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.

Forests of opportunities and mischief: disentangling the interactions between forests, parasites and immune responses

“…Specifically, the infection risk is determined by the relative abundance of vectors; the more vectors present, the higher the infection risk. In addition, vectors are habitat-dependent, mostly on habitats with mild temperatures and a minimum range of humidity, for reproduction (Santiago-Alarcon et al, 2012). Additionally, we suggest that competition for territories will negatively affect adult condition, as well as the development of hatchlings and fledglings, because when infected they have to devote resources to combat parasites.…”

“…Therefore, vector presence and abundance will co-determine the infection risk of vector-borne parasites at any given place (Santiago-Alarcon et al, 2013a, b). The higher the number of parasites transmitted from vector to host, the greater the chance that parasites can actually infect the host -a low parasite dose might be more effectively counteracted by the host's immune defense than a higher one (Santiago-Alarcon et al, 2012).…”

Avian haemosporidian parasites in an urban forest and their relationship to bird size and abundance

“…In Mooswald forest we have investigated Culicoides vectors (Santiago-Alarcon et al 2012a, 2013a, which are implicated in the transmission of Haemoproteus parasites (Valkiūnas 2005;Santiago-Alarcon et al 2012b). We have shown that most species of Culicoides, even those previously considered ornithophilic, are generalists taking blood meals from both mammals and birds (Santiago-Alarcon et al 2012a, 2013a.…”

First record of Aedeomyia squamipennis (Lynch Arribálzaga, 1878) (Diptera: Culicidae) in the state of Maranhão: epidemiological implications and distribution in Brazil

“…Although Ad. squamipennis has never been found infected with avian Plasmodium in Brazil (Santiago-Alarcon et al 2012), this record in Santo Amaro do Maranhão indicates some epidemiological potential. The municipality lies on the Santo Amaro Lake, which borders the western edge of the Lençóis Maranhenses National Park.…”

“…It is known that vector susceptibility to a parasite species can vary among populations, a phenomenon that may be explained by a combination of environmental conditions and ecological factors potentially altering vector-pathogen-host interactions (Santiago-Alarcon et al 2012), in addition to behavioral and ecological variation. Although Ad.…”