Etiological agent = Erysipelothrix rhusiopathiae

Erysipelothrix rhusiopathiae is a small, facultative anaerobic, weakly gram (+) staining rod. It infects and causes disease in a variety of domestic and wild animal species, and is directly zoonotic to people exposed to infected animals.

Erysipelothrix rhusiopathiae infection in animals:

In pigs:

Pigs are the reservoir of most importance for veterinary medicine. Erysipelothrix rhusiopathiae colonizes the pharynx of pigs and is shed in the feces, urine or oronasal secretions of 30-50% of healthy swine. It can also be isolated from feces, soil, water etc. in an infected animal's environment.

Clinical presentations in pigs:

• acute septicemia
  • fever, prostration, anorexia, vomiting, reluctance to walk
  • Hemorrhages may be present in multiple organs throughout the body.
  • Mortality can be quite high.
• "Diamond skin disease"
  • erythematous skin lesions
    • These may be the classic diamond-shaped lesions or more diffuse edema and erythema.
    • The lesions are due to vasculitis and thromboembolism.
• chronic forms of infection include endocarditis and arthritis.

Pigs are routinely vaccinated against Erysipelothrix in the U.S., although as the prevalence decreases, vaccination may also decrease. This may lead to local outbreaks of erysipelas in naive populations.

• In 2001, 190 pigs at a county fair in Iowa had to be shipped to slaughter because of exposure to pigs with erysipelas.

Erysipelas in other animals:

• polyarthritis in lambs and calves (infections occur most often via umbilical or tail docking wounds)
• "bluecomb" septicemia in turkeys and other species of fowl (chickens, chukars, ducks, emus, parrots, peacocks, pheasants)
  • weakness, cyanosis, erythematous/hemorrhagic combs and snood
• septicemia and skin lesions in dolphins
  • Erysipelothrix rhusiopathiae has also been isolated from alligators, crocodiles and fish

Erysipelothrix rhusiopathiae infection in humans:

Infection with Erysipelothrix rhusiopathiae in humans is called "erysipeloid" and dates back to at least 1870.

• The disease that is referred to as "erysipelas" in humans is actually a form of cellulitis caused by infection with Streptococcus.

Human infections occur primarily via direct contact with infected animals and are, thus, occupational diseases for people such as veterinarians, abattoir workers and fisherman. (In the later case, erysipelas is called"fish handler's disease"- the organism is commonly carried subclinically in the mucoid slime covering the scales of fish.)

• Infection occurs via contamination of skin wounds (most commonly on the hands) and leads to a unique, raised, cellulitis lesion that is highly pruritic (intense burning sensation) and characterized by purplish-red discoloration and edema of the skin.
  • A more diffuse cutaneous form can also occur when lesions progress from the initial site to other cutaneous sites on the body. Systemic symptoms (e.g., fever, malaise, muscle aches, headaches) accompany these cutaneous lesions more commonly than when only solitary skin lesions develop at a wound site.
  • Occasionally the infection may also spread to deeper tissues, leading to arthritis in the joints of the fingers, or septicemia/endocarditis.
    • There are two reports of septicemic Erysipelothrix infection in humans who ate undercooked pork.

Treatment and prevention:

• The antibiotic of first choice for treatment of erysipelas in animals and people is penicillin. The organism is also generally susceptible to cephalosporins and clindamycin, and these may be used for treatment in people.
• Caution and hygiene are important to prevent infection when working with potentially infected animals or in potentially contaminated environments.

References:
Acha, P.N. and B. Szyfres (Eds.). 1989. Zoonoses and Communicable Diseases Common to Man and Animals. Pan American Health Organization; Washington, D.C.

Benenson, A.S. (Ed.). 1995. Control of Communicable Diseases Manual. American Public Health Assoc.; Washington, D.C.

Brooke, C.J. and T.V. Riley. 1999. Erysipelothrix rhusiopathiae: bacteriology, epidemiology and clinical manifestations of an occupational pathogen. J. Med. Microbiol. 48:789-799.

Chastel, C. et al. 1975. Une petite epidemie d'erysipeloide apres depecage d'un globicephale. Nouv. Presse Med. 4:1803-05. (French language publication regarding human infection from contact with an infected whale)

Dilbone, R.P. 1965. Erysipelas suspected in two porpoises. J.A.V.M.A. 147:1085.

Reboli, A.C. and W.E. Farrar. 1995. Erysipelothrix rhusiopathiae, in: Principles and Practice of Infectious Diseases (Eds. G.L. Mandel, J.E. Bennett and R. Dolin), pp. 1894-1896. Churchill Livingston, Inc.; New York, NY.

Timoney, J.F., J.H. Gillespie, F.W. Scott and J.E. Barlough. 1988. Hagan and Brunner's Microbiology and Infectious Diseases of Domestic Animals, pp.. Comstock Publishing Assoc.; Ithaca, NY.

Wood, R.L. 1992. Erysipelas, in: Diseases of Swine (Eds. Leman, A.D. et al.) pp. 475-486. Iowa State University Press; Ames, Iowa.