Signs of malaria have been found in the skeleton of a child buried in a Roman cemetery.
British researchers say it is the earliest genetic evidence that the disease plagued the classical civilisations of Rome and Greece. The child was buried at a site north of Rome more than 1,500 years ago.
The DNA evidence provides support for the theory that a lethal outbreak of malaria in AD 5 contributed to the downfall of the Roman Empire.
"We can be fairly sure that the child died of malaria," said Dr Robert Sallares, of the University of Manchester Institute of Science and Technology (Umist), UK, who led the research.
"Ancient DNA research is a new way of investigating the history of disease," he told BBC News Online. "If we can do the same sort of work on material from older sites, we can determine when malaria entered Europe."
Roman fever
Terry Brown, head of the department of Biomolecular Sciences, where the study was carried out, said archaeological and ancient historians had argued for some time about whether malaria was a significant factor in the classical civilisations of Rome and Greece.
"We know that communities in Greece and Rome suddenly died out. There's argument over whether some of these communities were wiped out by malaria," he told BBC News Online.
Genetic analysis had documented cases of malaria in medieval times, said Professor Brown. But the study, due to be published in the journal Ancient Biomolecules, is believed to be the first DNA evidence for malaria as far back in history as late Roman times.
The name malaria is derived from the Italian, (mal-aria) or "bad air". It was also known as Roman fever. It is a very old disease - indeed, prehistoric man is thought to have suffered from malaria.
Each year, 300-500 million people become ill with malaria and several million die, mainly in Africa, India, South East Asia and South America.