Preventive Medicine and Zoonoses Flashcards

Bovine tuberculosis (Mycobacterium bovis) is primarily controlled in US cattle herds through which regulatory program?

Answer: Federal-state cooperative test-and-slaughter program

The US bovine TB eradication program relies on the caudal fold tuberculin test (CFT) with slaughter of reactor animals and traceback investigations under federal-state cooperative authority.

Which of the following zoonotic diseases is correctly matched with its primary animal reservoir in the United States?

Answer: Hantavirus pulmonary syndrome — deer mice (Peromyscus maniculatus)

Deer mice (Peromyscus maniculatus) are the primary reservoir for Sin Nombre virus, the agent of hantavirus pulmonary syndrome in the US.

A sensitivity analysis on a diagnostic test reveals that at 85% sensitivity and 95% specificity, the positive predictive value (PPV) drops below 50% when disease prevalence falls below approximately:

Answer: 8%

With 85% sensitivity and 95% specificity, PPV falls below 50% when prevalence drops below approximately 8%, illustrating how low prevalence dramatically reduces PPV.

Marek's disease in poultry is best prevented through which approach?

Answer: Vaccination of day-old chicks in the hatchery combined with management practices

Vaccination of day-old chicks at the hatchery with herpesvirus of turkeys (HVT) or bivalent vaccines is the cornerstone of Marek's disease prevention, as the vaccine prevents tumor formation but not infection.

Which of the following is the recommended approach for managing a confirmed Porcine Epidemic Diarrhea Virus (PEDV) outbreak on a naïve sow farm?

Answer: Controlled feedback of virus-containing material to non-pregnant gilts and sows to accelerate herd immunity

Controlled exposure (feedback) of non-pregnant animals to virus-containing material accelerates development of lactogenic immunity in sows before farrowing, protecting piglets through colostrum.

Psittacosis in humans is caused by Chlamydia psittaci. Which group of workers is at highest occupational risk?

Answer: Pet bird owners, aviary workers, and poultry processing plant employees

Pet bird owners, aviary workers, and poultry processing employees have the highest exposure to C. psittaci through contact with infected birds or inhalation of dried fecal dust.

The 'Swiss cheese model' of accident causation, as applied to veterinary biosecurity, describes:

Answer: Multiple imperfect layers of protection where aligned holes allow pathogen penetration

The Swiss cheese model illustrates that multiple imperfect biosecurity layers are needed because any single layer has gaps (holes), and disease only penetrates when holes in all layers align simultaneously.