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Difficulty: MediumInfectious Diseases

Evaluate the following distinct clinical vignettes detailing patients with specific environmental or occupational exposures. Match each patient's presentation with the most likely causative zoonotic pathogen.

  • A 45-year-old meatpacker presents with a 4-week history of undulating fevers, profuse night sweats, and joint pain. Examination reveals hepatosplenomegaly and diffuse lymphadenopathy.Brucella abortus
  • A 32-year-old farmer presents with sudden-onset high fever, retro-orbital headache, and a dry cough two weeks after assisting with lambing. Laboratory tests show elevated transaminases, but standard blood cultures are negative.Coxiella burnetii
  • A 28-year-old adventure racer presents with high fever, severe calf myalgias, and conjunctival suffusion one week after participating in an obstacle course through stagnant muddy water.Leptospira interrogans
  • A 55-year-old hunter presents with an indolent ulcer on his right index finger and painful swelling of his right axillary lymph nodes a week after skinning wild game.Francisella tularensis

Answer

The meatpacker with undulating fevers matches with Brucella abortus. The farmer with retro-orbital headache and hepatitis after lambing matches with Coxiella burnetii. The adventure racer with conjunctival suffusion matches with Leptospira interrogans. The hunter with an ulceroglandular presentation matches with Francisella tularensis.
Each zoonotic pathogen possesses a distinct epidemiological niche and clinical signature. Brucella abortus is associated with meatpackers and unpasteurized dairy, causing undulating fevers and reticuloendothelial spread. Coxiella burnetii is aerosolized during livestock birthing, leading to Q fever. Leptospira interrogans is found in water contaminated by animal urine, classically causing conjunctival suffusion and myalgias. Francisella tularensis is transmitted via ticks or handling infected animals like rabbits, resulting in ulceroglandular disease.

Step-by-Step Solution

1
Identify the unique occupational or recreational exposure in each clinical vignette.
Meatpacking points to Brucella; lambing to Coxiella; stagnant mud/water to Leptospira; skinning wild game to Francisella.
Zoonotic pathogens have highly specific epidemiologic risk factors and transmission vectors.
2
Correlate the physical exam and laboratory findings with the suspected pathogen.
Undulating fevers and hepatosplenomegaly confirm Brucellosis. Culture-negative hepatitis and pneumonia confirm Q fever. Conjunctival suffusion and calf pain confirm Leptospirosis. Ulceroglandular disease confirms Tularemia.
Ensuring the clinical syndrome matches the epidemiological suspicion prevents misdiagnosis among diseases that may share generalized febrile symptoms.

Key Concept

Zoonotic Infectious Diseases: Epidemiological Exposures and Clinical Syndromes
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Topics

Infectious Diseases

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