Erysipelas as a disease factor

The infection with Erysipelas rhusiopathiae demonstrates that it is possible to characterize the significance of predisposing factors. The virulence of the agent is most important among the exogenous factors; it determines decisively the course of the disease: 1. paracute course as septicemia; 2. chronic course as polyarthritis; 3. subclinical course nearly without any symptoms. The immune status and the genotype of the host are predominant out of endogenous factors. The importance of immunity is known since a long time. A series of field observations supported the potential genetical influence in the pig. Within the hereditability an association to the MHC (in special genetic lines of rats to the RT 1 system of the MHC) was most recently determined in inbred laboratory animals. Additionally several environmental conditions, which can be summarized as stress, and as endogenous factor the age of the animals are relevant for the pathogenesis of the erysipelas infection. A non variable but most important disposition for special tissues are the so-called "borderline tissues", where accumulation, sedimentation and persistence of bacterial antigens are wellknown as described earlier. This phenomenon is determined by hemodynamic manifestation and quantifiably regulated by cytokines especially interleukin (IL 1) as well as by the tumor necrosis factor (TNF alpha) and prostaglandin PgE2. Additionally the cross reactivity of antibodies of Erysipelas rhusiopathiae against most specific collagen of type II, IX and XI in the pig and in laboratory animals was elaborated. This autoimmune phenomenon called "immunologic mimicry" supports besides the special physiologic conditions as niche of defense a very successful evolutionary adaptation of the agent.