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.

Cooperative Research

Avian pathogens and vectors, Kahuku Unit of Hawaii Volcanoes National Park — USGS Pacific Island Ecosystems Research Center

Avian Malaria — National Wildlife Health Center

Avian Malaria/Pox — University of Wisconsin Department of Forest and Wildlife Ecology Samuel Research Group

  • Publications

  • Will 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 future bird–mosquito–malaria dynamics in response to alternative climate projections from the Coupled Model Intercomparison Project. 

    Global Change Biology, September 2015

  • Avian 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 important role in the decline and extinction of many native forest birds. However, few studies have attempted to estimate disease transmission and mortality, survival, and individual species impacts in this distinctive ecosystem. 

    Ecosphere, v. 6, issue 6, June 2015

  • Ecology 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.

    U.S. Geological Survey Fact Sheet 2005-3151