Lecture Notes on Swine Erysipelas in Animals

Lecture notes on Swine Erysipelas

1. Lecture Notes on Swine Erysipelas Dr Vidya Singh Senior Scientist Division of Pathology, ICAR-Indian Veterinary Research Institute Izatnagar, Bareilly, UP, India- 243122

2. Swine Erysipelas Synonym : Diamond Skin disease An infectious zoonotic bacterial disease of pigs , caused by Erysipelothrix rhusiopathiae and is characterized by multifaceted clinical presentation - acute septicemia, endocarditis, cutaneous vascular lesions, chronic arthritis, abortion, infertility, reduced growth, and death Economic importance : Loss due to reduced growth and production, death and carcass condemnation Zoonotic potential : Causes erysipeloid in humans —a localized skin infection . Etiology Caused by Erysipelothrix rhusiopathiae , selender , rod/ filamentus , Gram positive non-sporing, non-motile facutative anaerobe , visulaised by Loeffler’s methylene blue or Ziehl-Neelsen , grows at 5-42 o C Resistant to environmental stress ; survives in soil, feces, water, and carcasses for weeks Virulence Factor Neuraminidase – Vascular damage and thrombosis Hyaluronidase Capsular polysaccharide – Anti-phagocytic Surface protective antigens ( SpaA , SpaB ) – Induce immune response

3. Epidemiology and Transmission Geographic distribution : Worldwide Age group : Most commonly affects growing pigs (3 months to 1 year) Reservoirs Tonsils and lymphoid tissues of healthy carrier pigs (20–50%) Rodents, birds, fish may serve as mechanical vectors Transmission Direct : Oral, cutaneous, or via mucous membranes from carrier pigs Indirect : Contaminated bedding, feed, water, or environment Predisposing Factors Abrasions in the skin Immunosuppression Poor hygiene and overcrowding Sudden dietary changes Stress (weaning, transportation)

4. Pathogenesis Entry : via skin abrasions, oral mucosa, or tonsils Multiplication : Bacteria evade phagocytosis due to capsule Bacteremia : Rapid multiplication and dissemination through bloodstream Neuraminidase-mediated endothelial damage → vasculitis , thrombosis Cutaneous infarction → diamond-shaped skin lesions Localization in joints → chronic proliferative polyarthritis Heart valve colonization → vegetative endocarditis Persistent infection may result in chronic carrier state

5. Clinical Signs A. Peracute Form Common in unvaccinated, stressed pigs Sudden death without premonitory signs Often no visible gross lesions at necropsy B. Acute Form High fever (40.5–42°C) Lethargy, anorexia Diamond-shaped erythematous skin lesions over ears, neck, and belly Cyanosis of extremities (ears, tail, scrotum) Stiff gait, reluctant to move Abortion in pregnant sows C. Subacute Form Less severe, milder fever and transient skin lesions May recover or progress to chronic disease D. Chronic Form Develops from untreated or inadequately treated acute cases 1 . Chronic Arthritis Progressive joint swelling , especially in hocks, stifles Lameness , pain, reduced feed intake , " dog sitting" posture Decreased productivity and growth 2 . Vegetative Endocarditis Common on mitral and aortic valves Murmurs , arrhythmias Death due to cardiac insufficiency

6. Gross Pathology Skin Raised, firm, red/purple diamond-shaped lesions ; sloughing in severe cases Joints Thickened joint capsules, yellowish turbid synovial fluid Heart valves Warty vegetations on mitral/aortic valves ; valve thickening Spleen Enlarged, congested, pulpy Lymph nodes Enlarged, edematous Liver Congested, with multifocal necrosis Histopathology Skin Dermal thrombosis, hemorrhage, necrosis ; vascular congestion Joint capsule Synovial cell hyperplasia, mononuclear infiltrate, fibrin exudate Heart Endocarditis with fibrin , bacterial colonies, and inflammatory cells Spleen Lymphoid hyperplasia , congestion Liver Focal necrosis , neutrophilic infiltrate

7. Diagnosis A. Clinical Diagnosis Sudden deaths, diamond-shaped lesions, fever, arthritis in growing pigs B. Laboratory Diagnosis: Gram stain : Thin, filamentous Gram-positive rods in tissues Culture : Blood , tissues on blood agar: small, smooth colonies, weak α-hemolysis PCR : Highly specific and sensitive ELISA : Useful for herd surveillance Histopathology : Vasculitis, thrombosis, vegetative lesions Response to penicillin: Therapeutic response often confirms diagnosis Treatment Penicillin G - 20,000–40,000 IU/kg IM, effective in acute cases Amoxicillin - Broad spectrum; used in-feed or parenterally Erythromycin , Tylosin - For chronic arthritis cases NSAIDs - Control fever and inflammation Water electrolytes - Supportive therapy for dehydration, toxemia Chronic lesions (arthritis, endocarditis) often do not respond well to treatment

8. Control & Prevention A. Vaccination Killed bacterins or live attenuated vaccines Initial dose at 8–12 weeks of age; booster at 6-month intervals Sows: Vaccinate during gestation (~2–4 weeks before farrowing) B. Management Practices All-in/all-out system Regular cleaning, disinfection Avoid overcrowding Minimize stress . Biosecurity Quarantine of new stock Rodent control Avoid mechanical vectors (e.g., contaminated equipment) ZOONOTIC SIGNIFICANCE Human ( Butchers, farmers, veterinarians ) Erysipeloid – localized cutaneous infection with r ed , raised lesions on fingers, pain, swelling . Systemic infection is rare and may involve arthritis or endocarditis