A 21-year-old man comes to the emergency department due to shortness of breath, fatigue, myalgias, and debilitating retroorbital headaches for the past several days. The patient is on summer break and came to work at his grandparents' dairy farm 3 weeks ago. He cleans out animal waste from the barn, but he does not handle hay. His past medical history is insignificant. He does not use tobacco or illicit drugs. The patient's temperature is 38.8 C (101.8 F). Bronchial breath sounds are heard in the right lower lung. There are no cardiac murmurs. Abdominal examination is unremarkable. Chest x-ray demonstrates right lower and middle lobe consolidation. Laboratory results are as follows: An HIV test is negative.Which of the following is the most likely cause of this patient's symptoms?

Question

A 21-year-old man comes to the emergency department due to shortness of breath, fatigue, myalgias, and debilitating retroorbital headaches for the past several days.  The patient is on summer break and came to work at his grandparents' dairy farm 3 weeks ago.  He cleans out animal waste from the barn, but he does not handle hay.  His past medical history is insignificant.  He does not use tobacco or illicit drugs.  The patient's temperature is 38.8 C (101.8 F).  Bronchial breath sounds are heard in the right lower lung.  There are no cardiac murmurs.  Abdominal examination is unremarkable.  Chest x-ray demonstrates right lower and middle lobe consolidation.  Laboratory results are as follows:  An HIV test is negative.Which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

Q fever is a zoonosis caused by Coxiella burnetii. Human infection usually occurs through inhalation of bacteria from air contaminated by animal waste. Q fever has acute and chronic stages. Acute Q fever manifests as a nonspecific febrile illness with fever lasting >10 days, fatigue, and myalgias. Severe debilitating headaches, which are often retroorbital and associated with photophobia, are a frequent symptom. Pneumonia is one of the primary signs of acute Q fever, and the most common x-ray abnormality is lobar consolidation. Leukocyte count is often normal. Other classic laboratory findings are increased liver enzymes and thrombocytopenia. Chronic Q fever, which is frequently fatal if not treated, is rare, may occur in patients with or without previous symptomatic acute infection, and manifests as infective endocarditis in patients with valvular disease. (Choice A) Borrelia burgdorferi is a spirochete that is the causative agent in Lyme disease, transmitted to humans through the bite of the Ixodes tick. Manifestations include erythema migrans (target lesion), febrile illness with headaches and joint pains, and central nervous system or cardiac involvement. Pneumonia would be unusual. (Choice C) Epstein-Barr virus causes infectious mononucleosis (malaise, pharyngitis, splenomegaly). (Choice D) Escherichia coli can infect the udders of cows and cause infection of unpasteurized milk, but it is unlikely to cause a febrile illness with retroorbital headaches and pneumonia. (Choice E) Salmonellosis typically causes a gastrointestinal illness with abdominal cramps and diarrhea. Educational objective: Q fever is a zoonotic infection that occurs in farm workers exposed to waste from cattle and sheep. Its causative agent is Coxiella burnetii. A patient with exposure to waste from farm animals who develops a nonspecific illness (myalgias, fatigue, fever [>10 days], retroorbital headache) with a normal leukocyte count, thrombocytopenia, and increased liver enzymes should be evaluated for acute Q fever infection. __________ References: Diagnosis and management of Q fever - United States, 2013: recommendations from CDC and the Q Fever Working Group. (http://www.ncbi.nlm.nih.gov/pubmed/23535757)

A 21-Year-Old Man Comes to the Emergency Department Due to Shortness