The enigma of the pathogenesis of the Jarisch-Herxheimer reaction.

The pathophysiological mechanisms of the Jarisch-Herxheimer reaction (JHR) have remained obscure since its original recognition. In light of the many recent advances in various areas of immunobiology it is felt that the JHR merits brief review and re-evaluation of pathogenesis. The JHR was first described in 1895 by Jarisch and in 1902 by Herxheimer and Krause as a transient exacerbation in the appearance of the mucocutaneous lesions of early syphilis after starting treatment with mercury. Subsequently the reaction was described after treatment of the disease with arsenic, bismuth, and more recently with penicillin and immune serum