Exo-erythrocytic development of Plasmodium matutinum (lineage pLINN1) in a naturally infected roadkill fieldfare Turdus pilaris

First experimental observation on biology of the avian malaria parasite Plasmodium (Novyella) homonucleophilum (lineage pSW2), with remarks on virulence and distribution

Species of subgenus Novyella remain most fragmentarily studied amongst avian malaria agents. Transmission of the recently described Plasmodium (Novyella) homonucleophilum (lineage pSW2) occurs broadly in the Old World, including Europe, however biology of this pathogen remains insufficiently investigated. This study provided the first data on the development of P. homonucleophilum in the experimentally infected Eurasian siskins Spinus spinus exposed by inoculation of infected blood. The parasite strain was isolated from a naturally infected song thrush Turdus philomelos, multiplied in vivo, and inoculated to six Eurasian siskins. The same number of birds were used as negative controls. All exposed birds were susceptible, and the controls remained uninfected during the entire study (172 days). Prepatent period was 8-12 days post exposure (dpe). Maximum parasitaemia reached 50-90 % of infected erythrocytes between 20 and 44 dpe. Then, parasitaemia decreased but remained relatively high during the entire observation. Three of six exposed birds died, indicating high virulence of this infection. The parasitaemia increase coincided with a decline of haematocrit value, indicating anaemia. Polychromasia was evident in all infected birds but not in controls. Body mass of exposed birds increased, coinciding with increased food intake. The latter probably is an adaptation to compensate energy loss of hosts due to the long-lasting parasitism. Exo-erythrocytic stages were not found, suggesting that long-lasting parasitaemia was entirely due to erythrocytic merogony. The lineage pSW2 has been reported broadly in the Old World and is likely a generalist infection. Neglected avian Novyella malaria parasites are worth more attention of researchers due to their cosmopolitan distribution and high virulence.

Unexpected absence of exo-erythrocytic merogony during high gametocytaemia in two species of Haemoproteus (Haemosporida: Haemoproteidae), including description of Haemoproteus angustus n. sp. (lineage hCWT7) and a report of previously unknown residual bodies during in vitro gametogenesis

Neglected avian blood parasites of the genus Haemoproteus (Haemoproteidae) have recently attracted attention due to the application of molecular diagnostic tools, which unravelled remarkable diversity of their exo-erythrocytic (or tissue) stages both regarding morphology and organ tropism levels. The development of haemoproteids might result in pathologies of internal organs, however the exo-erythrocytic development (EED) of most Haemoproteus species remains unknown. Seven individual birds - Curruca communis (1) and Phylloscopus trochilus (6) - with high gametocytaemia (between 1% and 24%) of Haemoproteus angustus n. sp. (hCWT7) and Haemoproteus palloris (lineage hWW1) were sampled in Lithuania, and their internal organs were examined extensively by parallel application of histology and chromogenic in situ hybridization methods. Tissue stages were apparently absent, suggesting that the parasitaemia was not accompanied by detectable tissue merogony. Haemoproteus angustus n. sp. was described and characterized morphologically and molecularly. Sexual process and ookinete development of the new species readily occurred in vitro, and a unique character for Haemoproteus parasites was discovered - the obligatory development of several tiny residual bodies, which were associated with intracellular transformation of both macrogametocytes and microgametocytes before their escape from the host cells and formation of gametes. A DNA haplotype network was constructed with lineages that cluster in one clade with the lineage hCWT7. This clade consists of lineages mostly found in Curruca birds, indicating specificity for birds of this genus. The lineage hCWT7 is mainly a parasite of C. communis. Most reports of this lineage came from Turkey, with only a few records in Europe, mostly in birds wintering in Africa where transmission probably occurs. This study highlights unexpected difficulties in the research of EED even when using sensitive molecular diagnostic tools and extends information about transformation in early stages of gametogenesis in haemosporidian parasites.

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

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

From roads to biobanks: Roadkill animals as a valuable source of genetic data

To protect biodiversity we must understand its structure and composition including the bacteria and microparasites associated with wildlife, which may pose risks to human health. However, acquiring this knowledge often presents challenges, particularly in areas of high biodiversity where there are many undescribed and poorly studied species and funding resources can be limited. A solution to fill this knowledge gap is sampling roadkill (animals that die on roads as a result of collisions with circulating vehicles). These specimens can help characterize local wildlife and their associated parasites with fewer ethical and logistical challenges compared to traditional specimen collection. Here we test this approach by analyzing 817 tissue samples obtained from 590 roadkill vertebrate specimens (Amphibia, Reptilia, Aves and Mammalia) collected in roads within the Tropical Andes of Ecuador. First, we tested if the quantity and quality of recovered DNA varied across roadkill specimens collected at different times since death, exploring if decomposition affected the potential to identify vertebrate species and associated microorganisms. Second, we compared DNA stability across taxa and tissues to identify potential limitations and offer recommendations for future work. Finally, we illustrate how these samples can aid in taxonomic identification and parasite detection. Our study shows that sampling roadkill can help study biodiversity. DNA was recovered and amplified (allowing species identification and parasite detection) from roadkill even 120 hours after death, although risk of degradation increased overtime. DNA was extracted from all vertebrate classes but in smaller quantities and with lower quality from amphibians. We recommend sampling liver if possible as it produced the highest amounts of DNA (muscle produced the lowest). Additional testing of this approach in areas with different environmental and traffic conditions is needed, but our results show that sampling roadkill specimens can help detect and potentially monitor biodiversity and could be a valuable approach to create biobanks and preserve genetic data.

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

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

Prevalence of haemosporidia in Asian Glossy Starling with discovery of misbinding of Haemoproteus-specific primer to Plasmodium genera in Sarawak, Malaysian Borneo

BACKGROUND

Plasmodium, Haemoproteus and Leucocytozoon are three mainly studied blood parasites known to cause malarial and pseudomalarial infections in avian worldwide. Although Sarawak is a biodiversity hotspot, molecular data on blood parasite diversity in birds are absent. The objective of the study is to determine the prevalence of blood parasite in Asian Glossy Starlings (AGS), an urban bird with high population density in Sarawak and to elucidate the phylogenetic relationship with other blood parasite.

METHODS

Twenty-nine carcasses of juvenile AGS that were succumbed to death due to window collision were collected around the vicinity of Universiti Malaysia Sarawak. Nested-multiplex and nested PCR targeting the Cytochrome B gene were used to detect Plasmodium and Haemoproteus, and Leucocytozoon respectively. Two primer sets were used for Haemoproteus detection to increase detection sensitivity, with one being a genus-specific primer.

RESULTS

Fourteen samples (prevalence rate: 48.28%) were found positive for avian Plasmodium. Phylogenetic analysis divided our sequences into five lineages, pFANTAIL01, pCOLL4, pACCBAD01, pALPSIS01 and pALPSIS02, with two lineages being novel. No Haemoproteus and Leucocytozoon was found in this study. However, Haemoproteus-specific primer used amplified our Plasmodium samples, making the primer non-specific to Haemoproteus only.

CONCLUSION

This is the first blood parasite detection study on AGS using carcasses and blood clot as sample source in Sarawak. Due to the scarcity of longer sequences from regions with high genetic plasticity, usage of genus-specific primers should be validated with sequencing to ensure correct prevalence interpretation.