Tuberculosis, Paratuberculosis, Rabies Flashcards by Danica Polbos

This disease manifests as a chronic granulomatous caseous-necrotising inflammatory process that primarily affects the lungs and their draining lymph nodes.

Bovine tuberculosis

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Causative agent of Bovine TB:

Mycobacterium bovis

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Mode of transmission of M. bovis:

Inhalation of aerosols
Ingestion
Breaks in the skin

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Transmission of TB via infective bites is common in these species:

Badgers

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In bovine TB, what is the name given to the structure formed when the purulent to caseous necrotic center of a lesion calcifies and becomes surrounded by granulation tissue and a fibrous capsule?

tubercle

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In case of Bovine TB, the initial granulomatous lesions in the organ and regional lymph node are known as the:

primary complex

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Bovine TB formation of tubercles are usually found in these sites:

Lymph nodes of head and thorax

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The single most important diagnostic test for TB:

Intradermal tuberculin test

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It is responsible for much of the pathology of TB and fundamental to the tuberculin skin test widely used for diagnosis in large animals

delayed-type hypersensitivity

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The main approaches to the control of TB in production animals:

test-and-cull
abbatoir surveillance

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Tuberculosis lesions outside the lung usually results from:

Hematogenous dissemination

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Bovine TB is considered a zoonotic disease. What is the PRIMARY route of transmission to humans in settings where control programs are lacking?

Ingestion of unpasteurized dairy products

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Describe the typical lesion associated with bovine tuberculosis:

A chronic granulomatous caseous-necrotizing process

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Mycobacterium bovis belongs to which bacterial family?

Mycobacteriaceae

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Which of the following is NOT a common route of M. bovis transmission in cattle?

a) Inhalation of aerosols
b) Ingestion of contaminated feed
c) Transplacental transmission
d) Direct contact with infected skin lesions

Direct contact with infected skin lesions

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M. bovis shedding in cattle can occur through various routes. Which of the following is LEAST likely to be a source of shedding?

a) Respiratory secretions
b) Feces
c) Saliva
d) Urine

Saliva

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What is the “primary complex” in the context of TB infection?

The initial granulomatous lesions in the organ and regional lymph node

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Describe the progression of a granuloma in TB:

It may remain stable, progress slowly, or disseminate.

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Which of the following clinical signs is LEAST likely to be associated with bovine TB?

a) Progressive emaciation
b) Acute, high fever
c) Chronic cough
d) Superficial lymph node enlargement

Chronic cough

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What is the MOST characteristic post-mortem finding in bovine TB?

Granulomas (tubercles) in various organs

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The SINGLE most important diagnostic test for TB in animals:

Intradermal tuberculin test

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The tuberculin test relies on which type of hypersensitivity reaction?

Delayed-type hypersensitivity

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What is the active component of the tuberculin skin test?

Purified protein derivatives (PPDs)

What is a disadvantage of the single intradermal tuberculin test (SITT)?

Cross-reactions can occur with other mycobacteria

What are the primary control strategies for TB in production animals?

Test-and-cull and abattoir surveillance

Why are TB vaccines generally NOT used in eradication programs?

They interfere with diagnostic assays

Zoonotic TB lesions often have which characteristic? a) They are primarily pulmonary. b) They are often extrapulmonary. c) They are easily diagnosed with standard laboratory procedures. d) They respond well to short-term antibiotic treatment.

They are often extrapulmonary.

Which of the following best describes the pathogenesis of Mycobacterium avium subsp. paratuberculosis (MAP)? a) Rapid proliferation in the bloodstream followed by systemic infection. b) Inhalation of aerosolized bacteria leading to pulmonary infection. c) Ingestion and uptake by macrophages in the Peyer's patches, leading to chronic granulomatous enteritis. d) Direct invasion of the intestinal epithelium, causing acute inflammation and necrosis.

Ingestion and uptake by macrophages in the Peyer's patches, leading to chronic granulomatous enteritis.

A key characteristic of Johne's disease transmission is: a) High infectivity in adult animals, leading to rapid clinical disease onset. b) Fecal shedding often precedes clinical signs, making subclinical animals significant sources of infection. c) Primary transmission through aerosolized droplets in close contact environments. d) Vertical transmission is rare, with minimal risk to the fetus.

Fecal shedding often precedes clinical signs, making subclinical animals significant sources of infection.

Which stage of Johne's disease is characterized by the presence of detectable MAP in feces but absence of clinical signs?

Stage II: Subclinical shedders

The primary diagnostic method for Johne's disease is:

Polymerase Chain Reaction (PCR)

Which of the following clinical signs is NOT typically associated with Johne's disease in cattle? a) Progressive weight loss b) Intermittent or constant diarrhea c) Tenesmus (straining to defecate) d) Ventral edema ("bottle jaw")

Tenesmus (straining to defecate)

The "gold standard" for definitive diagnosis of Johne's disease is:

Necropsy with culture and histopathology

Why is controlling Johne's disease a significant challenge?

Subclinical carriers can shed the organism for extended periods without showing signs.

What management practice is crucial for preventing Johne's disease transmission in young animals?

Segregating young stock from adult animals and their manure.

The pathogenesis of Johne's disease primarily involves:

Granulomatous inflammation in the intestinal tract, impairing nutrient absorption

In advanced Johne's disease, the diarrhea is typically:

Watery and profuse.

Which of the following statements about Johne's disease in small ruminants (sheep and goats) is most accurate? a) Diarrhea is a consistent clinical sign. b) Weight loss may be the only noticeable sign. c) The disease progresses more rapidly compared to cattle. d) Serological tests are highly reliable for early detection.

Weight loss may be the only noticeable sign.

The presence of "bottle jaw" in Johne's disease is primarily due to:

Protein loss from the damaged intestinal tract.

Which of the following is NOT a recommended control measure for Johne's disease? a) Culling heavily shedding animals. b) Vaccination of all animals in the herd. c) Strict biosecurity protocols for introducing new animals. d) Pasteurization of colostrum and milk.

Vaccination of all animals in the herd.

Which of the following best describes the lesions associated with Johne's disease? a) Ulcerative lesions throughout the gastrointestinal tract. b) Thickening and corrugation of the intestinal wall, particularly in the ileum. c) Abscess formation in the mesenteric lymph nodes. d) Necrosis of the intestinal villi.

Thickening and corrugation of the intestinal wall, particularly in the ileum.

The role of cell-mediated immunity in Johne's disease is:

Important in controlling infection but may not always eliminate it.

The zoonotic potential of MAP is:

Uncertain, with conflicting data regarding its role in Crohn's disease.

Which of the following statements about rabies epidemiology is most accurate? a) Rabies is primarily a disease of domestic animals, with wildlife playing a minor role. b) The global distribution of rabies is uniform, with similar prevalence in all regions. c) The dog is the most important reservoir of rabies worldwide, particularly in Asia and Africa. d) Rabies transmission is exclusively through bites, with no other routes of infection.

The dog is the most important reservoir of rabies worldwide, particularly in Asia and Africa.

The incubation period of rabies is characterized by:

Prolonged and highly variable duration, influenced by exposure site and viral dose.

Which of the following is NOT a typical clinical sign of rabies in cattle? a) Paralysis b) Aggression and excitation c) Increased milk production d) Difficulty swallowing (dysphagia)

Increased milk production

The primary mechanism of rabies virus transmission is:

Bites from infected animals.

Rabies virus exhibits a strong tropism for:

Nervous tissue

Negri bodies, a characteristic feature of rabies infection, are:

Viral inclusion bodies found within the cytoplasm of infected cells

Which diagnostic methods is considered the most reliable for confirming rabies infection?

Direct fluorescent antibody test (dFA) on brain tissue

Post-exposure prophylaxis for rabies in humans typically involves:

Wound cleaning, vaccination, and rabies immune globulin (RIG) administration.

The paralytic form of rabies in cattle is primarily characterized by:

Progressive muscle weakness and paralysis.

Rabies virus travels from the site of entry to the central nervous system via:

Peripheral nerves

The presence of rabies virus in the saliva indicates that:

The animal is capable of transmitting the virus.

In cattle, rabies infection is most often associated with:

Contact with infected wild animals.

The incubation period for rabies is typically longest when the exposure site is:

Distal from the central nervous system.