The beautiful birds of Hawai'i have been battling with an invasive malaria parasite known as Plasmodium relictum, and several - perhaps 10 or more - species have been lost to extinction, due, in part to this novel pathogen. In the early 1800's, the mosquito, Culex quinquefasciatus was brought to Hawai'i, and this vector allowed the parasite to take hold on the islands as well. Because the mosquito does not go much above 4000 meters in elevation, many native lowland species have pushed their ranges up in altitude, but since most of the islands are lower than 5,000 meters, there's just not very far to go. P. relictum has an incredibly wide geographic range and infects a large number of bird species, making it an unusual generalist amongst its kin.
The image is from the USGS Microbiology Image Gallery and was taken by Carter Atkinson.