The toxin from Clostridium botulinum (the bacteria shown here in a coloured scanning electron micrograph) is considered the most deadly in nature: a single gram could kill more than one million people.
DR GARY GAUGLER/SCIENCE PHOTO LIBRARY
Scientists have discovered a new strain — the first in 40 years — ofClostridium botulinum, the bacterium that is ultimately responsible for causing botulism. And although they have reported their findings in a scientific journal, the investigators have taken the extraordinary step of withholding key details of the discovery. That’s because the toxins made by C. botulinum are the most dangerous known to humankind and currently there is no antidote for a toxin generated by the new strain. The fear is that malevolent organizations or rogue governments might use the information to reverse engineer their own version of the new bug, making it a potent and real bioterrorism threat.
A consensus statement on C. botulinum toxin as a biological weapon published in 2001 inJAMA: The Journal of the American Medical Association calculated that “a single gram of crystalline toxin, evenly dispersed and inhaled, would kill more than one million people.”C. botulinum toxin is high on the list of feared biological weapons because minute quantities can fatally paralyze people who swallow or breathe it. It is known or suspected to have been part of bioweapon programs in countries such as the Soviet Union, Iran, Iraq, North Korea and Syria, and was used, fortunately ineptly, in Tokyo in the early 1990s by the Japanese cult Aum Shinrikyo before they turned to the nerve agent sarin.
Until now there have been seven known strains of the bacterium; the toxins they make are labelled A through G. There are antidotes for those, but each antitoxin neutralizes only the specific toxin against which it is made, and none works against the new toxin that has been dubbed H.