Malaria is a potentially fatal disease caused by the Plasmodium parasite which is spread by the bite of an infected Anopheles mosquito. The disease infects 214 million people globally and kills more than 400,000 people yearly.
Scientists have assumed that malaria is a relatively modern disease, being about 8 to 10 million years old. But George Poinar, Jr., a researcher at the College of Science at Oregon State University presents fossil evidence that a form of malaria related to the strain that infects humans, birds and animals existed over 20 million years ago.
More compelling, the research also revealed the presence of a much older, ancestral strain of the malaria parasite present in a 100-million-year-old biting midge preserved in amber. In the study, Poinar suggests that while ancestral forms of the disease used different insect vectors and different malarial strains, they may have helped to shape animal survival and evolution on Earth.
Poinar points out that since the reproductive stage of malaria only occurs in insects, the new study suggests that insects are the primary hosts of the disease and not the vertebrates they infect with the disease-causing protozoa. He goes even further, saying that evidence points toward the Gregarinida, a protozoan parasite group, could have been progenitors of malaria, seeing as they readily infect the insects that are vectors for the disease today.
Poinar and his wife, Roberta were the authors of a 2007 book called, “What Bugged the Dinosaurs? Insects, Disease and Death in the Cretaceous.” In it, they put forth the argument that insects carried diseases that contributed to the widespread extinction of the dinosaurs around the “K-T boundary” about 65 million years ago.
“There were catastrophic events known to have happened around that time, such as asteroid impacts and lava flows,” Poinar said. “But it’s still clear that dinosaurs declined and slowly became extinct over thousands of years, which suggests other issues must also have been at work. Insects, microbial pathogens and vertebrate diseases were just emerging around that same time, including malaria.”
This very interesting study, “What Fossils Reveal About the Protozoa Progenitors, Geographic Provinces, and Early Hosts of Malarial Organisms,” was published in the journal American Entomologist on March 11, 2016.
