Lessons on TB and heart disease from beavers and mummies

Two little history lessons for today.

CT scans of ancient mummies show that heart disease is not a consequence of modern lifestyles. And the 18th century Canadian fur trade may explain why TB is so hard to eliminate.

1. On medical papyri, Egyptian physicians have recorded symptoms of angina, heart attacks, and congestive heart failure in patients thousands of years ago.

Now, researchers have conducted the most detailed study yet of atherosclerosis – plaque accumulation that can lead to heart attacks and strokes – among ancient Egypt's upper classes. They performed whole body CT scans (pictured) on 52 mummies dating between 1981 BC and AD 364.

Gregory Thomas of the University of California at Irvine and colleagues found that, of the 44 mummies still possessing identifiable heart tissue, 45% exhibited hardening of the arteries.

The earliest known case of coronary artery disease was found in the 3,550-year-old mummy of an Egyptian princess, Ahmose-Meyret-Anon.

The Egyptians ate more fruit and vegetables and less meat than we do and their meat was leaner. Though, according to ancient hieroglyphic inscriptions, wealthy ancient Egyptians relished such calorie-rich fare as cakes sweetened with honey, ScienceNOW reports.

But they didn’t smoke tobacco and likely got more exercise than many of us. "So we think there must be other risk factors that we are missing," Thomas says.

“We may understand atherosclerosis less well than we think,” he adds. It may be that humans are predisposed to atherosclerosis, and perhaps its focus should shift to genetics.

The study was published in the Journal of the American College of Cardiology this week.

2. The 18th century Canadian fur trade is still reflected in the genetic signature of tuberculosis bacteria, according to new research tracing the spread of Mycobacterium tuberculosis from European immigrants to Canadian aboriginals.

Along with historical and demographic info, a team led by Caitlin Pepperell of Stanford analyzed M. tb genes from Quebecers of European ancestry alongside bacteria from native populations in Ontario, Saskatchewan, and Alberta.

The most common strain spread through close contact between geographically separate groups and marriages between French fur traders and indigenous women. Small M. tb populations persisted in native communities for about a century, enduring "at a low, grumbling level,” Pepperell says.

TB epidemics later erupted after environmental and social changes, like the extermination of buffalo and confinement to reservations.

The research, according to Pepperell, shows how TB can spread widely yet persist at almost unnoticeable levels (without hacking coughs) until stressful conditions, such as crowding or poor nutrition, weaken human hosts and give the bacteria a leg up.

This may explain why modern TB detection and eradication is so difficult. "We have thrown a lot of resources at TB, but it has really hung on,” Pepperell says.

Today, approximately one-third of the world harbors M. tb. In 2009, TB killed about 1.7 million people globally.

The study was published in the Proceedings of the National Academy of Sciences yesterday.

Top image: Maiherpri undergoes CT scanning / Michael Miyamoto
Bottom image: Mycobacterium tuberculosis / CDC

This post was originally published on Smartplanet.com