Tuberculosis

Question 1

Structure

Answer 1

aerobic, non-spore-forming, non-motile, rod-shaped bacteria, gram-positive but lipids in cell wall make uptake of stain difficult

Question 2

Most Important species

Answer 2

M. avium, M. bovis, and M. tuberculosis

Question 3

Reservoirs

Answer 3

M. avium: domestic avian species, passerines, and waterfowl, marsupials
M. bovis: domestic cattle, antelope, camelids, equids, white-tailed deer, bidson, nonhuman primates, carnivores like European badger and ferrets, and marsupials
M. Tuberculosis: mostly humans, nonhuman primates, elephants, and psittacine birds

Question 4

Transmission methods

Answer 4

Inhalation of droplets or ingestion of contaminated food or water (M. bovis)
Ingestion of contaminated food or water via fecal-oral, or of sick carcass (M. avium)
Inhalation of respiratory droplets (M. tuberculosis)

Question 5

Pathogenesis

Answer 5

Phagocytosed by alveolar macrophages-> clear its or let them proliferate-> granuloma formation with dead and degenerate macrophages surrounded by epithelioid cells, granulocytes, lymphocytes, and multinucleated giant cells-> abscessed centers calcify-> obtain fibrous capsule
Ingestion-> primary in pharynx or mesenteric lymph nodes-> nodules in pleura, peritoneum, liver, kidney, spleen, skeleton, mammary glands, reproductive tract, and CNS
Vascular spread can be rapidly fatal, but otherwise chronic slow process

Question 6

Clinical Signs

Answer 6

progressive emaciation, lethargy, weakness, anorexia, diarrhea, fluctuating fever, chronic, intermittent, moist cough, dyspnea, tachypnea, lymph node enlargement

Question 7

Pathologic lesions

Answer 7

-granulomatous nodules throughout lungs, liver, spleen, and lymph nodes
-Liquefactive necrosis or caverns at sites of infection

Question 8

Diagnosis

Answer 8

Postmortem evaluation, intradermal tuberculin test, culture, PCR

Question 9

Treatment

Answer 9

Rarely done unless pet or endangered species, chronic treatment of several types of antibiotics usually 6-9 months

Question 10

Management

Answer 10

-Reportable disease
-most often animal is culled
-limit exposure of domestic animals to wildlife
-proper hygienic measures (deep cleaning) areas of possible wildlife exposure
-national tuberculosis eradication program
-Evaluation of carcasses for TB