Avian Malaria and Related Parasites from Resident and Migratory Birds in the Brazilian Atlantic Forest, with Description of a New Haemoproteus Species

Novel phylogenetic clade of avian Haemoproteus parasites (Haemosporida, Haemoproteidae) from Accipitridae raptors, with description of a new Haemoproteus species

Avian haemosporidian parasites (order Haemosporida, phylum Apicomplexa) are blood and tissue parasites transmitted by blood-sucking dipteran insects. Three genera (Plasmodium, Haemoproteus and Leucocytozoon) have been most often found in birds, with over 270 species described and named in avian hosts based mainly on the morphological characters of blood stages. A broad diversity of Haemoproteus parasites remains to be identified and characterized morphologically and molecularly, especially those infecting birds of prey, an underrepresented bird group in haemosporidian parasite studies. The aim of this study was to investigate and identify Haemoproteus parasites from a large sample comprising accipitriform raptors of 16 species combining morphological and new molecular protocols targeting the cytb genes of this parasite group. This study provides morphological descriptions and molecular characterizations of two Haemoproteus species, H. multivacuolatus n. sp. and H. nisi Peirce and Marquiss, 1983. Haemoproteus parasites of this group were so far found in accipitriform raptors only and might be classified into a separate subgenus or even genus. Cytb sequences of these parasites diverge by more than 15% from those of all others known avian haemosporidian genera and form a unique phylogenetic clade. This study underlines the importance of developing new diagnostic tools to detect molecularly highly divergent parasites that might be undetectable by commonly used conventional tools.

Avian haemosporidians of breeding birds in the Davis Mountains sky-islands of west Texas, USA

Avian haemosporidians are protozoan parasites transmitted by insect vectors that infect birds worldwide, negatively impacting avian fitness and survival. However, the majority of haemosporidian diversity remains undescribed. Quantifying this diversity is critical to determining parasite–host relationships and host-switching potentials of parasite lineages as climate change induces both host and vector range shifts. In this study, we conducted a community survey of avian haemosporidians found in breeding birds on the Davis Mountains sky islands in west Texas, USA. We determined parasite abundance and host associations and compared our results to data from nearby regions. A total of 265 birds were screened and infections were detected in 108 birds (40.8%). Most positive infections were identified as Haemoproteus (36.2%), followed by Plasmodium (6.8%) and Leucocytozoon (0.8%). A total of 71 haemosporidian lineages were detected of which 39 were previously undescribed. We found that regional similarity influenced shared lineages, as a higher number of lineages were shared with avian communities in the sky islands of New Mexico compared to south Texas, the Texas Gulf Coast and central Mexico. We found that migratory status of avian host did not influence parasite prevalence, but that host phylogeny is likely an important driver.

Prevalence and Diversity of Blood Parasites (Plasmodium, Leucocytozoon and Trypanosoma) in Backyard Chickens (Gallus gallus domesticus) Raised in Southern Thailand

Avian malaria and leucocytozoonosis can cause fatal diseases, whereas avian trypanosomiasis is reported to be harmless in chickens. Backyard chickens can be infected by several pathogens, including blood parasites, that may shed to industrial poultry production, with a consequently higher economic impact. This study aimed to investigate the presence of several blood parasites (Plasmodium, Leucocytozoon and Trypanosoma) in backyard chickens raised in Southern Thailand, using PCR-based detection and microscopic methods. From June 2021 to June 2022, 57 backyard chickens were sampled. Fresh thin blood smears were prepared from 11 individuals, and buffy coat smears were prepared from 55 of them. Both thin blood smears and buffy coat smears were used for microscopic analysis. Two nested PCR protocols that amplify a fragment of cytochrome b (cytb) and small subunit rRNA (SSU rRNA) genes were used to identify Haemosporida and Trypanosoma parasites, respectively. The number of positive samples was higher with the application of nested PCR than when buffy coat smears were used. Three new Plasmodium lineages (GALLUS47-49) and thirteen Leucocytozoon lineages (GALLUS50-62) were found. Trophozoites, meronts and gametocytes of Plasmodium gallinaceum (GALLUS01) were present in one thin blood smear. All thin blood smears revealed Leucocytozoon infections, but only three samples were a single infection. These three samples revealed the presence of fusiform host cell-parasite complexes, of which the morphological features resembled those of Leucocytozoon macleani (possible synonym is Leucocytozoon sabrazesi), while the cytb showed that this parasite is closely related to the lineage GALLUS06-07, described as Leucocytozoon schouteni. The Trypanosoma prevalence was 33.33%; it was present in only one of the thin blood smears, and it resembles Trypanosoma calmettei. This study showed the prevalence of a high diversity of Plasmodium (64.91%) and Leucocytozoon (89.47%) in Thai chickens. Both nested-PCR and buffy coat smear can be used as the diagnostic tool for the testing of Plasmodium, Leucocytozoon and Trypanosoma for parasitic control in backyard chickens and poultry farms. The information on the parasite species that can be found in chickens raised in Southern Thailand was also considered as the baseline information for further study.

Prevalence and genetic diversity of avian haemosporidian parasites in islands within a mega hydroelectric dam in the Brazilian Amazon

The Brazilian Amazon supports an extremely diverse avifauna and serves as the diversification center for avian malaria parasites in South America. Construction of hydroelectric dams can drive biodiversity loss by creating islands incapable of sustaining the bird communities found in intact forest sites. Besides anthropogenic actions, the presence of parasites can also influence the dynamics and structure of bird communities. Avian malaria (Plasmodium) and related haemosporidian parasites (Haemoproteus and Leucocytozoon) are a globally distributed group of protozoan parasites recovered from all major bird groups. However, no study to date has analyzed the presence of avian haemosporidian parasites in fragmented areas such as land bridge islands formed during artificial flooding following the construction of hydroelectric dams. The aim of this study is to assess the prevalence and molecular diversity of haemosporidians in bird communities inhabiting artificial islands in the area of the Balbina Hydroelectric Dam. The reservoir area covers 443,700 ha with 3546 islands on the left bank of the Uatumã River known to contain more than 400 bird species. We surveyed haemosporidian infections in blood samples collected from 445 understory birds, belonging to 53 species, 24 families, and 8 orders. Passeriformes represented 95.5% of all analyzed samples. We found a low overall Plasmodium prevalence (2.9%), with 13 positive samples (two Plasmodium elongatum and 11 Plasmodium sp.) belonging to eight lineages. Six of these lineages were previously recorded in the Amazon, whereas two of them are new. Hypocnemis cantator, the Guianan Warbling Antbird, represented 38.5% of all infected individuals, even though it represents only 5.6% of the sampled individuals. Since comparison with Plasmodium prevalence data prior to construction of Balbina is not possible, other studies in artificially flooded areas are imperative to test if anthropogenic flooding may disrupt vector-parasite relationships leading to low Plasmodium prevalence.

Haemosporidians in Non-Passerine Birds of Colombia: An Overview of the Last 20 Years of Research

The Neotropics are highly diverse in avian species. Neotropical countries contribute a large part of the estimated diversity of haemosporidian parasites reported for the planet’s tropical zones. However, sampling is limited and biased, illustrated by only 30% of the genetic records (barcodes) from non-passerines, most of them not linked to a nominal species. This paper aimed to perform the molecular and morphological characterization of the haemosporidians that infect non-passerine birds from Colombia deposited in the biological collection named “Grupo de Estudio Relación Parásito Hospedero (GERPH)”. We analyzed 1239 samples from twelve biomes and two animal care facilities. Phylogenetic relationships using barcodes and mitochondrial genomes were estimated. In addition, the reports of haemosporidian infections in non-passerine birds from the Neotropics recorded after 1978 were summarized. We reported the presence of thirteen morphological haemosporidian species, four potential new species deposited in GERPH, a host range expansion for two Plasmodium species, and a barcode sequence for Haemoproteus caprimulgi. We confirmed the species associated with 56 molecular lineages reported in other neotropical countries at the genus level. Thus, biological collections and curated databases such as MalAvi are essential to support integrative approaches demanded in modern taxonomy.

Beta diversity, prevalence, and specificity of avian haemosporidian parasites throughout the annual cycle of Chilean Elaenia (Elaenia chilensis), a Neotropical austral migrant

Migratory birds are implicated in dispersing haemosporidian parasites over great geographic distances. However, their role in sharing these vector-transmitted blood parasites with resident avian host species along their migration flyway is not well understood. We studied avian haemosporidian parasites in 10 localities where Chilean Elaenia, a long-distance Neotropical austral migrant species, spends part of its annual cycle to determine local parasite transmission among resident sympatric host species in the elaenia's distributional range across South America. We sampled 371 Chilean Elaenias and 1,818 birds representing 243 additional sympatric species from Brazilian wintering grounds to Argentinian breeding grounds. The 23 haemosporidian lineages found in Chilean Elaenias exhibited considerable variation in distribution, specialization, and turnover across the 10 avian communities in South America. Parasite lineage dissimilarity increased with geographic distance, and infection probability by Parahaemoproteus decreased in localities harbouring a more diverse haemosporidian fauna. Furthermore, blood smears from migrating Chilean Elaenias and local resident avian host species did not contain infective stages of Leucocytozoon, suggesting that transmission did not take place in the Brazilian stopover site. Our analyses confirm that this Neotropical austral migrant connects avian host communities and transports haemosporidian parasites along its distributional range in South America. However, the lack of transmissive stages at stopover site and the infrequent parasite lineage sharing between migratory host populations and residents at breeding and wintering grounds suggest that Chilean Elaenias do not play a significant role in dispersing haemosporidian parasites, nor do they influence local transmission across South America.

Host life-history traits predict haemosporidian parasite prevalence in tanagers (Aves: Thraupidae)

Vector-borne parasites are important ecological drivers influencing life-history evolution in birds by increasing host mortality or susceptibility to new diseases. Therefore, understanding why vulnerability to infection varies within a host clade is a crucial task for conservation biology and for understanding macroecological life-history patterns. Here, we studied the relationship of avian life-history traits and climate on the prevalence of Plasmodium and Parahaemoproteus parasites. We sampled 3569 individual birds belonging to 53 species of the family Thraupidae. Individuals were captured from 2007 to 2018 at 92 locations. We created 2 phylogenetic generalized least-squares models with Plasmodium and Parahaemoproteus prevalence as our response variables, and with the following predictor variables: climate PC1, climate PC2, body size, mixed-species flock participation, incubation period, migration, nest height, foraging height, forest cover, and diet. We found that Parahaemoproteus and Plasmodium prevalence was higher in species inhabiting open habitats. Tanager species with longer incubation periods had higher Parahaemoproteus prevalence as well, and we hypothesize that these longer incubation periods overlap with maximum vector abundances, resulting in a higher probability of infection among adult hosts during their incubation period and among chicks. Lastly, we found that Plasmodium prevalence was higher in species without migratory behaviour, with mixed-species flock participation, and with an omnivorous or animal-derived diet. We discuss the consequences of higher infection prevalence in relation to life-history traits in tanagers.

Keys to the avian Haemoproteus parasites (Haemosporida, Haemoproteidae)

Background

Haemoproteus is a sister genus to malaria parasites (Plasmodium), which both belong to the order Haemosporida (Apicomplexa). Parasites of both genera are flourishing in birds, however, Haemoproteus species are noticeably less investigated. This is unfortunate because knowledge about close relatives of malaria pathogens is important for better understanding the evolutionary origin and basic biological features of the entire group of haemosporidian infections. Moreover, recent findings show that Haemoproteus species can cause severe damage of various bird organs due to megalomeronts and other exo-erythrocytic stages. These haemosporidians are remarkably diverse, but remain neglected partly due to difficulties in species identification. Hundreds of Haemoproteus genetic lineages have been reported in birds, and numerous new lineages are found each year, but most remain unidentified to the species level. Numerous new Haemoproteus pathogens were described during the past 20 years. However, keys for their identification are absent. Identification of Haemoproteus species remains a difficult task and is an obstacle for better understanding of the distribution and epidemiology of these parasites. This study aimed to develop comprehensive keys for the identification of described avian Haemoproteus species using morphological features of their blood stages (gametocytes).

Methods

Type and voucher preparations of avian Haemoproteus species were accessed in museums in Europe, Australia and the USA. Gametocytes of most described species were examined, and these data formed a background for this study. The data also were considered from published articles containing parasite species descriptions. The method of dichotomous keys was applied. The most difficult steps in the keys were accompanied with references to the corresponding parasite pictures.

Results

In all, 201 published articles were included in this review. Morphological diagnostic features of gametocytes of all described Haemoproteus species were analysed and compared. Illustrated keys for identification of these parasite species were developed. Available information about the molecular characterization of Haemoproteus parasites was provided.

Conclusion

This review shows that 177 described species of avian Haemoproteus can be distinguished and identified in blood films using morphological characters of their gametocytes and host cells. These species were incorporated in the keys. Information about possible morphologically cryptic parasites was provided. Molecular markers are available for only 42% of the described Haemoproteus parasites, calling for researchers to fill this gap.

Haemosporidian taxonomic composition, network centrality and partner fidelity between resident and migratory avian hosts

Migration can modify interaction dynamics between parasites and their hosts with migrant hosts able to disperse parasites and impact local community transmission. Thus, studying the relationships among migratory hosts and their parasites is fundamental to elucidate how migration shapes host-parasite interactions. Avian haemosporidians are some of the most prevalent and diverse group of wildlife parasites and are also widely studied as models in ecological and evolutionary research. Here, we contrast partner fidelity, network centrality and parasite taxonomic composition among resident and non-resident avian hosts using presence/absence data on haemosporidians parasitic in South American birds as study model. We ran multilevel Bayesian models to assess the role of migration in determining partner fidelity (i.e., normalized degree) and centrality (i.e., weighted closeness) in host-parasite networks of avian hosts and their respective haemosporidian parasites. In addition, to evaluate parasite taxonomic composition, we performed permutational multivariate analyses of variance to quantify dissimilarity in haemosporidian lineages infecting different host migratory categories. We observed similar partner fidelity and parasite taxonomic composition among resident and migratory hosts. Conversely, we demonstrate that migratory hosts play a more central role in host-parasite networks than residents. However, when evaluating partially and fully migratory hosts separately, we observed that only partially migratory species presented higher network centrality when compared to resident birds. Therefore, migration does not lead to differences in both partner fidelity and parasite taxonomic composition. However, migratory behavior is positively associated with network centrality, indicating migratory hosts play more important roles in shaping host-parasite interactions and influence local transmission.

Description of Haemoproteus asymmetricus n. sp. (Haemoproteidae), with remarks on predictability of the DNA haplotype networks in haemosporidian parasite taxonomy research

Haemoproteus species (Haemosporida, Haemoproteidae) are cosmopolitan blood parasites, which have been neglected for over 100-years, but attracted attention recently due to reports of severe and even lethal haemoproteosis in birds and vectors. Approximately 150 species of avian Haemoproteus have been described and named, but molecular data suggest that hundreds of independently evolving molecular lineages might occur, indicating the existence of a remarkable undescribed species diversity. It is timely to develop a methodology, which allow the application of available genetic data in taxonomy of haemosporidians on species levels. This study aimed to test a hypothesis suggesting that DNA haplotype networks might aid in targeting genetically distinct, but still undescribed parasites, and might be used to direct taxonomic studies on haemosporidian species levels. Mainly, we tested a prediction that the lineage hTUPHI01, a common Haemoproteus parasite of Turdus philomelos, might be a new species, which is morphologically similar and genetically closely related to the parasites of Haemoproteus minutus group. Blood samples of T. philomelos naturally infected with this parasite lineage were collected and studied using microscopic examination of blood films and PCR-based methods. Haemoproteus asymmetricus n. sp. was found in this bird, described and characterised molecularly using partial cytochrome b (cytb) sequences. The new species shared some features with parasites of the H. minutus group, as was predicted by the DNA haplotype network. Due to the visualisation of closely related lineages as well as the evaluation of their host and geographic distributions, DNA haplotype networks can be recommended as the helpful methodology, able to direct and speed practical work on parasite species taxonomy and pathogen biodiversity. The combined molecular phylogenetic and morphological approaches showed that the well-supported clades in Bayesian phylogenetic trees based on the partial cytb gene sequences contain morphologically remarkably different Haemoproteus parasite species, which however, share some basic biological features. Phylogenetic analysis can be used for prediction of these basic features in still undescribed parasites. This study calls for further fusion of advanced molecular and microscopy approaches for better understanding haemosporidian parasite biology.

Characterization of the Plasmodium and Haemoproteus parasite community in temperate-tropical birds during spring migration

Animal movements, especially avian migration, can be a mechanism for the large-scale dispersal and geographic range expansion of parasites. The host-parasite relationships among birds during migration have yet to be fully explored. We characterized the haemosporidian parasite lineages in passerines during spring migration on the Texas coast of the Gulf of Mexico, and identified associations among wintering origin (US, Central America, South America) and foraging height (canopy, understory, ground) and infection status. We examined 743 samples representing 52 species of 10 families over six years, 2014-2019. We used PCR and DNA sequencing of the haemosporidian cytB gene from avian blood samples to determine infection status with the genera Plasmodium and Haemoproteus and characterize the lineages of blood parasites. We found an overall haemosporidian infection prevalence of 48.4% among neotropical migrant and Texas wintering birds. Among families, Icterids had the highest prevalence (75%, 24 individuals, 4 species sampled) whereas Parulids had the lowest prevalence (38.4%, 177 individuals, 18 species sampled). Among infected birds, Plasmodium spp. infections were more common than Haemoproteus spp. infections in species that winter in Central America compared to those that winter in the US or South America. Similarly, among infected birds, Plasmodium spp. infections were more common than Haemoproteus spp. infections in species that forage on the ground or in the understory compared to those that forage in the canopy. Infected birds harbored 65 different haemosporidian lineages (71% Plasmodium; 29% Haemoproteus) of which 17 lineages have never previously been reported and six lineages were documented for the first time in North America, having been previously detected only in Central or South America. These data are consistent with the premise that intercontinental parasite dispersal may be facilitated by passerine birds. Future studies focused on surveillance, the probability of establishment of parasite lineages, and the use of individual bird tracking methods to understand infection dispersion over time will allow a more comprehensive understanding of changing avian host-haemosporidian relationships.

Assessing Diversity, Plasmodium Infection and Blood Meal Sources in Mosquitoes (Diptera: Culicidae) from a Brazilian Zoological Park with Avian Malaria Transmission

Avian malaria parasites are widespread parasites transmitted by Culicidae insects belonging to different genera. Even though several studies have been conducted recently, there is still a lack of information about potential vectors of Plasmodium parasites, especially in Neotropical regions. Former studies with free-living and captive animals in São Paulo Zoo showed the presence of several Plasmodium and Haemoproteus species. In 2015, a pilot study was conducted at the zoo to collect mosquitoes in order to find out (i) which species of Culicidae are present in the study area, (ii) what are their blood meal sources, and (iii) to which Plasmodium species might they be potential vectors. Mosquitoes were morphologically and molecularly identified. Blood meal source and haemosporidian DNA were identified using molecular protocols. A total of 25 Culicidae species were identified, and 6 of them were positive for Plasmodium/Haemoproteus DNA. Ten mosquito species had their source of blood meal identified, which were mainly birds, including some species that were positive for haemosporidian parasites in the former study mentioned. This study allowed us to expand the list of potential vectors of avian malaria parasites and to improve our knowledge of the evolutionary and ecological relationships between the highly diverse communities of birds, parasites, and vectors present at São Paulo Zoo.