Erysipelas - Pig

Description

An infectious disease caused by Erysipelothrix rhusiopathiae. The disease is characterised by sudden death, septicaemia, arthritis, endocarditis, diamond shaped skin lesions, laminitis and abortion in pregnant sows. Carrier pigs act as reservoir of infection and Organisms are excreted in faeces of acutely-affected pig. Infection occurs via ingestion of contaminated food and water, or through skin abrasions.

Signalment

Affects pigs of all ages, most common in pigs kept in poor conditions and in batches of newly bought gilts. May occur in certain conditions often during hot humid weather or in particular buildings or fields.

Diagnosis

Development of the typical diamond shaped lesion on the skin is pathognomic for this disease. Erysipelas should be considered in any cases where fever and lameness occur together, or in farrowing sows who are struggling in combination with a fever. Post-mortem diagnosis may be needed for definitive diagnosis, in particular spleen, kidney, liver, spleen, heart valves,a long bone and synovial tissues should be submitted for bacterial examination. Slender Gram-positive rods can be seen on microscopy of acute lesions; filamentous forms in chronic lesions and on smears. High levels of antibiody may be found in joint fluid and so may aid diagnosis. ELISAs and PCR tests are also avilable which can be used directly on tissue or following culture.

Clinical signs

Clinical outcome depends on susceptibility of pigs and virulence of strain. Pigs are susceptible after maternal antibody waned (after 3 months) and before protective immunity acquired (3 years). Changes in diet, extremes of temperature and fatigue are thought to predispose to infection 3 forms of disease occur:

• Hyperacute
• Acute
• Chronic

Hyperacute: Sudden death, more common in younger pigs. May be found dull, collapsed or pyrexic with a scarlet tinge to the skin.

Acute: Anorexia and pyrexia are the two most common clinical signs of the acute form in young pigs. Affected animals still die but normally afte day in which time they become dyspnoic. Older pigs tend to show pyrexia, anorexia and polydypsia. Pigs show, pink/purple raised areas or extensive diamond-shaped plaques over skin within 24-48 hours of developing clinical signs. If pregnant sows are infcted at this time they may abort.

Chronic: Affected animals can completely recover, Lesions may resolve within a week, or become necrotic and slough. Ear tips may also be lost. The bacteria localises in joints causing of synovial membrane lining + plus hyperaemia and villus formation + lymphocyte and plasma cell infiltration resulting in chronic serofibrinous polyarthritis and also discospondilitis. Initially joints are hot and swollen leading to stiffness, lameness, and non-weight bearing on affected limbs.

• • Joint lesions with erosion of articular cartilage, fibrosis and ankylosis
  • Strong impact on productivity
• Chronic valvular endocarditis:
  • Vegetatic thrombosis of mitral valves
  • Asymptomatic or congestive heart failure and sudden death with stress
• Diagnosis:
  • Diamond-shaped skin lesions
  • No growth on MacConkey agar
  • Colonial characteristics and biochemical tests

Treatment

• • Penicillin and tetracyclines for acute infections
  • Hyperimmune serum
• Control:
  • Hygience
  • Cull chronic cases
  • Isolate affected pigs
  • Live attenuated or inactivated vaccines

• • Most important and most common cause of arthritis
    • • • Also expresses as septicaemic and urticarial lesion on the back (diamond shaped)
    • May involve endocarditis as a sequel
  • Chronic stage
    • More commonly encountered
    • Erosion of articular surface of joints with formation of pannus +/- joint ankylosis
    • Vaccination prevents septicaemic and urticarial forms but has no effect on joints
      • Probably due to dead bacteria still stimulating host immune system
  • Septicaemia lo9calises in meninges and joints
  • Well known in piglets in their first two months of life
  • Expresses as acute fibrinopurulent arthritis