DVM Zoonotic Diseases and Public Health 4 — Questions and Answers
Question 1: Which tickborne disease, caused by Anaplasma phagocytophilum, is considered zoonotic and shares its vector with Lyme disease in the northeastern US?
- Rocky Mountain spotted fever
- Human granulocytic anaplasmosis (HGA) (Correct answer)
- Ehrlichiosis (HME)
- Babesiosis
Correct answer: Human granulocytic anaplasmosis (HGA)
Anaplasma phagocytophilum causes human granulocytic anaplasmosis and is transmitted by Ixodes scapularis, the same tick that transmits Borrelia burgdorferi.
Question 2: A veterinarian suspects Yersinia pestis (plague) in a prairie dog colony in New Mexico. Appropriate immediate public health actions include:
- Relocating prairie dogs to unaffected areas to prevent colony collapse
- Notifying public health authorities and applying insecticide to reduce flea populations (Correct answer)
- Treating prairie dogs with antibiotics in the field to reduce reservoir burden
- Fencing the area to prevent human access without notifying health authorities
Correct answer: Notifying public health authorities and applying insecticide to reduce flea populations
Plague control requires immediate notification of public health authorities and flea reduction, as fleas are the primary transmission vector and insecticide application interrupts the cycle.
Question 3: Cat scratch disease (CSD) is caused by Bartonella henselae. Which clinical scenario represents the HIGHEST risk for severe or systemic disease?
- A healthy 10-year-old scratched by a kitten developing a local lymphadenopathy
- An HIV-positive adult scratched by a flea-infested kitten developing bacillary angiomatosis (Correct answer)
- A veterinarian bitten by an adult cat with regional lymph node swelling
- A healthy adult developing Parinaud's oculoglandular syndrome after kitten exposure
Correct answer: An HIV-positive adult scratched by a flea-infested kitten developing bacillary angiomatosis
Bartonella henselae causes bacillary angiomatosis—a severe, disseminated vascular proliferative disease—in immunocompromised individuals, particularly those with HIV/AIDS.
Question 4: Methicillin-resistant Staphylococcus aureus (MRSA) has been documented as a zoonosis. Which transmission pattern has been confirmed in companion animal households?
- MRSA is exclusively a hospital-acquired pathogen with no animal reservoir
- Bidirectional transmission between pets and their owners has been documented (Correct answer)
- Dogs and cats can harbor MRSA but cannot transmit it to humans under any circumstance
- MRSA is only transmitted from livestock to farm workers, not from companion animals
Correct answer: Bidirectional transmission between pets and their owners has been documented
Studies have confirmed bidirectional MRSA transmission between pets (dogs and cats) and their owners, with shared household strain types identified through molecular typing.
Question 5: Toxoplasma gondii oocysts in the environment primarily originate from which host, and what is the primary public health risk for pregnant women?
- Intermediate hosts (rodents); risk is via direct rodent contact
- Definitive hosts (felids); risk is congenital transmission causing fetal damage (Correct answer)
- Birds; risk is ingestion of undercooked poultry
- Cattle; risk is consumption of undercooked beef containing bradyzoites
Correct answer: Definitive hosts (felids); risk is congenital transmission causing fetal damage
Only felids shed infective oocysts; primary risk for pregnant women is congenital toxoplasmosis causing abortion, stillbirth, or severe fetal neurological damage.
Question 6: In the context of avian influenza surveillance, the term 'spillover event' refers to:
- Transfer of influenza virus between two wild bird species
- Transmission of an avian influenza strain to a mammalian (non-avian) host (Correct answer)
- Introduction of a human influenza strain into a domestic poultry flock
- Reassortment of influenza gene segments between two avian strains
Correct answer: Transmission of an avian influenza strain to a mammalian (non-avian) host
Spillover refers to interspecies transmission events where an avian influenza strain crosses from avian hosts into mammals, including pigs or humans, with pandemic potential.
Question 7: A confirmed human case of H5N1 highly pathogenic avian influenza (HPAI) is identified on a poultry farm. Under USDA/CDC coordination, veterinarians are responsible for:
- Providing treatment protocols for affected poultry to reduce human exposure
- Conducting epidemiological investigation and depopulation of infected flocks (Correct answer)
- Issuing prescriptions for oseltamivir to all farm workers as prophylaxis
- Quarantining only the individual human case without flock intervention
Correct answer: Conducting epidemiological investigation and depopulation of infected flocks
Veterinarians play a critical role in the One Health response by conducting flock investigations, confirming diagnosis, and overseeing humane depopulation to eliminate the source of human exposure.
DVM Zoonotic Diseases and Public Health 4
Which tickborne disease, caused by Anaplasma phagocytophilum, is considered zoonotic and shares its vector with Lyme disease in the northeastern US?