Avian Malaria
Avian malaria is a mosquito-borne disease of birds caused by a protozoan parasite (Plasmodium relictum). P. relictum reproduces in avian red blood cells. If the parasite load is sufficiently high, the bird loses red blood cells (anemia). Because red blood cells are critical for moving oxygen about the body, loss of these cells can lead to progressive weakness and, eventually, death.
This disease was introduced to Hawaii and native honeycreepers are highly susceptible. Avian malaria has contributed to population declines and extinction of Hawaiian forest birds. USGS scientists are investigating population impacts and how the dynamics of this disease change with elevation and climate change.
Hawaiian forest bird populations have been negatively affected by the non-native avian malaria parasite. In 2015, the USGS was a partner in the development of models to (1) understand avian malaria dynamics in different species and at different elevations and (2) forecast avian malaria risk in light of climate change. Malaria infections are highest at low elevations and over 90 percent of infected scarlet Hawaiian honeycreepers (I’iwi) die from this disease.
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Domesticated Australian and Timor zebra finches (Taeniopygia guttata castanotis, and T. guttata guttata, respectively) were inoculated with canary (Serinus canaria) blood containing a Hawaiian isolate of Plasmodium relictum (lineage GRW04), a hemoparasite that causes avian malaria. In two experimental trials, Timor, but not Australian zebra finches developed parasitemia that was detected by microsAuthorsErik K. Hofmeister, Christopher N. Balakrishnan, Carter T. AtkinsonThe epidemiology of avian pox and interaction with avian malaria in Hawaiian forest birds
Despite the purported role of avian pox (Avipoxvirus spp.) in the decline of endemic Hawaiian birds, few studies have been conducted on the dynamics of this disease, its impact on free‐living avian populations, or its interactions with avian malaria (Plasmodium relictum). We conducted four longitudinal studies of 3–7 yr in length and used generalized linear models to evaluate cross‐sectional prevaAuthorsMichael Samuel, Bethany L. Woodworth, Carter T. Atkinson, Patrick J. Hart, Dennis LapointeCharacterization of Plasmodium relictum, a cosmopolitan agent of avian malaria
BackgroundMicroscopic research has shown that Plasmodium relictum is the most common agent of avian malaria. Recent molecular studies confirmed this conclusion and identified several mtDNA lineages, suggesting the existence of significant intra-species genetic variation or cryptic speciation. Most identified lineages have a broad range of hosts and geographical distribution. Here, a rare new lineaAuthorsGediminas Valkiunas, Mikas Ilgūnas, Dovilė Bukauskaitė, Karin Fragner, Herbert Weissenböck, Carter T. Atkinson, Tatjana IezhovaAssessing the potential of translocating vulnerable forest birds by searching for novel and enduring climatic ranges
Hawaiian forest birds are imperiled, with fewer than half the original >40 species remaining extant. Recent studies document ongoing rapid population decline and pro- ject complete climate-based range losses for the critically endangered Kaua’i endemics ‘akeke’e (Loxops caeruleirostris) and ‘akikiki (Oreomystis bairdi) by end-of-century due to projected warming. Climate change facilitates the upwaAuthorsLucas B. Fortini, Lauren R. Kaiser, Adam E. Vorsino, Eben H. Paxton, James D. JacobiMitigating future avian malaria threats to Hawaiian forest birds from climate change
Avian malaria, transmitted by Culex quinquefasciatus mosquitoes in the Hawaiian Islands, has been a primary contributor to population range limitations, declines, and extinctions for many endemic Hawaiian honeycreepers. Avian malaria is strongly influenced by climate; therefore, predicted future changes are expected to expand transmission into higher elevations and intensify and lengthen existingAuthorsWei Liao, Carter T. Atkinson, Dennis LaPointe, Michael D. SamuelCollapsing avian community on a Hawaiian island
The viability of many species has been jeopardized by numerous negative factors over the centuries, but climate change is predicted to accelerate and increase the pressure of many of these threats, leading to extinctions. The Hawaiian honeycreepers, famous for their spectacular adaptive radiation, are predicted to experience negative responses to climate change, given their susceptibility to introAuthorsEben H. Paxton, Richard J. Camp, P. Marcos Gorresen, Lisa H. Crampton, David L. Leonard, Eric VanderWerfAvian malaria in a boreal resident species: long-term temporal variability, and increased prevalence in birds with avian keratin disorder
The prevalence of vector-borne parasitic diseases is widely influenced by biological and ecological factors. Environmental conditions such as temperature and precipitation can have a marked effect on haemosporidian parasites (Plasmodium spp.) that cause malaria and those that cause other malaria-like diseases in birds. However, there have been few long-term studies monitoring haemosporidian infectAuthorsLaura C. Wilkinson, Colleen M. Handel, Caroline R. Van Hemert, Claire Loiseau, Ravinder N. M. SehgalChanges in the prevalence of avian disease and mosquito vectors at Hakalau Forest National Wildlife Refuge: a 14-year perspective and assessment of future risk
Throughout the main Hawaiian Islands, introduced mosquito-borne disease has had, and continues to have, a profound impact on the distributions and abundance of native Hawaiian forest birds. Populations of remaining native forest birds are largely restricted to high elevation forests where mean temperatures are marginal for vector and parasite development and limited availability of larval mosquitoAuthorsDennis LaPointe, Jacqueline M. Gaudioso-Levita, Carter T. Atkinson, Ariel N. Egan, Kathleen HayesWill a warmer and wetter future cause extinction of native Hawaiian forest birds?
Isolation of the Hawaiian archipelago produced a highly endemic and unique avifauna. Avian malaria (Plasmodium relictum), an introduced mosquito-borne pathogen, is a primary cause of extinctions and declines of these endemic honeycreepers. Our research assesses how global climate change will affect future malaria risk and native bird populations. We used an epidemiological model to evaluate futureAuthorsWei Liao, Oliver Elison Timm, Chunxi Zhang, Carter T. Atkinson, Dennis LaPointe, Michael D. SamuelAvian malaria in Hawaiian forest birds: Infection and population impacts across species and elevations
Wildlife diseases can present significant threats to ecological systems and biological diversity, as well as domestic animal and human health. However, determining the dynamics of wildlife diseases and understanding the impact on host populations is a significant challenge. In Hawai‘i, there is ample circumstantial evidence that introduced avian malaria (Plasmodium relictum) has played an importanAuthorsMichael D. Samuel, Bethany L. Woodworth, Carter T. Atkinson, P. J. Hart, Dennis LaPointeEcology and diagnosis of introduced avian malaria in Hawaiian forest birds
Avian malaria is a disease caused by species of protozoan parasites (Plasmodium) that infect birds. Related species commonly infect reptiles, birds and mammals in tropical and temperate regions of the world. Transmitted by mosquitoes, the parasites spend part of their lives in the red blood cells of birds (Figure 1). Avian malaria is common in continental areas, but is absent from the most isolateAuthorsCarter T. Atkinson - News