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A new test that can identify whether long-dead ancient humans had suffered from malaria could help scientists trace how the disease has evolved.

Archaeologists at Yale University in New Haven, Connecticut, have developed a way of diagnosing the disease in skeletons thousands of years old.

Scientists have used the technique to reveal that infants and toddlers found in a cemetery within an ancient Roman villa in Italy had died of the disease.

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The scientists scraped bone marrow from bone sample to search for telltale crystals of a molecule called hemozoin that show the person who the bone belonged to had been infected with the malaria parasite

The method could now be used to track the spread of malaria back to its first appearance in humans by examining other ancient skeletons for signs of the infection.

Jamie Inwood, an archaeologist at Yale University who led the research team, said: 'The data set we build with this will be revolutionary for establishing the epidemiological curve for malaria in ancient societies.

'By understanding how this parasite reacted to societal shifts in the past, we can aid in predicting its future behavior. We can understand the way it has evolved.'

Miss Inwood and her colleagues developed the test by identifying specific chemical signals and molecules that are found in the bones of people infected with malaria.

They found that a large molecule called hemozoin, which is expelled as a waste product by the malaria Plasmodium parasite.

Using X-ray defraction, Miss Inwood and her team found they were able to identify black crystalline lumps of the molecule in the bone marrow of bone samples.

They tested the technique on the remains of 100 children buried in a cemetery within the ruins of Roman villa at Lugnano in Teverina, Italy.

The bodies, which dated from 550AD, had been buried with heavy roof tiles to weigh them down.

Miss Inwood said: 'Researchers from the University of Arizona had found burial practices that were throwbacks to pagan rituals.

'It was suspected there must have been an epidemic in the community that caused fever or fits.'

With the help of Dr David Soren, an archaeologist at the University of Arizona, Miss Inwood was able to identify hemozoin in femur and humerus bone samples from the site - confirming they had been infected with malaria. 

Malaria is spread by blood sucking female mosquitoes like the Anopheles stephensi mosquito shown above

This electron micrograph shows a malarial sporozoite migrating through the cytoplasm of a mosquito cell

They were able to confirm that the test was accurate using a technique that searches for DNA of the pathogen. However, DNA extraction is not always possible and sometimes unreliable.

Malaria is one of the world's biggest infectious killers, infecting around 200 million people every year and claiming the lives of more than 500,000.

Not all Plasmodium parasites cause malaria in humans. One, known as Plasmodium falciparum, is responsible for most of the deaths while others like Plasmodium malariae cause a milder form of the disease. 

Plasmodium knowlesi rarely cause malaria in humans while other strains of the parasite only infect primates, other mammals or birds. 

The malaria parasite has a life cycle (above) that requires female mosquitoes to pass it between human hosts

Plasmodium falciparum is known to have been in existence for up to 100,000 years, but the population size did not increase until around 10,000 years ago.

It is thought that the disease may have originally evolved in gorillas and then passed to humans, but the evidence for this is inconclusive. 

Professor Roderick McIntosh, an anthropologist at Yale University who also took part in the work, said the test could now help reveal when and where the disease first began infecting humans.

He said: 'There is a constant evolution of this disease, because of changes in human populations and changes in the medicines we use to treat it.

'Knowing the history of the mechanisms by which malaria evolves is a very good thing. We want to put together enough data for a timeline of malaria in humans.'

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