Did malaria help kill off the dinosaurs?
The discovery of an infected mosquito show the origins of the disease are much earlier than previously thought. Bill Condie reports.
Malaria, previously thought to have been a relatively modern disease, may have plagued the dinosaurs, a new study suggests.
The origins of this deadly disease, which kills more than 400,000 people a year, may be in the biting midge more than 100 million years ago, George Poinar, a researcher in the College of Science at Oregon State University, says.
"Scientists have argued and disagreed for a long time about how malaria evolved and how old it is," Poinar says.
"I think the fossil evidence shows that modern malaria vectored by mosquitoes is at least 20 million years old, and earlier forms of the disease, carried by biting midges, are at least 100 million years old and probably much older."
Most previous estimates of the origins of malaria range from 15,000 to eight million years and assume the disease, caused primarily by one genus of protozoa, Plasmodium, was spread then, as now, by anopheline mosquitoes.
But Poinar first discovered a type of malaria in a 15-20 million-year-old fossil in the Dominican Republic, the first fossil record of Plasmodium malaria. He then found numerous oocysts of the malarial parasite Paleohaemoproteusburmacis, in a 100-million-year-old midge, below, the oldest ancestral strain of malaria ever discovered.
The first human recording of malaria is much more recent – in China in 2700 BCE. In 2015 there were 214 million cases worldwide, according to the World Health Organisation. Immunity does not occur naturally and no vaccine has yet been developed.