Also known as Magnan's sign and Magnan-Saury's sign. All three terms refer to a * tactile hallucination consisting of a crawling foreign body beneath or upon the skin that is associated with the chronic use of cocaine. Except for their exclusive association with the use of cocaine, the notions of cocaine bugs, Mag-nan's sign and Magnan-Saury's sign are phe-nomenologically compatible with the notions of * formication, * formicative hallucination, and *insect hallucination. Cocaine bugs tend to be accompanied by pruritus and scratching, which may entail even more pruritis, and hence an aggravation of the tactile hallucinations. They may also be accompanied by delusional parasito-sis, a condition historically referred to as Ekbom's syndrome, after the Swedish neurologist Karl Axel Ekbom (1907-1977), who published various accounts on dermatozoic delusions around 1938. Although the term cocaine bug refers to a type of hallucination confining itself to the tactile modality, the hallucinated bugs involved may also be seen (typically on the skin, within wounds, in the air, on clothing, and on objects in the direct environment). Such accompanying *visual hallucinations may occasionally develop further into hallucinations depicting individuals (i.e. * personifications), animals (i.e. *zoopsia), or objects. An early description of cocaine bugs comes from the Austrian physician Ernst von Fleischl-Marxow (1846-1891), a friend of Sigmund Freud's (1856-1939). Von Fleischl-Marxow experienced the characteristic tactile and visual hallucinations himself, after the prolonged use of morphine, cocaine, and other substances in the context of analgesia from painful neuromata. Ironically, it was Freud who advised him to try cocaine. Formicative hallucinations similar to cocaine bugs, but occurring in the context of amphetamine use, are known as * crank bugs. Incidentally, the slogan "Cocaine each day keeps the bugs away" (sometimes cited with reference to the work of the American neurobiologists James A. Nathanson et al.) does not refer to a method to prevent cocaine bugs, but to the experimental use of cocaine in low concentrations as a natural insecticide in agriculture.
References
Jones, E. (1953). The life and work of Sigmund Freud. Volume 1. The formative years and the great discoveries 1856-1900.New York,NY: Basic Books.
Nathanson, J.A., Hunnicutt, E.J., Kantham, L., Scavone, C. (1993). Cocaine as a naturally occurring insecticide. Proceedings ofthe National Academy of Sciences of the United States ofAmerica, 90, 9645-9648.
Siegel, R.K. (1978). Cocaine hallucinations. American Journal of Psychiatry, 135, 309-314.