A molecular phylogeny of malarial parasites recovered from cytochrome b gene sequences

Unresolved haemosporidia of the Australian skink, Egernia stokesii

The Australian skink Egernia stokesii had been recognised as a host of two species of Plasmodium, Plasmodium mackerrasae and P. circularis; nevertheless, molecular data are available for only a single haemosporidian species of this host. Its sequences are labelled as "Plasmodium sp." or "Plasmodium mackerrasae", but morphological characteristics of this isolate are unavailable. Phylogenetic analyses of these sequences placed them into the clade of the genus Haemocystidium. In this study, blood samples of six E. stokesii were analysed by both, molecular and microscopic methods to clarify the haemosporidia of this lizard. Application of these approaches offered discordant results. Whereas sequence analysis clustered our isolates with lizard species of Haemocystidium, morphology of blood stages is more akin to Plasmodium than Haemocystidium. However, limited sampling, indistinguishable nuclei/merozoites and risk of possible hidden presence of mixed infection prevent reliable species identification of detected parasites or their description as new species of Haemocystidium.

A new long-read mitochondrial-genome protocol (PacBio HiFi) for haemosporidian parasites: a tool for population and biodiversity studies

BACKGROUND

Studies on haemosporidian diversity, including origin of human malaria parasites, malaria's zoonotic dynamic, and regional biodiversity patterns, have used target gene approaches. However, current methods have a trade-off between scalability and data quality. Here, a long-read Next-Generation Sequencing protocol using PacBio HiFi is presented. The data processing is supported by a pipeline that uses machine-learning for analysing the reads.

METHODS

A set of primers was designed to target approximately 6 kb, almost the entire length of the haemosporidian mitochondrial genome. Amplicons from different samples were multiplexed in an SMRTbell® library preparation. A pipeline (HmtG-PacBio Pipeline) to process the reads is also provided; it integrates multiple sequence alignments, a machine-learning algorithm that uses modified variational autoencoders, and a clustering method to identify the mitochondrial haplotypes/species in a sample. Although 192 specimens could be studied simultaneously, a pilot experiment with 15 specimens is presented, including in silico experiments where multiple data combinations were tested.

RESULTS

The primers amplified various haemosporidian parasite genomes and yielded high-quality mt genome sequences. This new protocol allowed the detection and characterization of mixed infections and co-infections in the samples. The machine-learning approach converged into reproducible haplotypes with a low error rate, averaging 0.2% per read (minimum of 0.03% and maximum of 0.46%). The minimum recommended coverage per haplotype is 30X based on the detected error rates. The pipeline facilitates inspecting the data, including a local blast against a file of provided mitochondrial sequences that the researcher can customize.

CONCLUSIONS

This is not a diagnostic approach but a high-throughput method to study haemosporidian sequence assemblages and perform genotyping by targeting the mitochondrial genome. Accordingly, the methodology allowed for examining specimens with multiple infections and co-infections of different haemosporidian parasites. The pipeline enables data quality assessment and comparison of the haplotypes obtained to those from previous studies. Although a single locus approach, whole mitochondrial data provide high-quality information to characterize species pools of haemosporidian parasites.

Raising the bar: genus-specific nested PCR improves detection and lineage identification of avian haemosporidian parasites

Avian haemosporidian parasites are useful model organisms to study the ecology and evolution of parasite-host interactions due to their global distribution and extensive biodiversity. Detection of these parasites has evolved from microscopic examination to PCR-based methods, with the mitochondrial cytochrome b gene serving as barcoding region. However, standard PCR protocols used for screening and identification purposes have limitations in detecting mixed infections and generating phylogenetically informative data due to short amplicon lengths. To address these issues, we developed a novel genus-specific nested PCR protocol targeting avian haemosporidian parasites. The protocol underwent rigorous testing utilizing a large dataset comprising blood samples from Malagasy birds of three distinct Passeriformes families. Furthermore, validation was done by examining smaller datasets in two other laboratories employing divergent master mixes and different bird species. Comparative analyses were conducted between the outcomes of the novel PCR protocol and those obtained through the widely used standard nested PCR method. The novel protocol enables specific identification of Plasmodium, Haemoproteus (Parahaemoproteus), and Leucocytozoon parasites. The analyses demonstrated comparable sensitivity to the standard nested PCR with notable improvements in detecting mixed infections. In addition, phylogenetic resolution is improved by amplification of longer fragments, leading to a better understanding of the haemosporidian biodiversity and evolution. Overall, the novel protocol represents a valuable addition to avian haemosporidian detection methodologies, facilitating comprehensive studies on parasite ecology, epidemiology, and evolution.

Recolonization of secondary forests by a locally extinct Caribbean anole through the lens of range expansion theory

Disturbance and recovery dynamics are characteristic features of many ecosystems. Disturbance dynamics are widely studied in ecology and conservation biology. Still, we know less about the ecological processes that drive ecosystem recovery. The ecological processes that mediate ecosystem recovery stand at the intersection of many theoretical frameworks. Range expansion theory is one of these complementary frameworks that can provide unique insights into the population-level processes that mediate ecosystem recovery, particularly fauna recolonization. Although the biodiversity patterns that follow the fauna recolonization of recovering forests have been well described in the literature, the ecological processes at the population level that drive these patterns remain conspicuously unknown. In this study, we tested three fundamental predictions of range expansion theory during the recolonization of recovering forests in Puerto Rico by a shade specialist anole, Anolis gundlachi. Range expansion theory predicts that individuals at the early stages of recolonization (i.e., younger forests) would have a high prevalence of dispersive traits, experience less density dependence, and suffer less parasitism. To test these predictions, we conducted a chronosequence study applying space-for-time substitution where we compared phenotypic traits (i.e., body size, body condition, and relative limb size), population density, population growth rates, and Plasmodium parasitism rates among lizard populations living in young (<30 years), mid (~40-70 years), and old-growth forests (>75 years). Lizard populations in younger forests had lower densities, higher population growth rates, and lower rates of Plasmodium parasitism compared with old-growth forests. Still, while we found that individuals had larger body sizes, and longer forelimbs in young forests in one site, this result was not consistent among sites. This suggests a potential trade-off between the traits that provide a dispersal advantage during the initial stages of recolonization and those that are advantageous to establish in novel environmental conditions. Overall, our study emphasizes the suitability of range expansion theory to describe fauna recolonization but also highlights that the ecological processes that drive recolonization are time-dependent, complex, and nuanced.

Zoonotic simian malaria parasites in free-ranging Macaca fascicularis macaques and human malaria patients in Thailand, with a note on genetic characterization of recent isolates

Despite the natural occurrences of human infections by Plasmodium knowlesi, P. cynomolgi, P. inui, and P. fieldi in Thailand, investigating the prevalence and genetic diversity of the zoonotic simian malaria parasites in macaque populations has been limited to certain areas. To address this gap, a total of 560 long-tailed macaques (Macaca fascicularis) and 20 southern pig-tailed macaques (M. nemestrina) were captured from 15 locations across 10 provinces throughout Thailand between 2018 and 2021 for investigation of malaria, as were 15 human samples residing in two simian-malaria endemic provinces, namely Songkhla and Satun, who exhibited malaria-like symptoms. Using PCR techniques targeting the mitochondrial cytb and cox1 genes coupled with DNA sequencing, 40 long-tailed macaques inhabiting five locations had mono-infections with one of the three simian malaria species. Most of the positive cases of macaque were infected with P. inui (32/40), while infections with P. cynomolgi (6/40) and P. knowlesi (2/40) were less common and confined to specific macaque populations. Interestingly, all 15 human cases were mono-infected with P. knowlesi, with one of them residing in an area with two P. knowlesi-infected macaques. Nucleotide sequence analysis showed a high level of genetic diversity in P. inui, while P. cynomolgi and P. knowlesi displayed limited genetic diversity. Phylogenetic and haplotype network analyses revealed that P. inui in this study was closely related to simian and Anopheles isolates from Peninsular Malaysia, while P. cynomolgi clustered with simian and human isolates from Asian countries. P. knowlesi, which was found in both macaques and humans in this study, was closely related to isolates from macaques, humans, and An. hackeri in Peninsular Malaysia, suggesting a sylvatic transmission cycle extending across these endemic regions. This study highlights the current hotspots for zoonotic simian malaria and sheds light on the genetic characteristics of recent isolates in both macaques and human residents in Thailand.

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.

Survey of phlebotomine sand fly fauna in a public Zoo in Brazil: Species diversity, seasonality, and host variety

Leishmaniasis is a dynamic disease in which transmission conditions change due to environmental and human behavioral factors. Epidemiological analyses have shown modifications in the spread profile and growing urbanization of the disease, justifying the expansion of endemic areas and increasing number of cases in dogs and humans. In the city of Belo Horizonte, located in the southeastern state of Minas Gerais (Brazil), visceral leishmaniasis (VL) is endemic, with a typical urban transmission pattern, but with different regional prevalence. This study was conducted at the Zoo of the Foundation of Municipal Parks and Zoobotany of Belo Horizonte (FPMZB-BH), located in the Pampulha region, which is among the areas most severely affected by VL. This study aimed to determine the taxonomic diversity of native phlebotomine sand flies (Diptera: Psychodidae), identify climatic variables that potentially affect the phenology of these insects, and determine the blood meal sources for female phlebotomine sand flies. To achieve this, 10 mammal enclosures in the zoo were selected using the presence of possible leishmaniasis reservoirs as a selection criterion, and sampled using light traps between August 2019 and August 2021. A total of 6034 phlebotomine sand flies were collected, indicating nine species, with Lutzomyia longipalpis being the very abundant species (65.35% of the total). Of the 108 engorged phlebotomine collected females, seven samples (6.5%) were positive for blood meals from humans, marsupials, canids, and birds. Relative humidity and rainfall increased the phenology of phlebotomine sand flies, with population increases in the hottest and wettest months. The data obtained will provide guidelines for competent health agencies to implement vector control measures to reduce the risk of leishmaniasis transmission in the FPMZB-BH.

Origin and diversity of malaria parasites and other Haemosporida

Symbionts, including parasites, are ubiquitous in all world ecosystems. Understanding the diversity of symbiont species addresses diverse questions, from the origin of infectious diseases to inferring processes shaping regional biotas. Here, we review the current approaches to studying Haemosporida's species diversity and evolutionary history. Despite the solid knowledge of species linked to diseases, such as the agents of human malaria, studies on haemosporidian phylogeny, diversity, ecology, and evolution are still limited. The available data, however, indicate that Haemosporida is an extraordinarily diverse and cosmopolitan clade of symbionts. Furthermore, this clade seems to have originated with their vertebrate hosts, particularly birds, as part of complex community level processes that we are still characterizing.

Molecular Investigation Confirms Myotis Genus Bats as Common Hosts of Polychromophilus in Brazil

Plasmodium spp. and some other blood parasites belonging to the order Haemosporida are the focus of many epidemiological studies worldwide. However, haemosporidian parasites from wild animals are largely neglected in scientific research. For example, Polychromophilus parasites, which are exclusive to bats, are described in Europe, Asia, Africa, and Oceania, but little is known about their presence and genetic diversity in the New World. In this study, 224 samples of bats from remaining fragments of the Atlantic Forest and Pantanal biomes, as well as urbanized areas in southern and southeastern Brazil, were analyzed for the presence of haemosporidian parasites by PCR of the mitochondrial gene that encodes cytochrome b (cytb). The PCR fragments of the positive samples were sequenced and analyzed by the Bayesian inference method to reconstruct the phylogenetic relationships between Polychromophilus parasites from bats in Brazil and other countries. Sequences from Brazilian lineages of Polychromophilus were recovered in a clade with sequences from Polychromophilus murinus and close to the one Polychromophilus sequence obtained in Panama, the only available sequence for the American continent. This clade was restricted to bats of the family Vespertilionidae and distinct from Polychromophilus melanipherus, a parasite species mainly found in bats of the family Miniopteridae. The detection of Polychromophilus and the genetic proximity to P. murinus were further confirmed with the amplification of two other genes (clpc and asl). We also found a Haemosporida parasite sequence in a sample of Noctilio albiventris collected in the Pantanal biome, which presents phylogenetic proximity with avian Haemoproteus sequences. Morphological and molecular studies are still needed to conclude and describe the Polychromophilus species in Brazilian Myotis bats in more detail and to confirm Haemoproteus parasites in bats. Nevertheless, these molecular results in Brazilian bats confirm the importance of studying these neglected genera.

Non-invasive investigation of Polychromophilus parasite infections in bat populations in Serbia using bat flies

BACKGROUND

Haemosporidian parasites of the genus Polychromophilus infect bats worldwide. They are vectored by obligate ectoparasitic bat flies of the family Nycteribiidae. Despite their global distribution, only five Polychromophilus morphospecies have been described to date. The two predominant species, Polychromophilus melanipherus and Polychromophilus murinus, are broadly distributed and mainly infect miniopterid and vespertilionid bats, respectively. In areas where species from different bat families aggregate together, the infection dynamics and ability of either Polychromophilus species to infect other host families is poorly characterized.

METHODS

We collected 215 bat flies from two bat species, Miniopterus schreibersii and Rhinolophus ferrumequinum, which sometimes form mixed clusters in Serbia. Miniopterus schreibersii is known to be frequently infected with P. melanipherus, whereas R. ferrumequinum has been observed to be incidentally infected with both Polychromophilus species. All flies were screened for Polychromophilus infections using a PCR targeting the haemosporidian cytb gene. Positive samples were subsequently sequenced for 579 bp of cytochrome b (cytb) and 945 bp of cytochrome oxidase subunit 1 (cox1).

RESULTS

Polychromophilus melanipherus DNA was detected at six out of nine sampling locations and in all three examined bat fly species collected from M. schreibersii (Nycteribia schmidlii, n = 21; Penicillidia conspicua, n = 8; Penicillidia dufourii, n = 3). Four and five haplotypes were found for cytb and cox1, respectively. Evidence for multiple Polychromophilus haplotypes was found in 15 individual flies. These results point to a high diversity of P. melanipherus parasites in Miniopterus hosts and efficient transmission throughout the study area. A single Phthiridium biarticulatum bat fly collected from R. ferrumequinum screened positive for P. melanipherus, but only yielded a partial cox1 sequence fragment. Nevertheless, this result suggests that secondary hosts (both bat and fly species) are regularly confronted with this parasite.

CONCLUSIONS

The results of this study provide new insights into the prevalence and distribution of Polychromophilus parasites in European bats and their nycteribiid vectors. The use of bat flies for the non-invasive investigation of Polychromophilus infections in bat populations has proven to be efficient and thus represents an alternative for large-scale studies of infections in bat populations without the need to invasively collect blood from bats.

Myzomyia and Pyretophorus series of Anopheles mosquitoes acting as probable vectors of the goat malaria parasite Plasmodium caprae in Thailand

Unlike malaria parasites in humans, non-human primates, rodents, and birds, ungulate malaria parasites and their vectors have received little attention. As a result, understanding of the hosts, vectors, and biology of ungulate malaria parasites has remained limited. In this study, we aimed to identify the vectors of the goat malaria parasite Plasmodium caprae. A total of 1019 anopheline and 133 non-anopheline mosquitoes were collected from goat farms in Thailand, where P. caprae-infected goats were discovered. Anopheline mosquitoes were identified using molecular biological methods that target the cytochrome c oxidase subunit 1 (cox1), the cytochrome c oxidase subunit 2 (cox2) genes, and the internal transcribed spacer 2 (ITS2) region. Pool and individual mosquitoes were tested for P. caprae using the head-thorax parts that contain the salivary glands, with primers targeting three genetic markers including cytochrome b, cytochrome c oxidase subunit 1, and 18S small subunit ribosomal RNA genes. Additionally, goat blood samples were collected concurrently with mosquito surveys and screened to determine the status of malaria infection. This study revealed nine mosquito species belonging to six groups on goat farms, including Hyrcanus, Barbirostris, Subpictus, Funestus, Tessellatus, and Annularis. The DNA of P. caprae was detected in Anopheles subpictus and Anopheles aconitus. This is the first time An. subpictus and An. aconitus have been implicated as probable vectors of P. caprae.

Detection and molecular identification of blood parasites in rodents captured from urban areas of southern Sarawak, Malaysian Borneo

BACKGROUND

Rodent species are well known for their potential as hosts and reservoirs for various zoonotic diseases. Studies on blood parasite infection in small mammals focused on urban cities in Peninsular Malaysia and have been conducted over the years. In contrast, there are information gaps related to molecular detection of blood parasites in urban areas of Sarawak that are associated with veterinary importance and zoonotic spillover potential. Increasing prevalence and transmission of blood parasite diseases is the most crucial public health issue, particularly in developing urban areas of Sarawak. Therefore, molecular identification studies were performed to determine and identify the blood parasites infecting rodents.

METHODS

A total of 40 rodent blood samples were analysed for blood parasite infection and a combined approach using polymerase chain reaction-based technique, and traditional microscopic examination (blood smear test) was conducted. 18s rRNA (Plasmodium spp.) and cytochrome b (Hepatocystis spp.) gene marker were used to identify the blood parasites.

RESULTS

Note that 67.5% (n = 27) blood samples were tested negative for blood parasites, while 32.5% (n = 13) blood samples collected were infected with at least one protozoan parasite. Out of 13 samples, 69.2% (n = 9) were detected with Hepatocystis sp., while 15.4% (n = 2) were positive with Hepatozoon ophisauri. Two individuals had multiple infections from both species. No Plasmodium spp. have been detected throughout this study using universal primer (targeted Plasmodium spp.); however, different parasite species which were H. ophisauri were detected.

CONCLUSION

Although there is no evidence of human infection from H. ophisauri and Hepatocystis sp. detected from the study, the data show the host species are heavily infected, and the information is essential for future prevention of zoonotic outbreaks and surveillance programmes. Therefore, it is suggested that the surveillance programmes should be incorporated in targeted areas with a high risk of disease emergence.

A long-term field study on mosquito vectors of avian malaria parasites in Japan

Avian malaria is a mosquito-borne disease of birds caused by avian Plasmodium spp. in worldwide scale. Some naïve birds show serious symptoms which can result in death. Surveillance of vectors and parasites are important to understand and control this disease. Although avian malaria has been found in Japan, detailed prevalence and dynamics remained understudied. We aimed to observe annual changes in the abundance of mosquitoes and the prevalence of avian Plasmodium parasites in Japan. Mosquitoes were collected using dry ice traps over a 10-year period, at a fixed research area located in Kanagawa prefecture. Collected mosquitoes were investigated for the species composition, population size and prevalence of avian Plasmodium by PCR. Mosquitoes belonging to 13 species in 7 genera were collected (n=8,965). The dominant species were Aedes (Ae.) albopictus and Culex (Cx.) pipiens group (gr.). Seven avian Plasmodium lineages, all of which were previously known, were detected from Cx. pipiens gr., Ae. albopictus, and Tripteroides bambusa. Three genetic lineages were dominant and were probably transmitted by Cx. pipiens gr. whose could be the primary vector of these parasites. Annual variations in the seasonal prevalence of mosquitoes and avian Plasmodium were revealed for the first time during recent 10 years in Japan. Namely, avian Plasmodium occurrence in the vector population peaked often in June to July and September to October when the density of the vector population was presumably high enough for the transmission of avian Plasmodium upon appearance of infected birds.

A new haemosporidian parasite from the Red-legged Seriema Cariama cristata (Cariamiformes, Cariamidae)

Haemoproteids (Haemosporida, Haemoproteidae) are a diverse group of avian blood parasites that are transmitted by hematophagous dipterans. In this study, we describe Haemoproteus pulcher sp. nov. from a Red-legged Seriema (Cariama cristata) in southeast Brazil. Analysis of the mitochondrial cytb gene indicates this parasite is closely related to Haemoproteus catharti (from Turkey Vulture, Cathartes aura) and the unidentified haemosporidian lineages PSOOCH01 (from Pale-winged Trumpeter, Psophia leucoptera) and MYCAME08 (from Wood Stork, Mycteria americana). This group of parasites appears to represent an evolutionary lineage that is distinct from other Haemoproteus spp., being instead more closely related to Haemocystidium spp. (from reptiles), Plasmodium spp. (from reptiles, birds, and mammals) and other mammal-infecting haemosporidians (Nycteria, Polychromophilus, and Hepatocystis). Current evidence suggests that parasites of this newly discovered evolutionary lineage may be endemic to the Americas, but further studies are necessary to clarify their taxonomy, life cycle, vectors, hosts, geographic distribution and host health effects. Additionally, it should be borne in mind that some PCR protocols targeting the cytb gene might not reliably detect H. pulcher due to low primer affinity.

Myzorhynchus series of Anopheles mosquitoes as potential vectors of Plasmodium bubalis in Thailand

Ungulate malaria parasites and their vectors are among the least studied when compared to other medically important species. As a result, a thorough understanding of ungulate malaria parasites, hosts, and mosquito vectors has been lacking, necessitating additional research efforts. This study aimed to identify the vector(s) of Plasmodium bubalis. A total of 187 female mosquitoes (133 Anopheles spp., 24 Culex spp., 24 Aedes spp., and 6 Mansonia spp. collected from a buffalo farm in Thailand where concurrently collected water buffalo samples were examined and we found only Anopheles spp. samples were P. bubalis positive. Molecular identification of anopheline mosquito species was conducted by sequencing of the PCR products targeting cytochrome c oxidase subunit 1 (cox1), cytochrome c oxidase subunit 2 (cox2), and internal transcribed spacer 2 (ITS2) markers. We observed 5 distinct groups of anopheline mosquitoes: Barbirostris, Hyrcanus, Ludlowae, Funestus, and Jamesii groups. The Barbirostris group (Anopheles wejchoochotei or Anopheles campestris) and the Hyrcanus group (Anopheles peditaeniatus) were positive for P. bubalis. Thus, for the first time, our study implicated these anopheline mosquito species as probable vectors of P. bubalis in Thailand.

Animal trait variation at the within-individual level: erythrocyte size variation and malaria infection in a tropical lizard

High levels of within-individual variation (WIV) in reiterative components in plants such as leaves, flowers, and fruits have been shown to increase individual fitness by multiple mechanisms including mediating interactions with natural enemies. This relationship between WIV and fitness has been studied almost exclusively in plant systems. While animals do not exhibit conspicuous reiterative components, they have traits that can vary at the individual level such as erythrocyte size. It is currently unknown if WIV in animals can influence individual fitness by mediating the outcome of interactions with natural enemies as it has been shown in plants. To address this issue, we tested for a relationship between WIV in erythrocyte size, hemoparasite infection status, and body condition (a proxy for fitness) in a Caribbean anole lizard. We quantified the coefficient of variation of adult erythrocytes size in $n = 95$ infected and $n = 107$ non-infected lizards. We found higher degrees of erythrocyte size variation in infected lizards than in non-infected individuals. However, we found no significant relationship between infection status or erythrocyte size variation, and lizard body condition. These results suggest that higher WIV in erythrocyte size in infected lizards is not necessarily adaptive but likely a consequence of the host response to infection. Many hemoparasites destroy their host cells as part of their life cycle. To compensate, the host lizard may respond by increasing production of erythrocytes resulting in higher WIV. Our results emphasize the need to better understand the role of within-animal variation as a neglected driver or consequence of ecological and evolutionary interactions.

Avian haemosporidian parasites of accipitriform raptors

Background

The order Accipitriformes comprises the largest group of birds of prey with 260 species in four families. So far, 21 haemosporidian parasite species have been described from or reported to occur in accipitriform birds. Only five of these parasite species have been characterized molecular genetically. The first part of this study involved molecular genetic screening of accipitriform raptors from Austria and Bosnia-Herzegovina and the first chromogenic in situ hybridization approach targeting parasites in this host group. The aim of the second part of this study was to summarize the CytB sequence data of haemosporidian parasites from accipitriform raptors and to visualize the geographic and host distribution of the lineages.

Methods

Blood and tissue samples of 183 accipitriform raptors from Austria and Bosnia-Herzegovina were screened for Plasmodium, Haemoproteus and Leucocytozoon parasites by nested PCR, and tissue samples of 23 PCR-positive birds were subjected to chromogenic in situ hybridization using genus-specific probes targeting the parasites’ 18S rRNAs. All published CytB sequence data from accipitriform raptors were analysed, phylogenetic trees were calculated, and DNA haplotype network analyses were performed with sequences from clades featuring multiple lineages detected in this host group.

Results

Of the 183 raptors from Austria and Bosnia-Herzegovina screened by PCR and sequencing, 80 individuals (44%) were infected with haemosporidian parasites. Among the 39 CytB lineages detected, 18 were found for the first time in the present study. The chromogenic in situ hybridization revealed exo-erythrocytic tissue stages of Leucocytozoon parasites belonging to the Leucocytozoon toddi species group in the kidneys of 14 infected birds. The total number of CytB lineages recorded in accipitriform birds worldwide was 57 for Leucocytozoon, 25 for Plasmodium, and 21 for Haemoproteus.

Conclusion

The analysis of the DNA haplotype networks allowed identifying numerous distinct groups of lineages, which have not yet been linked to morphospecies, and many of them likely belong to yet undescribed parasite species. Tissue stages of Leucocytozoon parasites developing in accipitriform raptors were discovered and described. The majority of Leucocytozoon and Haemoproteus lineages are specific to this host group, but most Plasmodium lineages were found in birds of other orders. This might indicate local transmission from birds kept at the same facilities (raptor rescue centres and zoos), likely resulting in abortive infections. To clarify the taxonomic and systematic problems, combined morphological and molecular genetic analyses on a wider range of accipitriform host species are needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-04019-z.

The vectors of Plasmodium knowlesi and other simian malarias Southeast Asia: challenges in malaria elimination

Plasmodium knowlesi, a simian malaria parasite of great public health concern has been reported from most countries in Southeast Asia and exported to various countries around the world. Currently P. knowlesi is the predominant species infecting humans in Malaysia. Besides this species, other simian malaria parasites such as P. cynomolgi and P. inui are also infecting humans in the region. The vectors of P. knowlesi and other Asian simian malarias belong to the Leucosphyrus Group of Anopheles mosquitoes which are generally forest dwelling species. Continual deforestation has resulted in these species moving into forest fringes, farms, plantations and human settlements along with their macaque hosts. Limited studies have shown that mosquito vectors are attracted to both humans and macaque hosts, preferring to bite outdoors and in the early part of the night. We here review the current status of simian malaria vectors and their parasites, knowledge of vector competence from experimental infections and discuss possible vector control measures. The challenges encountered in simian malaria elimination are also discussed. We highlight key knowledge gaps on vector distribution and ecology that may impede effective control strategies.

Plasmodium ouropretensis, n. sp., a new case of non-erythrocytic species within lizard malaria parasites

Delimiting and describing Plasmodium species in reptiles remains a pressing problem in Haemosporida taxonomy. The few morphological characters used can overlap, and the significance of some life-history traits is not fully understood. Morphologically identical lizard Plasmodium forms have been reported infecting different cell types (red and white blood cells) in the same host and have been considered the same species. An example is Plasmodium tropiduri tropiduri, a species known to infect erythrocytes, thrombocytes and lymphocyte-like cells. Here, both forms of P. t. tropiduri were analysed using light microscope-based morphological characteristics and phylogenetic inferences based on almost complete mitochondrial genomes of parasites naturally infecting lizards in southeastern Brazil. Although morphologically similar, two distinct phylogenetic lineages infecting erythrocytes and non-erythrocytic cells were found. The lineage found in the erythrocytes forms a monophyletic group with species from Colombia. However, the non-erythrocytic lineage shares a recent common ancestor with Plasmodium leucocytica, which infects leucocytes in lizards from the Caribbean islands. Here, Plasmodium ouropretensis n. sp. is described as a species that infects thrombocytes and lymphocyte-like cells.

Assessment of Associations between Malaria Parasites and Avian Hosts-A Combination of Classic System and Modern Molecular Approach

Simple Summary

Throughout history, frequent outbreaks of diseases in humans have occurred following transmission from animals. While some diseases can jump between birds and mammals, others are stuck to closely related species. Understanding the mechanisms of host–parasite associations will enable us to predict the outbreaks of diseases and will therefore be important to society and ecological health. For decades, scientists have attempted to reveal how host–parasite associations are formed and persist. The key is to assess the ability of the parasite to infect and reproduce within the host without killing the host. Related studies have faced numerous challenges, but technical advances are providing solutions and are gradually broadening our understanding. In this review, I use bird malaria and related blood parasites as a model system and summarize the important advances in techniques and perspectives and how they provide new approaches for understanding the evolution of host–parasite associations to further predict disease outbreaks.

Abstract

Avian malaria and related haemosporidian parasites are responsible for fitness loss and mortality in susceptible bird species. This group of globally distributed parasites has long been used as a classical system for investigating host–parasite associations. The association between a parasite and its hosts can be assessed by the prevalence in the host population and infection intensity in a host individual, which, respectively, reflect the ability of the parasite to infect the host and reproduce within the host. However, the latter has long been poorly investigated due to numerous challenges, such as lack of general molecular markers and limited sensitivity of traditional methods, especially when analysing naturally infected birds. The recent development of genetic databases, together with novel molecular methodologies, has shed light on this long-standing problem. Real-time quantitative PCR has enabled more accurate quantification of avian haemosporidian parasites, and digital droplet PCR further improved experimental sensitivity and repeatability of quantification. In recent decades, parallel studies have been carried out all over the world, providing great opportunities for exploring the adaptation of haemosporidian parasites to different hosts and the variations across time and space, and further investigating the coevolutionary history between parasites and their hosts. I hereby review the most important milestones in diagnosis techniques of avian haemosporidian parasites and illustrate how they provide new insights for understanding host–parasite associations.

First Molecular Detection of Polychromophilus Parasites in Brazilian Bat Species

Blood parasites of the Haemosporida order, such as the Plasmodium spp. responsible for malaria, have become the focus of many studies in evolutionary biology. However, there is a lack of molecular investigation of haemosporidian parasites of wildlife, such as the genus Polychromophilus. Species of this neglected genus exclusively have been described in bats, mainly in Europe, Asia, and Africa, but little is known about its presence and genetic diversity on the American continent. Here, we investigated 406 bats from sites inserted in remnant fragments of the Atlantic Forest and Cerrado biomes and urbanized areas from southern Brazil for the presence of Polychromophilus species by PCR of the mitochondrial cytochrome b encoding gene. A total of 1.2% of bats was positive for Polychromophilus, providing the first molecular information of these parasites in Myotis riparius and Eptesicus diminutus, common vespertilionid bats widely distributed in different Brazilian biomes, and Myotis ruber, an endangered species. A Bayesian analysis was conducted to reconstruct the phylogenetic relationships between Polychromophilus recovered from Brazilian bats and those identified elsewhere. Sequences of Brazilian Polychromophilus lineages were placed with P. murinus and in a clade distinct from P. melanipherus, mainly restricted to bats in the family Vespertilionidae. However, the sequences were split into two minor clades, according to the genus of hosts, indicating that P. murinus and a distinct species may be circulating in Brazil. Morphological observations combined with additional molecular studies are needed to conclude and describe these Polychromophilus species.

Diversity, distribution, and drivers of Polychromophilus infection in Malagasy bats

Background

Numerous studies have been undertaken to advance knowledge of apicomplexan parasites infecting vertebrates, including humans. Of these parasites, the genus Plasmodium has been most extensively studied because of the socio-economic and public health impacts of malaria. In non-human vertebrates, studies on malaria or malaria-like parasite groups have been conducted but information is far from complete. In Madagascar, recent studies on bat blood parasites indicate that three chiropteran families (Miniopteridae, Rhinonycteridae, and Vespertilionidae) are infected by the genus Polychromophilus with pronounced host specificity: Miniopterus spp. (Miniopteridae) harbour Polychromophilus melanipherus and Myotis goudoti (Vespertilionidae) is infected by Polychromophilus murinus. However, most of the individuals analysed in previous studies were sampled on the western and central portions of the island. The aims of this study are (1) to add new information on bat blood parasites in eastern Madagascar, and (2) to highlight biotic and abiotic variables driving prevalence across the island.

Methods

Fieldworks were undertaken from 2014 to 2016 in four sites in the eastern portion of Madagascar to capture bats and collect biological samples. Morphological and molecular techniques were used to identify the presence of haemosporidian parasites. Further, a MaxEnt modelling was undertaken using data from Polychromophilus melanipherus to identify variables influencing the presence of this parasite

Results

In total, 222 individual bats belonging to 17 species and seven families were analysed. Polychromophilus infections were identified in two families: Miniopteridae and Vespertilionidae. Molecular data showed that Polychromophilus spp. parasitizing Malagasy bats form a monophyletic group composed of three distinct clades displaying marked host specificity. In addition to P. melanipherus and P. murinus, hosted by Miniopterus spp. and Myotis goudoti, respectively, a novel Polychromophilus lineage was identified from a single individual of Scotophilus robustus. Based on the present study and the literature, different biotic and abiotic factors are shown to influence Polychromophilus infection in bats, which are correlated based on MaxEnt modelling.

Conclusions

The present study improves current knowledge on Polychromophilus blood parasites infecting Malagasy bats and confirms the existence of a novel Polychromophilus lineage in Scotophilus bats. Additional studies are needed to obtain additional material of this novel lineage to resolve its taxonomic relationship with known members of the genus. Further, the transmission mode of Polychromophilus in bats as well as its potential effect on bat populations should be investigated to complement the results provided by MaxEnt modelling and eventually provide a comprehensive picture of the biology of host-parasite interactions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03696-0.

Vector incrimination and transmission of avian malaria at an aquarium in Japan: mismatch in parasite composition between mosquitoes and penguins

Background

Captive populations of penguins outside of their natural distributions are often maintained in outdoor facilities, such as zoos and aquariums. Consequently, such penguins in captivity are constantly exposed to mosquito vectors and risk of avian malarial infection during their active period from spring to autumn, which can be lethal to these naïve birds. Previous studies have investigated parasite prevalence in mosquitoes or penguins, but simultaneous investigations, which would be crucial to monitor the transmission dynamics and cycle within a facility, have not been done. To identify dominant lineages and trends, multiple-year surveys are recommended.

Methods

Avian malaria parasites (Plasmodium spp.) and related haemosporidia were tested in penguins and mosquitoes at an aquarium in Japan through multiple years from 2011 to 2018. Prevalence and dynamics were confirmed, and molecular analyses targeting the protozoal cytb gene were used to reveal the transmission cycle. Blood meals of mosquitoes were also identified using molecular methods.

Results

Parasite detection in penguins tended to fluctuate within an individual. Two Plasmodium lineages were consistently detected in mosquitoes that had fed on penguins and wild birds observed around the aquarium. Plasmodium lineage CXPIP09 was detected from both mosquitoes and penguins, suggesting active transmission at this facility. However, Plasmodium cathemerium PADOM02 was only detected in mosquitoes, which may be due to host, vector or parasite-related factors, or detection methods and their limits. Additionally, Haemoproteus larae SPMAG12 was detected from penguins, suggesting active transmission via biting midges.

Conclusions

The mismatch in parasite composition between penguins and mosquitoes shows that multiple aspects such as captive birds, wild birds and vector insects should be monitored in order to better understand and control avian malarial infection within ex-situ conservation facilities. Furthermore, morphological analyses would be needed to confirm competency and infection dynamics of avian malaria parasites.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03669-3.

Cytochrome c oxydase I phylogenetic analysis of Haemogregarina parasites (Apicomplexa, Coccidia, Eucoccidiorida, Haemogregarinidae) confirms the presence of three distinct species within the freshwater turtles of Tunisia

Species of Haemogregarina are apicomplexan blood parasites that use vertebrates as intermediate hosts. Due to limited interspecific morphological characters within the genus during the last decade, 18S rRNA gene sequences were widely used for species identification. As coinfection patterns were recently reported from nuclear molecular data for two sympatric freshwater turtles Mauremys leprosa and Emys orbicularis from Tunisia, our objectives were to design COI specific primers to confirm the presence of three distinct species in both host species. Blood samples were collected from 22 turtles, from which DNAs were extracted and used as templates for amplification. Following different rounds of PCR and nested PCR, we designed specific Haemogregarina COI primers that allowed the sequencing of nine distinct haplotypes. Phylogenetic Bayesian analysis revealed the occurrence of three well-differentiated sublineages that clustered together into a single clade. Based on pairwise genetic distances (p-distance), we confirmed the occurrence of three distinct but phylogenetically closely related species coinfecting M. leprosa and E. orbicularis in the same aquatic environments. Our results demonstrate that the use of fast evolving genes within Haemogregarina will help to investigate the parasite diversity within both intermediate vertebrate and definitive invertebrate hosts, and to assess the evolution, historical biogeography and specificity of haemogregarines.

Diagnosis of Plasmodium vivax by Loop-Mediated Isothermal Amplification in Febrile Patient Samples from Loreto, Perú

Plasmodium vivax is co-endemic with Plasmodium falciparum in Peru, and optimum management requires distinguishing these two species in the blood of patients. For the differential identification of P. vivax and other Plasmodium spp., the Loopamp^TM Malaria Pan Detection Kit in combination with the Loopamp Malaria Pv Detection Kit (Eiken Chemical Co. Ltd., Tokyo, Japan) was used to evaluate 559 whole blood samples collected in 2017 from febrile patients with suspected malaria attending different health facilities in the Loreto region. The Loopamp Malaria Pan Detection Kit showed a sensitivity of 87.7% (95% CI: 83.5-91.9) and a specificity of 94.4% (95% CI: 91.9-96.9) and good agreement with PCR (Cohen's kappa 0.8266, 95% CI: 0.7792-0.874). By comparison, the Loopamp Malaria Pv Detection Kit showed a similar sensitivity (84.4%, 95% CI: 79.0-89.7) and specificity (92.4%, 95% CI: 89.7-95.0) and substantial agreement with PCR (Cohen's kappa: 0.7661, 95% CI: 0.7088-0.8234).

Contaminations contaminate common databases

The polymerase chain reaction (PCR) is a very powerful method to detect and identify pathogens. The high sensitivity of the method, however, comes with a cost; any of the millions of artificial DNA copies generated by PCR can serve as a template in a following experiment. If not identified as contaminations, these may result in erroneous conclusions on the occurrence of the pathogen, thereby inflating estimates of host range and geographic distribution. In the present paper, we evaluate whether several published records of avian haemosporidian parasites, in either unusual host species or geographical regions, might stem from PCR contaminations rather than novel biological findings. The detailed descriptions of these cases are shedding light upon the steps in the work process that might lead to PCR contaminations. By increasing the awareness of this problem, it will aid in developing procedures that keep these to a minimum. The examples in the present paper are from haemosporidians of birds, however the problem of contaminations and suggested actions should apply generally to all kinds of PCR‐based identifications, not just of parasites and pathogens.

Cryptosporidium cf. avium in an inland-bearded dragon (Pogona vitticeps) - A case report and review of the literature

Here, we report the first case of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps) from a wildlife sanctuary in Victoria, Australia. Molecular characterisation was conducted by PCR-coupled sequencing of regions in the small subunit of nuclear RNA (SSU), actin and large subunit of nuclear RNA (LSU) genes. The sequences obtained grouped with those of C. ornithophilus and other C. avium genotypes/variants originating from reptiles or birds. We discuss this case in relation to the current state of knowledge of C. avium of birds and reptiles, considering provenance and environment (agricultural, pet industry, wildlife, zoo or wildlife park) as well as clinical context, and pathological changes associated with cryptosporidiosis in these host animals.

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Characterisation of Cryptosporidium cf. avium from an inland bearded dragon (Pogona vitticeps).

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Molecular differentiation of C. cf. avium from other members of the C. avium clade.

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Pathogenicity of C. cf. avium seems higher than other members of this clade.

Geographic and host distribution of haemosporidian parasite lineages from birds of the family Turdidae

Background

Haemosporidians (Apicomplexa, Protista) are obligate heteroxenous parasites of vertebrates and blood-sucking dipteran insects. Avian haemosporidians comprise more than 250 species traditionally classified into four genera, Plasmodium, Haemoproteus, Leucocytozoon, and Fallisia. However, analyses of the mitochondrial CytB gene revealed a vast variety of lineages not yet linked to morphospecies. This study aimed to analyse and discuss the data of haemosporidian lineages isolated from birds of the family Turdidae, to visualise host and geographic distribution using DNA haplotype networks and to suggest directions for taxonomy research on parasite species.

Methods

Haemosporidian CytB sequence data from 350 thrushes were analysed for the present study and complemented with CytB data of avian haemosporidians gathered from Genbank and MalAvi database. Maximum Likelihood trees were calculated to identify clades featuring lineages isolated from Turdidae species. For each clade, DNA haplotype networks were calculated and provided with information on host and geographic distribution.

Results

In species of the Turdidae, this study identified 82 Plasmodium, 37 Haemoproteus, and 119 Leucocytozoon lineages, 68, 28, and 112 of which are mainly found in this host group. Most of these lineages cluster in the clades, which are shown as DNA haplotype networks. The lineages of the Leucocytozoon clades were almost exclusively isolated from thrushes and usually were restricted to one host genus, whereas the Plasmodium and Haemoproteus networks featured multiple lineages also recovered from other passeriform and non-passeriform birds.

Conclusion

This study represents the first attempt to summarise information on the haemosporidian parasite lineages of a whole bird family. The analyses allowed the identification of numerous groups of related lineages, which have not been linked to morphologically defined species yet, and they revealed several cases in which CytB lineages were probably assigned to the wrong morphospecies. These taxonomic issues are addressed by comparing distributional patterns of the CytB lineages with data from the original species descriptions and further literature. The authors also discuss the availability of sequence data and emphasise that MalAvi database should be considered an extremely valuable addition to GenBank, but not a replacement.

First molecular investigation of haemosporidian parasites in Thai bat species

Malaria parasites in the phylum Apicomplexa (Order: Haemosporida) infect diverse vertebrates and invertebrate hosts. At least seven genera of haemosporidian parasites have been described to exclusively infect bats. Most of these parasites remain enigmatic with a poorly known host range. Here, we investigated 271 bats belonging to 21 species and seven families from six provinces of Thailand. Overall, 124 out of 271 bats (45.8%) were positive for haemosporidian parasites, while none had Plasmodium, based on microscopic examination of blood smears and PCR amplification. We obtained 19 distinct cytochrome b (cytb) nucleotide haplotypes of Hepatocystis from seven bat species (families: Craseonycteridae, Hipposideridae, Pteropodidae, and Rhinolophidae). Nycteria was found in four bat species (Craseonycteridae, Emballonuridae, Megadermatidae, and Pteropodidae) and Polychromophilus in two species (Emballonuridae, Vespertilionidae). Phylogenetic analysis inferred from cytb sequences placed Hepatocystis into 2 different clades. Most Hepatocystis infections were found in insectivorous bats and clustered together with a sequence from Hipposideros larvatus in Cambodia (in subclade 1a). A single sequence of Hepatocystis obtained from a frugivorous bat, Cynopterus brachyotis, was placed in the same clade with Hepatocystis from the same bat species previously reported in Malaysia (clade 2). Nycteria in these Thai bats were clearly separated from the African isolates previously reported in bats in the family Rhinolophidae. Polychromophilus murinus from Myotis siligorensis was placed in a distinct clade (clade 2) from Polychromophilus melanipherus isolated from Taphozous melanopogon (clade 1). These results confirmed that at least two distinct species of Polychromophilus are found in Thailand. Collectively, Hepatocystis presented no host specificity. Although Megaderma spasma seemed to be infected by only Nycteria, its respective parasite does not show specificity to only a single bat host. Polychromophilus murinus and P. melanipherus seem to infect a narrower host range or are somehow restricted to bats in the families Vespertilionidae and Emballonuridae, respectively.

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First molecular analysis of haemosporidian parasites in 21 bat species across Thailand.

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Diverse bat species in Thailand are hosts of various haemosporidian parasites.

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High prevalence of haemosporidians in bats (124/271 bats; 45.8%).

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Hepatocystis, Nycteria, and Polychromophilus were discovered in Thai bats.

Molecular and pathological investigations of Plasmodium parasites infecting striped forest whiptail lizards (Kentropyx calcarata) in Brazil

The genus Plasmodium (Plasmodiidae) ranks among the most widespread intracellular protozoan parasites affecting a wide range of mammals, birds, and reptiles. Little information is available about lizard malaria parasites in South America, and the pathological features of the resulting parasitoses remain unknown or poorly understood. To partially fill in these gaps, we conducted blood smear analysis, molecular detection, and phylogenetic and pathological investigations in lizards inhabiting an Atlantic Forest fragment in Paraiba, Brazil. From 104 striped forest whiptails (Kentropyx calcarata) screened for the presence of haemosporidian parasites, 67 (64.4%) were positive. Four of five Amazon lava lizards (Strobilurus torquatus) we collected from this same area were also positive. A total of 27 forest whiptails were infected with a new genetic lineage of Plasmodium kentropyxi and other Plasmodium lineages were also detected. Histopathological analysis in infected forest whiptails revealed systemic intraerythrocytic Plasmodium stages, mainly gametocytes, in the liver, lung, and heart. Also, the liver of infected lizards had mild to moderate levels of Kupffer cell and melanomacrophage hypertrophy/hyperplasia with sinusoid leukocytosis. Overall, our findings suggest that an endemic Plasmodium species causes histological alterations that are not related to major pathological processes in striped forest whiptails.

Haemosporidian parasites of resident and wintering migratory birds in The Bahamas

In temperate regions, some avian haemosporidian parasites have evolved seasonal transmission strategies, with chronic infections relapsing during spring and transmission peaking during the hosts' breeding season. Because lineages with seasonal transmission strategies are unlikely to produce gametocytes in winter, we predicted that (1) resident birds living within wintering areas of Neotropical migrants would unlikely be infected with North American parasite lineages; and (2) if infected, wintering migratory birds would be more likely to harbor Plasmodium spp. rather than Parahaemoproteus spp. or Haemoproteus spp. parasites in their bloodstreams, as only Plasmodium produces life stages, other than gametocytes, that infect red blood cells. To test these predictions, we used molecular detection and microscopy to compare the diversity and prevalence of haemosporidian parasites among year-round residents and wintering migratory birds during February 2016, on three islands of The Bahamas archipelago, i.e., Andros, Grand Bahama, and Great Abaco. Infection prevalence was low and comparable between migratory (15/111) and resident (15/129) individuals, and it did not differ significantly among islands. Out of the 12 lineages detected infecting migratory birds, five were transmitted in North America; four lineages could have been transmitted during breeding, wintering, or migration; and three lineages were likely transmitted in The Bahamas. Resident birds mostly carried lineages endemic to the Caribbean region. All North American-transmitted parasite lineages detected among migratory birds were Plasmodium spp. Our findings suggest that haemosporidian parasites of migrants shift resource allocation seasonally, minimizing the production of gametocytes during winter, with low risk of infection spillover to resident birds.

Hemoglobin E, malaria and natural selection

It is known that there has been positive natural selection for hemoglobin S and C in humans despite negative health effects, due to its role in malaria resistance. However, it is not well understood, if there has been natural selection for hemoglobin E (HbE), which is a common variant in Southeast Asia. Therefore, we reviewed previous studies and discussed the potential role of natural selection in the prevalence of HbE. Our review shows that in vitro studies, evolutionary genetics studies and epidemiologic studies largely support an involvement of natural selection in the evolution of HbE and a protective role of HbE against malaria infection. However, the evidence is inconsistent, provided from different regions, and insufficient to perform an aggregated analysis such as a meta-analysis. In addition, few candidate gene, genome-wide association or epistasis studies, which have been made possible with the use of big data in the post-genomic era, have investigated HbE. The biological pathways linking HbE and malaria infection have not yet been fully elucidated. Therefore, further research is necessary before it can be concluded that there was positive natural selection for HbE due to protection against malaria.

Lay summary: Our review shows that evidence largely supports an involvement of natural selection in the evolution of HbE and a protective role of HbE against malaria. However, the evidence is not consistent. Further research is necessary before it is concluded.

A longitudinal molecular study of the ecology of malaria infections in free-ranging mandrills

Unravelling the determinants of host variation in susceptibility and exposure to parasite infections, infection dynamics and the consequences of parasitism on host health is of paramount interest to understand the evolution of complex host-parasite interactions. In this study, we evaluated the determinants, temporal changes and physiological correlates of Plasmodium infections in a large natural population of mandrills (Mandrillus sphinx). Over six consecutive years, we obtained detailed parasitological and physiological data from 100 male and female mandrills of all ages. The probability of infection by Plasmodium gonderi and P. mandrilli was elevated (ca. 40%) but most infections were chronical and dynamic, with several cases of parasite switching and clearance. Positive co-infections also occurred between both parasites. Individual age and sex influenced the probability of infections with some differences between parasites: while P. mandrilli appeared to infect its hosts rather randomly, P. gonderi particularly infected middle-aged mandrills. Males were also more susceptible to P. gonderi than females and were more likely to be infected by this parasite at the beginning of an infection by the simian immunodeficiency virus. P. gonderi, and to a lesser extent P. mandrilli, influenced mandrills’ physiology: skin temperatures and neutrophil/lymphocyte ratio were both impacted, generally depending on individual age and sex. These results highlight the ecological complexity of Plasmodium infections in nonhuman primates and the efforts that need to be done to decipher the epidemiology of such parasites.

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Longitudinal epidemiological and physiological data on Plasmodium infection obtained from a wild primate population.

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Elevated chronical infections by two species of Plasmodium.

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Contrasted dynamics of infection and physiological effects of P. gonderi and P. mandrilli.

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Elevated parasitaemia (P. gonderi) in male mandrills in primo-infection by the simian immunodeficiency virus.

Detection of malaria with light microscopy and Nested polymerase chain reaction (Nested PCR) methods in peripheral blood expansions and investigation of the genetic diversity of Plasmodium species by 18S rRNA gene in Southeast of Iran

BACKGROUND

Malaria is a public health concern that leads to about a million deaths worldwide every year. Malaria is caused by the genus Plasmodium, which includes P. falciparum, P. vivax, P. malariae, and P. ovale. Molecular phylogeny is essential to better recognition the evolution of the genus Plasmodium genus and detection of the relative degree of Plasmodium species in humans. The aim of this study was to detect malaria with Light Microscopy (LM) and Nested polymerase chain reaction (Nested PCR) methods in peripheral blood expansions and to investigate the genetic diversity of Plasmodium species by 18S rRNA gene in the southeast of Iran.

METHODS

A total of 97 blood smears were collected from patients suspected to malaria in a 6-year period in the southeast of Iran including Hormozgan, Kerman, and Sistan and Baluchestan provinces. Diagnosis of Plasmodium species on blood smears was performed using LM and Nested PCR methods. In addition, 16 Plasmodium-positive samples were chosen for the determination of genetic diversity.

RESULTS

Overall, 97 of 97 (100%) studied cases were positive by LM while 94 of 97 (96.8%) of them were detected as malaria by Nested PCR. Except for seven cases, Nested PCR confirmed the LM results. These samples involved two P. vivax and five P. falciparum in the LM method. Meanwhile, the Nested PCR was detected in all of the cases as a mixed infection with P. vivax and P. falciparum. The results of the phylogenetic analysis revealed two main clades and five different subclades. About 87.5% of the isolates were located in clade I and contained P. vivax. In addition, 12.5% of the studied isolates involved P. falciparum that was in clade II.

CONCLUSION

According to our results, Nested PCR method had higher sensitivity than LM and is suggested as a good approach for malaria detection. Consideration the wide diversity of tested isolates and the importance of vaccine development, which is affected by this diversity, further studies are needed in this regard.

Molecular characterization of six widespread avian haemoproteids, with description of three new Haemoproteus species

Species of Haemoproteus (Haemosporida, Haemoproteidae) are widespread and often prevalent blood parasites of birds all over the word. They are particularly diverse in tropical countries. Due to limited knowledge of life cycles, these pathogens usually have been considered relatively benign and were neglected in veterinary medicine and bird management. However, recent molecular studies provided evidence that Haemoproteus parasites might cause severe diseases if they infect non-adapted (wrong) avian hosts due to marked damage of organs by exo-erythrocytic stages (megalomeronts). Additionally, high Haemoproteus infections are lethal to blood-sucking insects. Molecular markers are essential for reliable detection and species identification both at tissue stages in vertebrates and sporogonic stages in arthropods however, remain insufficiently developed for wildlife haemosporidian parasites. This study combined PCR-based and microscopic approaches and reported cytochrome b gene (cytb) and apicoplast gene (clpc) markers for characterization of six widespread species of haemoproteids parasitizing common birds wintering in tropics and subtropics of the Old World. Three new Haemoproteus species were described using morphological and molecular markers. Molecular characterization of haemoproteids parasitizing falcons was developed. Morphological and phylogenetic characterization of Haemoproteus tinnunculi (cytb lineage hFALSUB01), H. brachiatus (hLK03), H. parabelopolskyi (hSYAT1), H. homogeneae n. sp. (hSYAT16), H. homopicae n. sp. (hGAGLA07) and H. homominutus n. sp. (hCUKI1) was performed and provides clues for infections diagnostics. This study adds three species to the group of morphologically readily distinct Haemoproteus parasites, which differ in few base pairs (< 1%) in their partial cytb sequences, indicating that low genetic difference in such sequences often show between-species divergence and should be carefully applied in taxonomic biodiversity studies of haemosporidian parasites. Bayesian phylogenetic analysis identified the position of detected lineages in regard of other Haemoproteus species, suggesting that all reported parasites belong to subgenus Parahaemoproteus and likely are transmitted by Culicoides biting midges. Importance of clpc gene sequences was specified in haemosporidian parasite taxonomy on species levels.

Disentangling Leucocytozoon parasite diversity in the neotropics: Descriptions of two new species and shortcomings of molecular diagnostics for leucocytozoids

Avian communities from South America harbor an extraordinary diversity of Leucocytozoon species (Haemosporida, Leucocytozoidae). Here, of 890 birds sampled, 10 (1.2%) were infected with Leucocytozoon parasites. Among them, two new species were discovered and described. Leucocytozoon grallariae sp. nov. and Leucocytozoon neotropicalis sp. nov. were found in non-migratory highland passeriforms belonging to the Grallaridae and Cotingidae, respectively. They both possess gametocytes in fusiform host cells. However, due to combining microscopic examination and molecular detection, it was revealed that these parasites were present in co-infections with other Leucocytozoon species, which gametocytes develop in roundish host cells, therefore exhibiting two highly distant parasite lineages isolated from the same samples. Remarkably, the lineages obtained by cloning the mtDNA genomes were not captured by the classic nested PCR, which amplifies a short fragment of cytochrome b gene. Phylogenetic analyses revealed that the lineages obtained by the classic nested PCR clustered with parasites possessing gametocytes in roundish host cells, while the lineages obtained by the mtDNA genome PCR protocol were closely related to Leucocytozoon parasites possessing gametocytes in fusiform host cells. These findings suggest problems with the sensitivity of the molecular protocols commonly used to detect Leucocytozoon species. A detailed analysis of the primers used in the classic nested PCR revealed a match with DNA sequences from those parasites that possess gametocytes in roundish host cells (i.e., Leucocytozoon fringillinarum), while they differ with the orthologous regions in the mtDNA genomes isolated from the samples containing the two new species. Since these are mixed infections, none of the lineages detected in this study can be assigned accurately to the new Leucocytozoon morphospecies that develops in fusiform host cells. However, phylogenetic analyses allowed us to hypothesize their most probable associations. This study highlights the need for developing detection methods to assess the diversity of Leucocytozoon parasites accurately.

Plasmodium Genomics and Genetics: New Insights into Malaria Pathogenesis, Drug Resistance, Epidemiology, and Evolution

Protozoan Plasmodium parasites are the causative agents of malaria, a deadly disease that continues to afflict hundreds of millions of people every year. Infections with malaria parasites can be asymptomatic, with mild or severe symptoms, or fatal, depending on many factors such as parasite virulence and host immune status. Malaria can be treated with various drugs, with artemisinin-based combination therapies (ACTs) being the first-line choice. Recent advances in genetics and genomics of malaria parasites have contributed greatly to our understanding of parasite population dynamics, transmission, drug responses, and pathogenesis. However, knowledge gaps in parasite biology and host-parasite interactions still remain. Parasites resistant to multiple antimalarial drugs have emerged, while advanced clinical trials have shown partial efficacy for one available vaccine. Here we discuss genetic and genomic studies of Plasmodium biology, host-parasite interactions, population structures, mosquito infectivity, antigenic variation, and targets for treatment and immunization. Knowledge from these studies will advance our understanding of malaria pathogenesis, epidemiology, and evolution and will support work to discover and develop new medicines and vaccines.

Population structure of avian malaria parasites

The geographic distribution of genetic diversity in malaria parasite populations (Apicomplexa: Haemosporida) presumably influences local patterns of virulence and the evolution of host-resistance, but little is known about population genetic structure in these parasites. We assess the distribution of genetic diversity in the partial Domain I of apical membrane antigen 1 (AMA1) in three mtDNA-defined lineages of avian Plasmodium to determine spatial population structure and host-parasite genetic relationships. We find that one parasite lineage is genetically differentiated in association with a single host genus and among some locations, but not with respect to other hosts. Two other parasite lineages are undifferentiated with respect to host species but exhibit geographic differentiation that is inconsistent with shared geographic barriers or with isolation-by-distance. Additional differentiation within two other lineages is unassociated with host species or location; in one case, we tentatively interpret this differentiation as the result of mitochondrial introgression from one of the lineages into a second lineage. More sampling of nuclear genetic diversity within populations of avian Plasmodium is needed to rule out coinfection as a possible confounding factor. If coinfections are not responsible for these findings, further assessment is needed to determine the frequency of mitonuclear discordance and its implications for defining parasite lineages based on mitochondrial genetic variation.

OPEN RESEARCH BADGES

This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at Genbank https://www.ncbi.nlm.nih.gov/genbank/, accession numbers MK965548-MK965653 and MK929797-MK930264.

Novel Molecular Synapomorphies Demarcate Different Main Groups/Subgroups of Plasmodium and Piroplasmida Species Clarifying Their Evolutionary Relationships

The class Hematozoa encompasses several clinically important genera, including Plasmodium, whose members cause the major life-threating disease malaria. Hence, a good understanding of the interrelationships of organisms from this class and reliable means for distinguishing them are of much importance. This study reports comprehensive phylogenetic and comparative analyses on protein sequences on the genomes of 28 hematozoa species to understand their interrelationships. In addition to phylogenetic trees based on two large datasets of protein sequences, detailed comparative analyses were carried out on the genomes of hematozoa species to identify novel molecular synapomorphies consisting of conserved signature indels (CSIs) in protein sequences. These studies have identified 79 CSIs that are exclusively present in specific groups of Hematozoa/Plasmodium species, also supported by phylogenetic analysis, providing reliable means for the identification of these species groups and understanding their interrelationships. Of these CSIs, six CSIs are specifically shared by all hematozoa species, two CSIs serve to distinguish members of the order Piroplasmida, five CSIs are uniquely found in all Piroplasmida species except B. microti and two CSIs are specific for the genus Theileria. Additionally, we also describe 23 CSIs that are exclusively present in all genome-sequenced Plasmodium species and two, nine, ten and eight CSIs which are specific for members of the Plasmodium subgenera Haemamoeba, Laverania, Vinckeia and Plasmodium (excluding P. ovale and P. malariae), respectively. Additionally, our work has identified several CSIs that support species relationships which are not evident from phylogenetic analysis. Of these CSIs, one CSI supports the ancestral nature of the avian-Plasmodium species in comparison to the mammalian-infecting groups of Plasmodium species, four CSIs strongly support a specific relationship of species between the subgenera Plasmodium and Vinckeia and three CSIs each that reliably group P. malariae with members of the subgenus Plasmodium and P. ovale within the subgenus Vinckeia, respectively. These results provide a reliable framework for understanding the evolutionary relationships among the Plasmodium/Piroplasmida species. Further, in view of the exclusivity of the described molecular markers for the indicated groups of hematozoa species, particularly large numbers of unique characteristics that are specific for all Plasmodium species, they provide important molecular tools for biochemical/genetic studies and for developing novel diagnostics and therapeutics for these organisms.

Avian haemosporidians in the cattle egret (Bubulcus ibis) from central-western and southern Africa: High diversity and prevalence

We described the geographic distribution of 82 haemosporidian lineages (Plasmodium, Haemoproteus, and Leucocytozoon) in the cattle egret sampled in five countries in central-western and southern Africa. Seventy-three lineages have not previously been reported. We determined the prevalence of three haemosporidians in the samples. We investigated the influence of the internal environment of the host and environmental variables on the Plasmodium diversity and whether environmental variables may explain spatial variations in the prevalence of Plasmodium. We screened DNA from 509 blood samples from nestlings in 15 African colonies for infection by sequencing the cytochrome b gene of parasites. The molecular phylogenetic analysis was performed using Bayesian methods and including sequences from the MalAvi and GeneBank databases. We found 62 new Plasmodium lineages in a clade with MYCAME02, which is a lineage described in waterbirds and recently identified in birds of prey as Plasmodium paranucleophilum. Two Haemoproteus lineages identified in cattle egret formed a distinct group with Haemoproteus catharti and MYCAMH1 (Haemoproteus spp.). Seven Leucocytozoon lineages found in the cattle egret clustered with Leucocytozoon californicus. We found different Plasmodium diversities among the colonies sampled, demonstrating that the internal environment of the host is not the primary determinant of diversity. A linear mixed-effects multivariate model showed that precipitation was positively associated with Plasmodium diversity when controlling for the effects of temperature, colony composition (mixed and non-mixed species) and country. Moreover, a generalized mixed model showed that temperature was positively associated with the prevalence of Plasmodium when controlling for precipitation, elevation and country. We conclude that the cattle egret is a good model for future haemosporidian studies, as we found a significant number of new lineages in this host, which occupies regions with different climate characteristics where environmental variables exert an influence on the diversity and prevalence of Plasmodium.

Culicoides species community composition and infection status with parasites in an urban environment of east central Texas, USA

BACKGROUND

Despite their importance as vectors of zoonotic parasites that can impact human and animal health, Culicoides species distribution across different habitat types is largely unknown. Here we document the community composition of Culicoides found in an urban environment including developed and natural sites in east central Texas, a region of high vector diversity due to subtropical climates, and report their infection status with haemoparasites.

RESULTS

A total of 251 individual Culicoides were collected from May to June 2016 representing ten Culicoides species, dominated by C. neopulicaris followed by C. crepuscularis. We deposited 63 sequences to GenBank among which 25 were the first deposition representative for six Culicoides species: C. arboricola (n = 1); C. nanus (n = 4); C. debilipalpis (n = 2); C. haematopotus (n = 14); C. edeni (n = 3); and C. hinmani (n = 1). We also record for the first time the presence of C. edeni in Texas, a species previously known to occur in the Bahamas, Florida and South Carolina. The urban environments with natural area (sites 2 and 4) had higher species richness than sites more densely populated or in a parking lot (sites 1 and 3) although a rarefaction analysis suggested at least two of these sites were not sampled sufficiently to characterize species richness. We detected a single C. crepuscularis positive for Onchocercidae gen. sp. DNA and another individual of the same species positive for Haemoproteus sacharovi DNA, yielding a 2.08% prevalence (n = 251) for both parasites in this species.

CONCLUSIONS

We extend the knowledge of the Culicoides spp. community in an urban environment of Texas, USA, and contribute to novel sequence data for these species. Additionally, the presence of parasite DNA (Onchocercidae gen. sp. and H. sacharovi) from C. crepuscularis suggests the potential for this species to be a vector of these parasites.

Low occurrence of hemosporidian parasites in the Neotropic cormorant (Phalacrocorax brasilianus) in Chile

Hemosporidian parasites rarely infect aquatic birds. Few studies have been conducted in South America identifying some lineages of the genera Plasmodium, Leucocytozoon, and Haemoproteus, but none has been done in the Neotropic cormorant (Phalacrocorax brasilianus). This species is widely distributed through the American continent, from Southern USA to Tierra del Fuego, using a wide range of aquatic habitats. We molecularly studied the occurrence and diversity of hemosporidian lineages infecting individuals of Neotropic cormorant across a broad latitudinal gradient in Chile (Arica to Tierra del Fuego). As expected, a very low occurrence of individuals infected by Plasmodium sp. (4/123, 3.3%) and Leucocytozoon sp. (2/123, 1.6%) was detected. We found no evidence of Haemoproteus sp. We identified one lineage of Plasmodium (ZEMAC01) and one new lineage of Leucocytozoon (PHABRA01) infecting cormorants. Individuals infected by Plasmodium sp. were birds from only one site (i.e., Chillán), whereas Leucocytozoon sp. was found in one bird from Valdivia and another one from Tierra del Fuego. Our results expand the known range of hemosporidian parasite lineages in aquatic birds providing an essential baseline data that contribute to a better understanding of the geographic range of hemosporidian parasites infecting Phalacrocoracidae in South America.

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.

Combining morphological and molecular data to reconstruct the phylogeny of avian Haemosporida

The traditional classification of avian Haemosporida is based mainly on morphology and life history traits. Recently, molecular hypotheses have challenged the traditional classification, leading to contradictory opinions on whether morphology is phylogenetically informative. However, the morphology has never been used to reconstruct the relationships within the group. We inferred the phylogeny of avian Haemosporida from 133 morphological characters present in blood stages. We included all species with at least one mitochondrial gene characterized (n = 93). The morphological hypothesis was compared with the one retrieved from mitochondrial DNA (mtDNA) nucleotide sequences and a hypothesis that used a combination of morphological and molecular data (i.e., total evidence). In order to recover the evolutionary history and identify phylogenetically and taxonomically informative characters, they were mapped on the total evidence phylogeny. The morphological hypothesis presented more polytomies than the other two, especially within Haemoproteus. In the molecular hypothesis, the two Haemoproteus subgenera are paraphyletic, and some relationships within Parahaemoproteus were resolved. By combining the morphological and molecular data, we were able to resolve the majority of polytomies and posterior probabilities increased. We identified a unique combination of morphological traits, clearly differentiating avian Haemosporida genera, sub-genera of Leucocytozoon and Haemoproteus, and some Plasmodium sub-genera. Plasmodium had the highest number of synapomorphies. Furthermore, 86% of the species presented a unique combination of taxonomically informative characters. A limiting factor was the mismatch of traits characterized in species descriptions, leading to a morphological matrix with a considerable amount of missing data, particularly for the stages of early young and young gametocytes (67% of all missing data). Characters lacking information for the majority of species included the colour of pigment granules, the cytoplasm appearance, and the presence and dimensions of vacuoles. According to our results, the combination of morphology and mtDNA proved to be a robust alternative to reconstruct the relationships among avian Haemosporida, obtaining a resolution and support similar to that obtained using full mitochondrial genome sequences for over 100 lineages.

Sedentary songbirds maintain higher prevalence of haemosporidian parasite infections than migratory conspecifics during seasonal sympatry

Long-distance migrations influence the physiology, behavior, and fitness of migratory animals throughout their annual cycles, and fundamentally alter their interactions with parasites. Several hypotheses relating migratory behavior to the likelihood of parasitism have entered the literature, making conflicting, testable predictions. To assess how migratory behavior of hosts is associated with parasitism, we compared haemosporidian parasite infections between two closely related populations of a common North American sparrow, the dark-eyed junco, that co-occur in shared habitats during the non-breeding season. One population is sedentary and winters and breeds in the Appalachian Mountains. The other population is migratory and is found in seasonal sympatry with the sedentary population from October through April, but then flies (≥ 900 km) northwards to breed. The populations were sampled in the wild on the shared montane habitat at the beginning of winter and again after confining them in a captive common environment until the spring. We found significantly higher prevalence of haemosporidian parasite infections in the sedentary population. Among infected juncos, we found no difference in parasite densities (parasitemias) between the sedentary and migrant populations and no evidence for winter dormancy of the parasites. Our results suggest that long-distance migration may reduce the prevalence of parasite infections at the population level. Our results are inconsistent with the migratory exposure hypothesis, which posits that long-distance migration increases exposure of hosts to diverse parasites, and with the migratory susceptibility hypothesis, which posits that trade-offs between immune function and migration increase host susceptibility to parasites. However, our results are consistent with the migratory culling hypothesis, which posits that heavily infected animals are less likely to survive long-distance migration, and with the migratory escape hypothesis, which posits that long-distance migration allows host populations to seasonally escape areas of high infection risk.

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background

Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load.

Results

We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests.

Conclusions

The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2940-3) contains supplementary material, which is available to authorized users.

Phylogeny of Hepatocystis parasites of Australian flying foxes reveals distinct parasite clade

Hepatocystis parasites are close relatives of mammalian Plasmodium species and infect a range of primates and bats. Here, we present the phylogenetic relationships of Hepatocystis parasites of three Australian flying fox species. Multilocus phylogenetic analysis revealed that Hepatocystis parasites of Pteropus species from Australia and Asia form a distinct clade that is sister to all other Hepatocystis parasites of primates and bats from Africa and Asia. No patterns of host specificity were recovered within the Pteropus-specific parasite clade and the Hepatocystis sequences from all three Australian host species sampled fell into two divergent clades.

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First molecular phylogeny of Hepatocystis parasites in Australian flying foxes.

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Hepatocystis parasites of Pteropus form a distinct clade.

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Lack of host species specificity as distinct hallmark of Hepatocystis parasites.

Keys to the avian malaria parasites

BACKGROUND

Malaria parasites (genus Plasmodium) are widespread in birds. These pathogens cause pathology of blood and various organs, often resulting in severe avian malaria. Numerous recent studies have reported DNA sequences of avian malaria parasites, indicating rich genetic diversity and the possible existence of many undescribed species. However, the majority of reported Plasmodium lineages remain unidentified to species level, and molecular characterization is unavailable for the majority of described Plasmodium parasites. During the past 15 years, numerous new Plasmodium species have been described. However, keys for their identification are unavailable or incomplete. Identification of avian malaria parasites remains a difficult task even for experts, and this precludes development of avian malariology, particularly in wildlife. Here, keys for avian malaria parasites have been developed as a baseline for assisting academic and veterinary medicine researchers in identification of these pathogens. The main obstacles and future research priorities have been defined in the taxonomy of avian Plasmodium species.

METHODS

The data were considered from published articles and type and voucher material, which was accessed in museums in Europe, the USA and Australia. Blood films containing various blood stages of the majority of described species were examined and used for the development of dichotomous keys for avian Plasmodium species.

RESULTS

In all, 164 published articles were included in this review. Blood stages of avian Plasmodium parasites belonging to subgenera Haemamoeba, Giovannolaia, Novyella, Bennettinia and Huffia were analysed and compared. Illustrated keys for identification of subgenera and species of these parasites were developed. Lists of invalid and synonymous Plasmodium parasite names as well as names of doubtful identity were composed.

CONCLUSION

This study shows that 55 described species of avian Plasmodium can be readily identified using morphological features of their blood stages. These were incorporated in the keys. Numerous synonymous names of Plasmodium species and also the names belonging to the category species inquirenda exist, and they can be used as reserves for future taxonomy studies. Molecular markers are unavailable for 58% of described Plasmodium parasites, raising a task for the current avian malaria researchers to fill up this gap.