosts in such contexts. However, habitat loss could also increase parasite infections as a result of the arrival of new parasites or by decreasing host immune defenses. We investigated the effect of habitat loss and other habitat characteristics on avian haemosporidian infections in a community of birds within a fragmented landscape in northwest Ecuador. We estimated Plasmodium and Haemoproteus parasite infections in 504 individual birds belonging to 8 families and 18 species. We found differences in infection status among bird species, but no relationship between forest fragment characteristics and infection status was observed. We also found a temporal effect, with birds at the end of the five-month study (which ran from the end of the rainy season thru the dry season), being less infected by Plasmodium parasites than individuals sampled at the beginning. Moreover, we found a positive relationship between forest area and Culicoides abundance. Taken as a whole, these findings indicate little effect of fragment characteristics per se on infection, although additional sampling or higher infection rates would have offered more power to detect potential relationships.

Age-specific patterns of infection with haemosporidians and trypanosomes in a warbler: implications for sexual selection

Although the selective loss of individuals susceptible to disease can favor the evolution of female preference for older males, the interrelationship between age, infection, longevity, and mating success remains poorly characterized in natural populations. In a longitudinal study of 61 male common yellowthroats (Geothlypis trichas), we found that the probability of infection with hematozoa increased as males aged from 1 to 5 years. Despite a significant, negative association between infection and longevity that partially masked age-effects, the odds that a male was infected with Trypanosoma, Plasmodium, or Leucocytozoon increased 71-212% per year. Nearly 75% of males in their first breeding season were either uninfected or infected with only a single parasite, while 50% of older males were infected with at least two parasites and 16% were infected with all three. No males escaped infection after their second breeding season. Older males were also more likely to sire extra-pair young (EPY) and, as a consequence, infection with multiple parasites was associated with a fourfold increase in the odds of producing EPY. Unlike younger males, 80% of the oldest males had a history of either surviving chronic infection or recovering. Combined with previous work showing higher diversity at the major histocompatibility complex among older males, our results suggest that the song and plumage traits that signal male age in common yellowthroats also, perforce, signal resistance to parasites. By preferring older males, females may obtain good genes for disease resistance even in the absence of any effect of infection on male ornamentation.

Observations on Leucocytozoon infections in birds receiving paludrine, atebrin, and sulphamerazine

Paludrine, atebrin, and sulphamerazine neither prevented nor cured infections with Leucocytozoon simondi in ducklings, nor did they have any noticeable effect on the course of the infections. Paludrine failed to cure an established infection of Leucocytozoon sakharoffi in a crow. The extensive 'tissue stages' of these parasites probably explain the negative results.

Associations between malaria and MHC genes in a migratory songbird

Malaria parasites are a widespread and species-rich group infecting many wild populations of mammals, birds and reptiles. Studies on humans have demonstrated that genetic factors play a key role in the susceptibility and outcome of malaria infections. Until the present study, it has not been examined whether genetic variation in hosts is important for the outcome of malaria infections in natural avian populations. We investigated associations between major histocompatibility complex (MHC) genes and prevalence of three different avian malaria parasites (Haemoproteus payevskyi (GRW1), Plasmodium sp. (GRW2) and Plasmodium sp. (GRW4)) in a long-term study of great reed warblers Acrocephalus arundinaceus. We hypothesized that the MHC genes could either give full protection against a malaria infection, or confer protection against lethal malaria and direct the infection towards being milder. We found a positive association between numbers of MHC class I alleles (a measure of level of heterozygosity) and prevalence of the GRW2 parasite, suggesting the latter scenario. There was also a positive association between a specific MHC allele (B4b), previously shown to be under frequency-dependent selection in the study population, and prevalence of GRW2. These associations suggest that individuals carrying either a large number of MHC alleles or a specific MHC allele are protected against lethal malaria infections.

Survival costs of reproduction in the blue tit (Parus caeruleus): a role for blood parasites?

One of the central tenets in life-history theory is that there is a trade-off between current and future reproduction (i.e. a cost of reproduction). The mechanism for this cost of reproduction is, however, largely unknown. One hypothesis is that the high workload during reproduction compromises resistance to parasites and that the resulting increase in parasitaemia has negative effects on the prospects of future survival. Although empirical evidence for a negative relationship between reproductive effort and parasite resistance exists, the causal relationships between reproductive effort, parasite resistance and future reproduction are still unclear. We use a path analytical approach to investigate whether a change in parasite resistance (as measured by intensities of infections by the blood parasite Haemoproteus) after manipulation of reproductive effort, translates into altered survival in female blue tits. Our results show a negative relationship between reproductive effort and parasite resistance, although evident only in first-year breeders. Moreover, we found survival costs of reproduction in first-year breeders. These costs were, however, not mediated by the blood parasite studied.

Prevalence of blood parasites in European passeriform birds

Variation in the prevalence of blood parasites among species of birds has been used to test hypotheses about the effects of sexual selection and parental investment on disease resistance, and how vector abundance influences infection. However, the factors causing this variation are still poorly understood. We assessed the statistical effects of biogeographic, plumage-related and life-history traits on the prevalence of the blood parasites Plasmodium, Haemoproteus, Leucocytozoon and Trypanosoma in European passerine birds. Most of the variation in parasite prevalence occurred at low taxonomic levels. Brighter male plumage and greater host body mass were associated with higher prevalence, explaining 32% of the total variation. Male plumage brightness remained a significant factor when we controlled for phylogenetic effects. These relationships were driven primarily by simuliid-transmitted parasites (Leucocytozoon, Trypanosoma), which were more frequent in species with northern distributions. Host species with greater maximum longevity and shorter nestling periods had higher prevalences of Plasmodium; however, the effect was not stable after controlling for phylogeny using pairwise contrasts. Coevolution between hosts and parasites appears to create temporal and spatial variation that disconnects haematozoan prevalence from evolutionarily conservative life-history traits while creating some positive associations with traits that are phylogenetically labile. Clearly, ecologists should be cautious in relating patterns of variation in haematozoan prevalence to particular host traits.

Parasite mediated mortality and host immune response explain age-related differences in blood parasitism in birds

An important pattern in host-parasite assemblages is a higher intensity of parasites in juveniles than in adults, but the reasons for these differences remain obscure. Three non-mutually exclusive hypotheses have been proposed: (1) heavily parasitized juveniles die before being recruited into the adult population ('selection' hypothesis); (2) the development of an acquired immunity by the host in front of the parasite reduces the intensity of the parasite in adult hosts ('immunity' hypothesis); and (3) differences in behavior makes adults less exposed to the parasite than juveniles ('vector exposure' hypothesis). Having rejected the 'vector exposure' hypothesis in a previous study, here we tested the 'selection' and 'immunity' hypotheses in feral pigeons (Columba livia) infected by the blood parasite Haemoproteus columbae. In agreement with the 'selection' hypothesis, young (but not adult) pigeons that were highly parasitized had a lower probability of surviving until adulthood, independent of their body condition. However, selection was not strong enough to account for the observed differences in parasite intensity between age-classes, and after selection parasite intensity of survivors still remained 85% higher in juveniles than in adults. In contrast, the 'immunity' hypothesis offered a greater explanatory power. The intensity of blood parasites in young pigeons, but not in adults, decreased over time so dramatically that by the time they had become adults their intensities were indistinguishable from that typically seen in adults. Therefore, while selection against highly parasitized juveniles can contribute to some extent to a reduction in parasitism seen in the adult population, age-specific blood parasitism in feral pigeons is best explained as a transitory phase just before the host develops an effective immune response.

Role of pseudolynchia canariensis in the transmission of haemoproteus turtur from the migrant Streptopelia turtur to new bird hosts in Egypt

Pseudolynchia canariensis flies offered the naturally infected migrant dove Streptopelia turtur with Haemoproteus turtur succeeded to induce weak infection in the raised Streptopelia turtur only. Intraperitoneal, intramuscular and subcutaneous injection of their salivary glands together with intraperitoneal injection of macerated lung and liver tissues of infected doves revealed the appearance of low and moderate grade parasitaemia in S. senegallus and the raised S. turtur. Flies offered laboratory infected donor doves of low and moderate parasitaemia could transmit the parasite through all the experimental trials during the course of infection with variable degrees of parasitaemia to both doves. All attempts to transmit H. turtur to Columba livia was unsuccessful.

Bionomics and laboratory transmission of Haemoproteus columbae Kruse by Pseudolynchia canariensis Maquart (Diptera: Hippoboscidae) to two bird hosts in Egypt

Pseudolynchia canariensis succeeded to feed and survive normally on both Streptopelia senegallus and S. turtur. The feeding period, blood meal ratio and longevity of both male and female flies did not differ significantly (P > 0.05) from the corresponding values for the natural host Columba livia. Infection of S. senegallus with Haemoproteus columbae through flies bites, injection with either infected salivary glands suspension or infected macerated lung tissue of C. livia revealed a high parasitaemia levels accompanied with normal prepatent periods. However, in S. turtur low parasitaemia levels appeared after long prepatent periods when using the same course of infection with H. columbae.

Mortality in fledgling great horned owls from black fly hematophaga and leucocytozoonosis

Black fly feeding alone and in concert with Leucocytozoon spp. infection caused mortality in fledgling great horned owls (Bubo virginianus) in the Yukon, Canada 1990 to 1991. These mortalities occurred during a year of food shortage corresponding with a decline in the population of snowshoe hare (Lepus americanus), the main prey for great horned owls. We hypothesize an interaction between food availability and the consequences of host-parasite interactions.

Sex proportions of Haemoproteus blood parasites and local mate competition

Recent genetic evidence suggests that parasitic protozoa often reproduce by "selfing," defined as sexual stages from a single, clonal lineage fertilizing each other. Selfing favors production of an excess of female over male progeny. We tested whether the proportion of male gametocytes of blood parasites of the genus Haemoproteus was affected by variables that could influence the probability of selfing. Proportions of male Haemoproteus gametocytes from 11 passerine host populations were not affected by the age of the parasites' avian hosts, date in season, sex of host, intensity of host's infection, or prevalence of parasites within host populations.