Tuberculosis

• Bovine tuberculosis is a zoonotic disease that primarily affects the respiratory system but it can also spread into the other parts of the body.
• Latent Tuberculosis infection (LTBI) can survive in a nonproliferative stage within the granuloma.
• Tuberculosis (TB) Bovine Tuberculosis Causative Agent Mycobacterium bovis (M. bovis)
• The primary route of transmission for Bovine Tuberculosis is through the exchange of respiratory secretion.
• Nose-to-nose contact, inhalation, consumption/ingestion, and direct contact on wounded skin are other routes of transmission for Bovine Tuberculosis.
• Mycobacterium bovis is under the Family Mycobacteriaceae.
• Pathophysiology of Bovine Tuberculosis involves the inhalation of infected bacilli droplets which are phagocytosed by alveolar macrophage of the host as a defense mechanism to the invading pathogen.
• Granuloma formation in Bovine Tuberculosis consists of dead and degenerated macrophages surrounded by epithelioid cells, granulocytes, and lymphocytes, and multinucleated giant cells.
• Purulent to caseous necrotic center may calcify surrounded by granulation tissue and a fibrous capsule forming the “tubercle” in Bovine Tuberculosis.
• Macrophages are released by B-cells either to terminate or clear the infection or allow the bacteria to proliferate.
• Granuloma formation in Bovine Tuberculosis involves clusters of WBC; a reaction of infection.
• The Comparative Cervical Tuberculin (CCT) test involves incubating a blood sample to stimulate live lymphocytes with tuberculin antigen to produce cytokine interferon gamma, then measuring the amount of interferon gamma by ELISA to classify the animals.
• Lesions in other organs, such as kidneys, adrenal glands, intestines, and reproductive organs, are rare cases of bovine tuberculosis.
• Lymphadenitis, particularly the mediastinal, retropharyngeal, and mesenteric lymph nodes, is a common lesion in bovine tuberculosis.
• Gross lesions of bovine tuberculosis include tuberculous granulomas or nodules in lungs, liver, lymph nodes, and spleen.
• Bovine tuberculosis is difficult to diagnose based on clinical signs alone, and a variety of diagnostic methods are used to confirm its presence.
• Treatment for bovine tuberculosis includes test and cull, quarantine, antibiotic treatment, routine testing, biosecurity measures, quarantine and isolation, and vaccination.
• The Caudal Fold Tuberculin (CFT) test involves injecting a small amount of purified protein derivative (PPD) tuberculin into the fold of the tail.
• Caseous necrosis, a cheesy or granular appearance, is a common lesion in infected tissues.
• Prevention of bovine tuberculosis includes routine testing, biosecurity measures, quarantine and isolation, vaccination, wildlife management, and prevention of spread from infected animals to healthy ones.
• The Comparative Cervical Tuberculin (CCT) test measures cell-mediated immunity in cattle.
• The immune system releases byproducts against the bacteria in Bovine Tuberculosis, consequently, the accumulation of dead WBC, dead tissues, and dead bacteria will accumulate and will result to pus formation.
• Clinical Findings of Bovine Tuberculosis include weakness, loss of condition and appetite, swelling of various lymph nodes, persistent cough and respiratory diseases, emaciation, lethargy, low-grade fever, pneumonia with a chronic, moist cough, and udder involvement (rare).
• Udder involvement in Bovine Tuberculosis is rare, but the disease can result in progressive hardening of the affected quarter and enlargement of the supramammary (top of the udder) lymph nodes.