Roy A. Earlé

Bio: Roy A. Earlé is an academic researcher. The author has contributed to research in topics: Leucocytozoon & Haemoproteus. The author has an hindex of 9, co-authored 15 publications receiving 264 citations.

A host-parasite catalogue of the haematozoa of the sub-Saharan birds.

Abstract: The prevalence of avian haematozoa in 826 species of birds representing 73 families of sub-Saharan birds as recorded in the literature or in the files of the International Reference Centre for Avian Haematozoa and the Veterinary Research Institute is presented. The most commonly occurring blood parasites were members of the genus Haemoproteus which were represented by 63 species which occurred in 19.1% of the sample. Twenty-five species of Leucocytozoon were recorded in 8.3% of the birds and represented the second most frequently encountered group of haematozoa. Species of Plasmodium, Trypanosoma, and filarioids (as microfilariae) occurred in 3.5%, 2.5% and 2.8% respectively of the birds sampled; species of Aegyptianella, Atoxoplasma, Babesia and Hepatozoon were infrequently seen. An annotated list of the birds examined for haematozoa is presented and brief descriptions of the species of Haemoproteus and Leucocytozoon in birds of the sub-Saharan zone are included.

An annotated checklist of the valid avian species of Haemoproteus, Leucocytozoon (Apicomplexa: Haemosporida) and Hepatozoon (Apicomplexa: Haemogregarinidae)

Abstract: The valid avian species of the apicomplexan blood parasite genera Haemoproteus, Hepatozoon and Leucocytozoon are arranged according to host family, assuming host familial specificity; salient points of the parasite morphology are recorded where appropriate.

Trypanosomes of some sub-Saharan birds.

Abstract: BENNETT, G.F., EARLE, R.A. & SQUIRES-PARSONS, DEBORAH 1994. Trypanosomas of some sub-Saharan birds. Onderstepoort Journal of Veterinary Research, 61:263- 271 Linear measurements and derived indices from striated trypanosomas in nine species of sub-Saharan birds representing seven families of the Passeriformes, were compared. The dimensions of the striated trypomastigotes from the Carduelinae, Estrildidae, Nectarinidae, Passeridae, Pycnonotidae, Turdinae and Zosteropidae were similar to each other as well as to those of the striated trypanosomes from the boreal owl (Strigidae). All these trypanosomes were considered to be Trypanosoma avium Danilewsky, 1885. A further 20 avian species were considered to harbour T. avium, thus greatly extending the reported host range of this trypanosome. Non-striated trypanosomes from the estrildid Uraeginthus angolensis closely resembled Trypanosoma bouffardi Leger & Blanchard, 1911 in appearance and dimensions, and were considered to be of this species. Additional host records for T. bouffardi from an additional nine avian species have been reported. The uniquely small and stumpy Trypanosoma everetti Molyneux, 1973 was reported from an additional 18 avian species. A large non-striated trypanosome from the laughing dove, Streptopelia senegalensis, was identified as Trypanosoma hannae Pittaluga, 1905 and this species was re-described. An infection of this parasite was also found in a single Streptopelia capicola and a single Streptopelia semitorquata. Two trypanosomes seen in the francolin, Francolinus natalensis, were identified as Trypanosoma calmettei Mathis & Leger, 1909.

New species of avian Hepatozoon (Apicomplexa: Haemogregarinidae) and a re-description of Hepatozoon neophrontis (Todd & Wohlbach, 1912) Wenyon, 1926

Abstract: Seven new species of avian Hepatozoon, H. lanis, H. malacotinus, H. numidis, H. pittae, H. estrildus, H. sylvae and H. zosteropis, respectively, are described from the Laniinae, Malaconotinae, Numidinae, Pittidae, Poephilinae, Sylviinae and Zosteropidae. Hepatozoon adiei Hoare, 1924 is synonymised with Hepatozoon neophrontis (Todd & Wolbach, 1912) Wenyon, 1926 from the Accipitridae and H. neophrontis re-described. Four species of Hepatozoon described by de Beaurepaire Aragao from Brazil are reviewed and Hepatozoon tanagrae (de Beaurepaire Aragao, 1911) Hoare, 1924 is synonymised with H. rhamphocoeli (de Beaurepaire Aragao, 1911) Hoare 1924 and H. brachyspizae (de Beaurepaire Aragao) Hoare, 1924 with H. paroariae (de Beaurepaire Aragao, 1911) Hoare, 1924. Illustrations and measurements for Hepatozoon albatrossi Peirce & Prince, 1980, H. atticorae (de Beaurepaire Aragao, 1911) Hoare, 1924 and H. parus Bennett & Peirce, 1989 are also presented to complete the review of the known avian species. The value of some potential morphological characteristics for distinguishing species of Hepatozoon is discussed.

The Leucocytozoidae of South African birds: Passeriformes.

Abstract: BENNETT, G. F., EARL( R. A. & PEIRCE, M.A., 1992. The Leucocytozoidae of South African birds: Passeriformes. Onderstepoort Journal of Veterinary Research, 59, 235--247 (1992) The leucocytozoids of ten families of Passeriformes-Estrildidae, Fringillidae, Laniidae, Nectarinii­ dae, Passeridae, Ploceidae, Promeropidae, Pycnonotidae, Sturnidae and Zosteropidae-are reviewed. Leucocytozoon roubaudi from the Estrildidae, L. fringillinarum from the Fringillidae, L. balmorali from the Laniidae, L. gentilifrom the Passeridae, L. bouffardifrom the Ploceidae, L. brimontifrom the Pycno­ notidae and L. zosteropis from the Zosteropidae are re-described. Leucocytozoon dutoiti, L. nectari­ niae, L. deswardti, L. pycnonoti and L. sturm are new species described from the Fringillidae (Cardueli­ nae), Nectariniidae, Promeropidae, Pycnonotidae and Sturnidae respectively while L. monardi is con­ sidered to be a synonym of L. gentili and L. molpastis is considered to be a synonym of L. brimonti.

Diversification and host switching in avian malaria parasites

Abstract: The switching of parasitic organisms to novel hosts, in which they may cause the emergence of new diseases, is of great concern to human health and the management of wild and domesticated populations of animals. We used a phylogenetic approach to develop a better statistical assessment of host switching in a large sample of vector-borne malaria parasites of birds (Plasmodium and Haemoproteus) over their history of parasite-host relations. Even with sparse sampling, the number of parasite lineages was almost equal to the number of avian hosts. We found that strongly supported sister lineages of parasites, averaging 1.2% sequence divergence, exhibited highly significant host and geographical fidelity. Event-based matching of host and parasite phylogenetic trees revealed significant cospeciation. However, the accumulated effects of host switching and long distance dispersal cause these signals to disappear before 4% sequence divergence is achieved. Mitochondrial DNA nucleotide substitution appears to occur about three times faster in hosts than in parasites, contrary to findings on other parasite-host systems. Using this mutual calibration, the phylogenies of the parasites and their hosts appear to be similar in age, suggesting that avian malaria parasites diversified along with their modern avian hosts. Although host switching has been a prominent feature over the evolutionary history of avian malaria parasites, it is infrequent and unpredictable on time scales germane to public health and wildlife management.

Evolutionary Relationships, Cospeciation, and Host Switching in Avian Malaria Parasites

Abstract: We used phylogenetic analyses of cytochrome b sequences of malaria parasites and their avian hosts to assess the coevolutionary relationships between host and parasite lineages. Many lineages of avian malaria parasites have broad host distributions, which tend to obscure cospeciation events. The hosts of a single parasite or of closely related parasites were nonetheless most frequently recovered from members of the same host taxonomic family, more so than expected by chance. However, global assessments of the relationship between parasite and host phylogenetic trees, using Component and ParaFit, failed to detect significant cospeciation. The event-based approach employed by TreeFitter revealed significant cospeciation and duplication with certain cost assignments for these events, but host switching was consistently more prominent in matching the parasite tree to the host tree. The absence of a global cospeciation signal despite conservative host distribution most likely reflects relatively frequent acquisition of new hosts by individual parasite lineages. Understanding these processes will require a more refined species concept for malaria parasites and more extensive sampling of parasite distributions across hosts. If parasites can disperse between allopatric host populations through alternative hosts, cospeciation may not have a strong influence on the architecture of host-parasite relationships. Rather, parasite speciation may happen more often in conjunction with the acquisition of new hosts followed by divergent selection between host lineages in sympatry. Detailed studies of the phylogeographic distributions of hosts and parasites are needed to characterize these events.

Diptera vectors of avian Haemosporidian parasites: untangling parasite life cycles and their taxonomy

Abstract: Haemosporida is a large group of vector-borne intracellular parasites that infect amphibians, reptiles, birds, and mammals. This group includes the different malaria parasites (Plasmodium spp.) that infect humans around the world. Our knowledge on the full life cycle of these parasites is most complete for those parasites that infect humans and, to some extent, birds. However, our current knowledge on haemosporidian life cycles is characterized by a paucity of information concerning the vector species responsible for their transmission among vertebrates. Moreover, our taxonomic and systematic knowledge of haemosporidians is far from complete, in particular because of insufficient sampling in wild vertebrates and in tropical regions. Detailed experimental studies to identify avian haemosporidian vectors are uncommon, with only a few published during the last 25 years. As such, little knowledge has accumulated on haemosporidian life cycles during the last three decades, hindering progress in ecology, evolution, and systematic studies of these avian parasites. Nonetheless, recently developed molecular tools have facilitated advances in haemosporidian research. DNA can now be extracted from vectors' blood meals and the vertebrate host identified; if the blood meal is infected by haemosporidians, the parasite's genetic lineage can also be identified. While this molecular tool should help to identify putative vector species, detailed experimental studies on vector competence are still needed. Furthermore, molecular tools have helped to refine our knowledge on Haemosporida taxonomy and systematics. Herein we review studies conducted on Diptera vectors transmitting avian haemosporidians from the late 1800s to the present. We also review work on Haemosporida taxonomy and systematics since the first application of molecular techniques and provide recommendations and suggest future research directions. Because human encroachment on natural environments brings human populations into contact with novel parasite sources, we stress that the best way to avoid emergent and reemergent diseases is through a program encompassing ecological restoration, environmental education, and enhanced understanding of the value of ecosystem services.

Do global patterns of habitat use and migration strategies co-evolve with relative investments in immunocompetence due to spatial variation in parasite pressure?

Abstract: On the basis of associations between the characteristics of breeding and wintering habitats, apparent immunocompetence, and chick energetics of shorebirds (Charadrii), trade-offs between investments in immunofunctioning on the one hand and growth and sustained exercise on the other are suggested, that determine the year-round use of particular types of habitat by long-distance migrating shorebirds. Some species appear restricted to parasite-poor habitats (high arctic tundra, exposed seashores) where small investments in immunomachinery may suffice and even allow for high growth rates. However, such habitats are few and far between, necessitate long and demanding migratory flights in the course of an annual cycle and are often energetically costly to live in. Species evolutionarily opting for parasite-poor habitats may be rather susceptible to parasites and pathogens as a result of investments in sustained exercise (including thermoregulation) rather than immunocompetence. Components of this general hypothesis are perfectly testable, and such tests may shed new light on several other biogeographical, energetic and evolutionary riddles.