18 months ago, Malcolm Casadaban, a University of Chicago professor of genetics and cell biology, was working on research regarding the Plague. Yeah, that Plague. But the Plague bacteria he was testing was genetically modified, specifically weakened so that it couldn't infect humans. And yet, with sadness, Casadaban somehow got infected and died just a few hours after being rushed to the hospital.
The question that's been boggling scientists thereafter was, well, how in the hell did he die from a pretty much castrated version of the Plague? Until Casadaban, no one has ever died from that weakened version of the Plague, heck, no one has even gotten sick from it since 1959. So what happened?
What became Casadaban's undoing was that he had his own genetic modification, hemochromatosis, that left his body more susceptible to the weakened, lab-testable Plague. Which is unfortunate because that same genetic modification once helped many survivors fight off the Bubonic Plague. He was strong enough for the hard hitting version yet exposed enough to succumb to a weaker strain.
An autopsy found the researcher had a medical condition called hemochromatosis, which causes an excessive buildup of iron in the body, according to the CDC report. The disorder affects about 1 in 400 people and goes unnoticed in about half of patients.
Casadaban's illness is important because of the way the plague bacterium had been weakened. Yersinia pestis needs iron to survive. Normally it gets this iron by stealing it from a host's body with proteins that bind to it and help break it down. To make the bacterium harmless, scientists genetically stripped it of the proteins needed to consume iron.
"It's like having a lion, where we took out all its teeth and all its claws," Alexander said. "But in the case of Dr. Casadaban, the lion didn't even need to have teeth. There was so much iron that it was freely available and easy to get."