A team of researchers at McMaster University has uncovered the existence of malaria 2,000 years ago at the height of the Roman Empire — changing scientist's understanding of how the disease evolved and how widespread the parasite was.

Malaria is believed to have originated in Africa, with the first modern case of the disease found 136 years ago in Constantine, Algeria. But this new genetic research suggests the malaria parasite, Plasmodium falciparum, which is responsible for 450,000 deaths every year, existed centuries before in Italy.

The new analysis has found evidence of malaria in the remains of two adults, dating from the height of the Roman Empire. This discovery has shifted the commonly held belief that malaria was spread more recently by immigrants from Africa.

"What I think is interesting about them is that they're from two different localities suggesting that, you know most people thought, 'oh it must be the port cities if it occurred because it's where you have immigrants coming in and it must be coming from Africa because that's where malaria is endemic today,'" said Hendrik Poinar, lead researcher, evolutionary geneticist and director of McMaster University's Ancient DNA Centre.

"Again it's one of these situations where we blame immigrants on the arrival of infection, but in this case we find it midland in a rural centre, far away from any coastal centres, along a major route, so it certainly would have had access to trade coming from either side of the peninsula.

Evolutionary geneticist Hendrik Poinar of McMaster University's Ancient DNA Centre team of researchers used mitochondrial genomic evidence extracted from teeth to uncover the existence of malaria in Italy 2,000 years ago. (Sheryl Nadler/Canadian Press) "But clearly it was endemic in Italy probably for a long time."

This is the first time scientists have been able to prove the existence of the parasitic disease in imperial Rome, which was only previously illustrated in historical records, documenting reoccurring fevers, Poinar explained.

The team at McMaster University was assisted by scientists at the National Museum of Prehistory and Ethnography in Rome and the University of Sydney. They extracted DNA from the teeth of 58 adults, using a technique called "targeted enrichment" technology to recover the malaria parasite that is centuries old.

"Skeletons that have been sitting in the ground for 2,000 years are a mixture of things that you died with and of course everything that is colonized in the skeleton after that," Poinar said.

"Malaria sits in that mixture at infinitesimally relative amounts... So what you do is you use a molecular fishing bait that can pull out malaria-like fragments specifically."

McMaster University's Ancient DNA Centre has been investigating ancient infectious diseases in skeletal remains, like the black plague, cholera and the plague of Justinian for five years.

"We've been very interested in the infections that have been problematic over time and malaria is just one of those," he said. "We've constantly asked ourselves, do we buy the evidence out there, is it real, is it no good?"

This ancient malaria genome is now helping scientists to better understand the disease, the ancient makeup of the virus is "relatively similar to today's malaria," Poinar stated.

Poinar and his team plan to continue their research, now looking at the nuclear genome found in a cell's nucleus, instead of the mitochondrial genome located in a cell's mitochondria, to better understand what the parasite looked like before the influence of vaccines and modern medicine.

"There's been a lot of anti-malarial drugs that have been used in the last 100 years... has modified [malaria]," he said.

These drugs have changed the disease's genetic make up making the parasite "more susceptible or less susceptible to a particular drug," but this 2,000 year old evidence gives researchers an understanding of the "natural diversity of malaria gives us knowledge of how these types of pathogens can evade drugs and develop resistance to them," explained Poinar.

"Understanding a pathogens evolutionary trajectory and origins in history is critical for its control and eradication."