In a case study in the Journal of the American Academy of Dermatology, Craft describes six cocaine users recently plagued by the dark purple patches of dying flesh. And while they happened to hail from the country's coastlines, the problem is national.
But drug cartels in South America increasingly prefer to use levamisole, a veterinary antibiotic normally used to deworm cattle, sheep, and pigs. It's not clear why dealers don't just use baking soda all the time, although studies in rats suggest that levamisole might tingle brain receptors in the same way cocaine does. If that's the case, adding it to the supply might be a way to enhance the effects of cocaine on the cheap.