Description
An infectious disease caused by Erysipelothrix rhusiopathiae. Affects mainly growing pigs causing septicaemia, [[Joints Inflammatory - Pathology#Arthritis|arthritis] and laminitis.
- Carrier pigs act as reservoir of infection
- Organisms excreted in faeces of acutely-affected pigs
- Ingestion of contaminated food and water, or via skin abrasions
- Clinical outcome depends on susceptibility of pigs and virulence of strain
- Pigs susceptible after maternal antibody waned (after 3 months) and before protective immunity acquired (3 years)
- Change in diet, extremes of temperature and fatigue thought to predispose to infection
- Septicaemic form:
- Acute; incubation period 2-3 days
- Pigs found dead, febrile, depressed, recumbent or with stilted gait
- Mortality high
- Pregant sows abort
- Cutaneous form:
- Diamond skin lesions
- Fewer systemic signs, mortality rates lower
- Pigs febrile with small, pink/purple raised areas or extensive diamond-shaped plaques over skin
- Lesions may resolve within a week, or become necrotic and slough
- Arthritis:
- Older pigs, chronic
- Stiffness, lameness, 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
- Haematology and post mortem, especially liver, spleen, heart valves, synovial tissues
- Slender Gram-positive rods on microscopy of acute lesions; filamentous forms in chronic lesions and smears
- 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
- Causes chronic serofibrinous polyarthritis
- Also causes discospondylitis
- Similar to discospondylitis in dogs
- Thickening of synovial membrane lining + plus hyperaemia and villus formation + lymphocyte and plasma cell infiltration
- Acute stage
- Increased joint fluid + hot swollen joints
- 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