Deadliest Known Toxin Found—but No Antidote Scientists withholding DNA sequence for now By John Johnson, Newser Staff Posted Oct 15, 2013 4:02 PM CDT Updated Oct 19, 2013 7:28 AM CDT 55 comments Comments File image (Shutterstock) (Newser) – It sounds like a sci-fi thriller plot, except this is very much fact instead of fiction: Scientists in California have found a new strain of botulinum toxin—the deadliest toxin known to man—but they still haven't come up with an antidote, reports New Scientist. As a result, they've taken the unprecedented step of not releasing its DNA sequence to the public in case it gets into the wrong hands. One big reason: an injection of 2 billionths of a gram would kill an adult. Scientists have previously discovered seven families of botulinum, the last in 1970, notes Nature World News. They've got antidotes for the rest, but not for this new one, called type H. “This new toxin, H, cannot be neutralized by any of the currently available antibotulinum antisera, which means that we have no effective treatment for this form of botulism,” the researchers write, according to Yahoo News. They discovered the strain in the feces of a child suffering from botulism. The study is published in the Journal of Infectious Diseases.