DVM Preventive Medicine and Zoonoses 5 — Questions and Answers
Question 1: A case-control study investigating risk factors for Johne's disease (paratuberculosis) in dairy herds would be most appropriate for which epidemiological scenario?
- A common disease with rapid onset being studied prospectively
- A rare disease or one with a long incubation period where cohort studies are impractical (Correct answer)
- Estimating the absolute risk of disease in an exposed population
- Confirming causality between a pathogen and disease in a new outbreak
Correct answer: A rare disease or one with a long incubation period where cohort studies are impractical
Case-control studies are ideal for rare diseases or those with long incubation periods like Johne's disease, as they work backwards from disease status to identify risk factors efficiently.
Question 2: Which vaccine type is CONTRAINDICATED in immunocompromised animals and pregnant animals due to risk of disease induction?
- Killed (inactivated) vaccines
- Modified live vaccines (MLV) (Correct answer)
- Subunit vaccines
- Toxoid vaccines
Correct answer: Modified live vaccines (MLV)
Modified live vaccines contain attenuated but replication-competent organisms that can revert to virulence or cause disease in immunocompromised or pregnant animals.
Question 3: Monkeypox (Mpox) spillover events in the US have been linked to which animal source?
- Imported non-human primates exclusively
- Prairie dogs exposed to imported African rodents (Gambian pouched rats) (Correct answer)
- Wild raccoons in the southeastern US
- Domesticated rabbits from commercial farms
Correct answer: Prairie dogs exposed to imported African rodents (Gambian pouched rats)
The 2003 US mpox outbreak was linked to prairie dogs that had been housed near imported Gambian pouched rats and other African rodents at an exotic pet distributor.
Question 4: In risk-based surveillance design, which sampling strategy is most efficient for detecting a disease when its prevalence may be clustered in certain subpopulations?
- Simple random sampling across all animals equally
- Stratified or targeted sampling focused on high-risk groups (Correct answer)
- Convenience sampling based on animal accessibility
- Census sampling of every animal on every farm
Correct answer: Stratified or targeted sampling focused on high-risk groups
Stratified or targeted sampling concentrates surveillance effort on high-risk subpopulations, improving efficiency and probability of detection when disease is not uniformly distributed.
Question 5: A dog bite wound from a bat found in a bedroom warrants immediate consideration of rabies post-exposure prophylaxis (PEP) for the human involved primarily because:
- Bats are the most common source of rabies exposure in the US and their bites may not be perceived (Correct answer)
- Bat saliva contains more virus than other rabies vector species
- Bats are always symptomatic when rabid and easily identified
- Bat rabies variants are universally fatal within 24 hours of exposure
Correct answer: Bats are the most common source of rabies exposure in the US and their bites may not be perceived
Bats account for the majority of human rabies deaths in the US because their bites are small and may not be recognized, and because certain situations (sleeping person, bat in room) suggest possible undetected exposure.
Question 6: Which of the following correctly describes the role of the National Animal Health Reporting System (NAHRS) in US veterinary preventive medicine?
- It mandates treatment protocols for all reportable diseases
- It collects and reports state-level data on animal diseases to the OIE/WOAH to maintain US trade status (Correct answer)
- It sets vaccination schedules for all food animal species
- It regulates the approval process for veterinary biologics
Correct answer: It collects and reports state-level data on animal diseases to the OIE/WOAH to maintain US trade status
NAHRS is a voluntary cooperative program that collects state-level animal disease data and reports to the World Organisation for Animal Health (WOAH/OIE), supporting US market access and trade.
Question 7: Antimicrobial stewardship in veterinary medicine requires that extra-label drug use (ELDU) in food animals must NEVER include which class of antimicrobials?
- Macrolides used in cattle
- Fluoroquinolones in food-producing animals (except as labeled) (Correct answer)
- Tetracyclines in poultry feed
- Penicillins in swine
Correct answer: Fluoroquinolones in food-producing animals (except as labeled)
Extra-label use of fluoroquinolones and glycopeptides in food-producing animals is explicitly prohibited by FDA due to concerns about resistance development in critically important human antibiotics.
DVM Preventive Medicine and Zoonoses 5
A case-control study investigating risk factors for Johne's disease (paratuberculosis) in dairy herds would be most appropriate for which epidemiological scenario?