Free DVM Doctor of Veterinary Medicine Preventive Medicine and Zoonoses Questions and Answers — Questions and Answers
Question 1: A client brings a fecal sample from their new 8-week-old puppy. On fecal flotation, you identify eggs of *Toxocara canis*. The client has young children and is concerned about health risks. Which of the following represents the most significant zoonotic risk associated with this parasite in children?
- Cutaneous larva migrans, causing intensely pruritic, serpiginous tracks in the skin.
- Neurocysticercosis, leading to seizures and neurological deficits from larval cysts in the brain.
- Ocular larva migrans, potentially causing unilateral vision loss or strabismus. (Correct answer)
- Hydatid disease, characterized by the formation of large, fluid-filled cysts in the liver and lungs.
Correct answer: Ocular larva migrans, potentially causing unilateral vision loss or strabismus.
Toxocara canis larvae, if ingested by humans (a paratenic host), can migrate through tissues. Migration to the eye causes Ocular Larva Migrans (OLM), a significant cause of unilateral vision loss in children. Cutaneous larva migrans is caused by hookworms (*Ancylostoma spp.*). Neurocysticercosis is caused by the tapeworm *Taenia solium*. Hydatid disease is caused by the tapeworm *Echinococcus granulosus*.
Question 2: You are presented with a 4-year-old raccoon that was found acting aggressively in a suburban neighborhood and has now progressed to showing signs of ataxia and hypersalivation. The animal bites one of your technicians during the initial examination. What is the most critical and immediate first step a veterinarian should take in this situation?
- Administer post-exposure prophylaxis to the technician and the raccoon.
- Immediately begin a 10-day quarantine period for the raccoon to observe for progression of signs.
- Euthanize the raccoon and submit the head for rabies testing, and contact public health authorities. (Correct answer)
- Draw blood from the raccoon for a rabies antibody titer to confirm the diagnosis.
Correct answer: Euthanize the raccoon and submit the head for rabies testing, and contact public health authorities.
Due to the high-risk species (raccoon), classic clinical signs, and human exposure, rabies is the top differential. Public health and safety are paramount. The standard protocol for a suspect rabid wild animal that has exposed a human is to humanely euthanize it and submit the appropriate tissues (brain) for immediate testing to guide human post-exposure prophylaxis decisions. Contacting public health authorities is a legal requirement. A 10-day quarantine is reserved for domestic dogs, cats, and ferrets.
Question 3: A commercial poultry producer is designing a new broiler chicken facility and asks for your input on measures to reduce the introduction and spread of *Salmonella enterica*, a major food safety concern. Which of the following biosecurity measures is most critical for preventing the introduction of *Salmonella* into the flock?
- Implementing a robust vaccination program against Marek's disease.
- Optimizing the lighting program to reduce stress in the flock.
- Sourcing chicks from a certified Salmonella-free hatchery and enforcing strict traffic control for personnel and equipment. (Correct answer)
- Using in-feed antibiotics for growth promotion throughout the grow-out period.
Correct answer: Sourcing chicks from a certified Salmonella-free hatchery and enforcing strict traffic control for personnel and equipment.
The primary entry points for Salmonella into a flock are vertical transmission from the hatchery or horizontal transmission from a contaminated environment. Therefore, starting with Salmonella-free chicks and implementing strict biosecurity protocols, including controlling the movement of people, vehicles, and equipment (traffic control), are the most fundamental and effective preventive measures. While other factors like vaccination for other diseases and stress reduction are important for general flock health, they do not directly prevent the introduction of Salmonella as effectively.
Question 4: A dog from Connecticut presents with shifting leg lameness, fever, and lethargy. A point-of-care ELISA test is positive for antibodies to *Borrelia burgdorferi*. This zoonotic disease, Lyme disease, is transmitted by a specific vector. Which of the following is the primary vector for Lyme disease in the northeastern United States?
- Dermacentor variabilis (American dog tick)
- Amblyomma americanum (Lone star tick)
- Ctenocephalides felis (Cat flea)
- Ixodes scapularis (Black-legged or deer tick) (Correct answer)
Correct answer: Ixodes scapularis (Black-legged or deer tick)
*Borrelia burgdorferi*, the causative agent of Lyme disease, is primarily transmitted by the black-legged tick, *Ixodes scapularis*, in the northeastern and midwestern United States. *Dermacentor variabilis* transmits Rocky Mountain spotted fever, and *Amblyomma americanum* is associated with ehrlichiosis and alpha-gal syndrome. Fleas are vectors for other diseases like plague and bartonellosis but not Lyme disease.
Question 5: Which of the following zoonotic diseases is most commonly transmitted to humans through direct contact with an infected animal's skin lesions or via fomites contaminated with fungal elements?
- Leptospirosis
- Dermatophytosis (Ringworm) (Correct answer)
- West Nile Virus
- Brucellosis
Correct answer: Dermatophytosis (Ringworm)
Dermatophytosis, or ringworm, is a superficial fungal infection of the keratinized tissues (skin, hair, nails). It is classically transmitted by direct contact with the fungal lesions on an infected animal or person, or indirectly through contact with contaminated fomites like bedding or grooming tools. Leptospirosis is typically transmitted via contaminated urine/water, West Nile Virus is vector-borne (mosquitoes), and Brucellosis is transmitted via contact with reproductive tissues or unpasteurized dairy.
Question 6: Which statement best describes the 'One Health' concept as a core principle of modern preventive medicine?
- A focus on developing universal vaccines that are effective for both humans and animals.
- The practice of veterinarians and human physicians collaborating on complex surgical cases.
- An approach that primarily manages zoonotic disease outbreaks by focusing on wildlife reservoir eradication.
- A collaborative, multisectoral approach recognizing that the health of people, animals, and their shared environment are inextricably linked. (Correct answer)
Correct answer: A collaborative, multisectoral approach recognizing that the health of people, animals, and their shared environment are inextricably linked.
The One Health concept is a unifying approach that acknowledges the deep interconnection between human health, animal health (both domestic and wild), and environmental health. It promotes collaboration across multiple disciplines—including veterinary medicine, human medicine, and environmental science—to achieve optimal health outcomes for all. The other options describe much narrower or incorrect applications of this broad, integrated principle.
Free DVM Doctor of Veterinary Medicine Preventive Medicine and Zoonoses Questions and Answers
A client brings a fecal sample from their new 8-week-old puppy.
On fecal flotation, you identify eggs of *Toxocara canis*.
The client has young children and is concerned about health risks.
Which of the following represents the most significant zoonotic risk associated with this parasite in children?