Oldest Malarial Mummies Shed Light on Disease Evolution

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"Tuberculosis is becoming a real problem in developed countries such as the U.S. or Switzerland, where [the bacteria] don't react anymore to antibiotics because they have … mutated," said Frank Rühli, head of the Swiss Mummy Project at the University of Zurich.

Studying ancient diseases that have changed over time could help scientists better understand how modern diseases mutate in reaction to drugs.

"If you go back in the past and see this genetic fingerprint [of a disease], say a hundred years ago or a thousand years ago or ten thousand years ago, it helps you to assess how it might actually react in the future," said Rühli, who was not involved in either study.

This makes mummies and other ancient human remains even more valuable to paleopathology than written records.

"Humans are the best archives of humans," Rühli said. "If you have papyri on which [ancient doctors] diagnosed diseases, it's less reliable than if you actually have molecular or archaeological proof."

Other diagnostic tools, such as radiology and CT scans, have helped researchers find medical abnormalities in mummies, including arthritis, sclerosis, bone fractures, dental problems, and injuries.

(Related: "King Tut Died From Broken Leg, Not Murder, Scientists Conclude" [December 1, 2006].)

But such scans provide little definitive evidence of an infection, and archaeologists frown on more invasive procedures such as autopsies.

Sampling tissues to look at DNA is both less damaging to the mummy and more precise in terms of studying diseases.

"A CT scan of a mummy may identify changes very suggestive of tuberculosis, while DNA analysis provides a clear proof of the infection by showing the specific pathogen," Nerlich, of the German teaching hospital, said.

Path to a Cure?

Although pathologists have not yet used ancient DNA to develop specific treatments for modern diseases, they believe their work has that potential.

Ancient samples of a microorganism's genetic code can show what its DNA looked like before any of its known mutations developed.

An antibiotic designed to target a disease-causing bacteria in its earliest stages could then potentially cure its modern variations.

But getting to that stage requires studying as many samples as possible.

So far scientists have documented dozens of ancient cases of tuberculosis, contributing to the wealth of knowledge about the disease.

"Mycobacteria [such as tuberculosis] has a very strong cell wall, which we think helps to protect the DNA a bit within the mummies," said Albert Zink, head of the Institute for Mummies and the Iceman in Bolzano, Italy.

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