How does avian malaria affect susceptible bird populations?

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Malaria life cycle — malaria Life cycle of a malaria parasite.

Avian malaria, caused by Plasmodium protozoans and transmitted by mosquitoes, significantly impacts susceptible bird populations, particularly perching birds like songbirds.1

The pathology of the disease involves the parasite invading red blood cells and causing them to burst. In susceptible birds, this triggers an acute phase characterized by severe anemia, weakness, depression, and loss of appetite, with mortality rates ranging from 50 to 90 percent. Some birds may become comatose and die, while others develop chronic infections that can lead to organ enlargement and long-term health deterioration.1

The impact is most devastating in populations with little prior exposure. For instance, it contributed to the extinction of about one-third of Hawaiian honeycreepers. Outbreaks in captive settings, such as among penguins, also result in high mortality due to the birds' lack of immunity and the stress of captivity. Conservation efforts currently focus on mosquito control and supporting the natural evolution of genetic resistance in affected species.1