Acute and Chronic Erysipelothrix rhusiopathiae Infection in Lambs

Area of Science:

• Veterinary Pathology
• Bacteriology
• Sheep Diseases

Background:

• Erysipelothrix rhusiopathiae causes polyarthritis in lambs, a common condition with high morbidity.
• This Gram-positive bacterium is a known vertebrate pathogen and commensal.

Purpose of the Study:

• To investigate an outbreak of Erysipelothrix rhusiopathiae infection in a Norwegian Spæl sheep flock.
• To characterize the acute and chronic phases of the disease, including pathological findings and bacterial persistence.

Main Methods:

• Necropsy and bacterial culture from major organs and joints.
• Histopathological examination of affected tissues.
• Real-time polymerase chain reaction (PCR) for bacterial detection.
• Pulsed-field gel electrophoresis (PFGE) for strain typing.

Main Results:

• Acute phase: 20% of lambs showed clinical signs, with E. rhusiopathiae cultured from organs and joints. Lesions included fibrinous polyarthritis and Purkinje cell necrosis.
• Chronic phase: 33% developed chronic polyarthritis with joint lesions. E. rhusiopathiae was cultured from joints, but PCR confirmed persistence in other organs.
• Systemic complications in chronic cases included amyloidosis (spleen, liver), glomerulonephritis, and brain degeneration. Increased ceruloplasmin and haptoglobin levels were observed.

Conclusions:

• Chronic ovine erysipelas is a multisystemic disease extending beyond the joints.
• The same bacterial strain caused both acute and chronic manifestations.
• Further research is needed to understand the full impact and management of this multisystemic infection.