Erysipelothrix rhusiopathiae.

Erysipelothrix rhusiopathiae is a facultative, non-spore-forming, non-acid-fast, small, Gram-positive bacillus. The organism was first established as a human pathogen late in the nineteenth century. Three forms of human disease have been recognised since then. These include a localised cutaneous lesion form, erysipeloid, a generalised cutaneous form and a septicaemic form often associated with endocarditis. The organism is ubiquitous and able to persist for a long period of time in the environment, including marine locations. It is a pathogen or a commensal in a wide variety of wild and domestic animals, birds and fish. Swine erysipelas caused by E. rhusiopathiae is the disease of greatest prevalence and economic importance. Diseases in other animals include erysipelas of farmed turkeys, chickens, ducks and emus, and polyarthritis in sheep and lambs. Infection due to E. rhusiopathiae in humans is occupationally related, principally occurring as a result of contact with contaminated animals, their products or wastes, or soil. Erysipeloid is the most common form of infections in humans. While it has been suggested that the incidence of human infection could be declining due to technological advances in animal industries, infection still occurs in specific environments. Additionally, infection by the organism is possibly under-diagnosed due to the resemblance it bears to other infections, and problems encountered in isolation and identification. Various virulence factors have been suggested as being involved in the pathogenicity of E. rhusiopathiae. The presence of a hyaluronidase and neuraminidase has been recognised, and it was shown that neuraminidase plays a significant role in bacterial attachment and subsequent invasion into host cells. The role of hyaluronidase in the disease process is controversial. The presence of a heat labile capsule has been reported as important in virulence. Control of animal disease by sound husbandry, herd management, good sanitation and immunization procedures is recommended.