Q Fever - The Intersection of Rheum and ID Save

Today in clinic, I saw a patient with longstanding seropositive, erosive rheumatoid arthritis who had been treated with etanercept for over 10 years. She had undergone valve replacement years ago for regurgitation. Approximately 2 years ago she had onset of fevers, chills, night sweats, in addition to weight loss and shortness of breath.

These symptoms prompted an echo followed by a transesopheal echo, which was consistent with prosthetic valve endocarditis with severe valvular regurgitation. Ultimately, she underwent redo aortic valve replacement. Valve pathology revealed mild inflammation and silver stain showed intracellular coccobacilli. Upon further questioning, the patient indicated that several years ago for one summer she had unpasteurized milk delivered from a farm share in New York. Coxiella burnetii titers were high and her picture was consistent with chronic Q fever. 

To orient you, I am completing my 3rd year of a combined fellowship in rheumatology and infectious disease and hope to craft a career that joins the two fields. This case perfectly exemplifies the marriage of rheum and ID and got me thinking, who gets Q fever?

A quick literature review led me to a letter published in the Annals of Rheumatic Disease in July, 2014, where a group from the Netherlands examined the seroprevalence of C. burnetii infection in RA patients (who were living in a Q fever endemic area after an outbreak) receiving anti-TNF therapy versus biologics (http://ard.bmj.com/content/73/7/1436 ). They found equal rates of infection in patients on anti-TNF and DMARDs and observed that the prevalence of chronic Q fever infection in RA patients was higher (8.9%) that previously reported in non RA patients in the same area (1.6%),  concluding that RA patients are at increased risk of chronic Q fever regardless of treatment. 

Q fever is uncommon in the U.S. (~40 cases/yr) and the classic risk factors are consumption of unpasteurized milk and animal exposure (cow famers, veterinarians, etc.). Q fever can present with a wide spectrum of manifestations and can be acute or chronic. Acute Q fever presents with high fever, headache and flu-like symptoms and the chronic form with endocarditis, mycotic aneurysm or infected vascular graft and is fatal if untreated.

Diagnosis is made by serology as C. burnetii does not grow on routine culture. While uncommon, this case reminded me of the bizarre infections that may manifest in our immunosuppressed patients and the importance of taking a thorough history.