Malaria evolved 100 million years ago

The prehistoric origin of malaria can be traced back to the age of dinosaurs, says a new analysis.

The first vertebrate hosts of this disease were probably reptiles, which at that time would have included the dinosaurs.

Malaria, a scourge on human society that still kills more than 400,000 people a year, is often thought to be of more modern origin, ranging from 15,000 to 8 million years old, caused primarily by one genus of protozoa, Plasmodium, and spread by anopheline mosquitoes.

But the ancestral forms of this disease used different insect vectors and different malarial strains and may literally have helped shape animal survival and evolution on Earth, according to researcher George Poinar.

Poinar suggested that the origins of this deadly disease, which today can infect animals ranging from humans and other mammals to birds and reptiles, may have begun in an insect such as the biting midge more than 100 million years ago.

In previous work, Poinar and his wife, Roberta, implicated malaria and the evolution of blood-sucking insects as disease vectors that could have played a significant role in the extinction of the dinosaurs.

Since the sexual reproduction stage of malaria only occurs in insects, the researcher said that they must be considered the primary hosts of the disease, not the vertebrate animals that they infect with disease-causing protozoa.

Understanding the ancient history of malaria evolution, Poinar said, might offer clues to how its modern-day life cycle works, how it evolved, and what might make possible targets to interrupt its transmission through its most common vector, the Anopheles mosquito.

The study is published in American Entomologist.