It must be a recurrent nightmare for researchers who work with deadly microbes: being killed by your own research subjects. Microbe hunters know better than anyone else just how nasty infectious disease can be, and they spend much of their professional lives wielding bleach and maintaining stringent lab protocols to keep the objects of their fascination at bay. But sometimes one jumps the fence. Just such a tragedy caused the death in 2009 of Malcolm Casadaban
, aged 60, a respected plague researcher at the University of Chicago. But how it did so was a mystery, until now.
Plague has a fearsome reputation, being blamed (unfairly, some believe
) for the medieval Black Death. But the bacteria are far harder to catch than many lab pathogens – in nature you must inhale lots of bacteria, or have them injected by a flea bite. The plague bacteria Casadaban was working with were deliberately weakened, and unlike ordinary plague, they aren’t even on the US list of potential bioweapons bugs
. Medical investigators later found they couldn’t even kill mice with the bacteria that killed the scientist.
So how did Casadaban die? It turns out his death was a medical coincidence
worthy of the hit TV series House
, in which crack diagnosticians try to figure out tough cases. Their patients typically have unusual combinations of conditions, something Casadaban unfortunately fell prey to.
Casadaban’s lab bugs were weak because they have trouble taking up iron, which they need to make crucial enzymes. Unfortunately, unbeknownst to him, Casadaban had haemochromatosis
, a genetic disorder in which people accumulate high levels of iron in their blood and organs. When the weakened bacteria somehow hit Casadaban’s blood, they suddenly received an influx in iron and regained their strength.
There are several tragedies here, besides the loss of a good scientist. One, the bacteria may have entered his bloodstream because, like many experienced researchers, he occasionally didn’t take all the safety precautions, such as rubber gloves. Why bother, with such safe bacteria?
This is one more reminder that nature can bite in ways we don’t always expect. Readers, if you work with microbes – wear the gloves. Worse, Casadaban initially went to the doctor with the classic “flu-like symptoms” typical of nearly every early infection, but sought no further treatment. He then went back three days later as it got worse, and was dead 13 hours after that.
The bacteria were only identified when a hospital doctor learned by chance where the patient worked, and someone tested for plague – five days after he died. Yet plague would have been readily curable with the right antibiotics.
Casadaban never told his doctors he worked in a plague lab. Maybe he feared unleashing the kind of panic experienced by other plague scientists over misplaced fears of bioterrorism. Who knows how many unusual afflictions like this are never diagnosed at all? Surely we can devise the technology to do a better job of diagnosing infections.
Copyright: arcticle: Debora MacKenzie, New Scientist