[Swine infected with atypical mycobacteria]

Area of Science:

• Veterinary Pathology
• Mycobacteriology
• Immunology

Context:

• Tuberculosis in pigs presents diagnostic challenges.
• Differentiating Mycobacterium avium serotypes is crucial for understanding disease progression.
• Assessing immune responses to various Mycobacterium species in swine is important for disease control.

Purpose:

• To characterize the clinical, immunological, and pathological responses of pigs to spontaneous and experimental mycobacterial infections.
• To identify the specific Mycobacterium species involved in spontaneous porcine tuberculosis.
• To evaluate the diagnostic efficacy of avian and bovine tuberculins in pigs.

Summary:

• Spontaneously tuberculous pigs exhibited robust reactions to avian tuberculin, with Mycobacterium avium (serotypes 2 and 1) isolated from most cases. Lymph node pathology included enlargement, necrosis, and calcification.
• Pigs experimentally infected with other Mycobacterium species (M. intracellulare, M. fortuitum, M. aquae, M. vaccae, M. smegmatis) showed delayed allergic reactions to avian tuberculin and developed proliferative lymph node changes without caseation or calcification.
• Complement fixation tests (CFT) detected genus-specific antibodies in experimentally infected pigs, suggesting a broader immune response.

Impact:

• This study clarifies the etiological agents and pathological features of tuberculosis in pigs, aiding in accurate diagnosis and disease management.
• Findings highlight the importance of avian tuberculin for diagnosing M. avium infections in swine.
• Understanding the differential responses to various mycobacteria informs strategies for controlling tuberculosis in swine populations.