Acute endocarditis, lymphadenitis, and bone marrow involvement in hemophagocytic syndrome have been newly identified as Q fever foci, according to study results published in JAMA Network Open.

The results also indicated that cardiovascular infections were the main fatal complications of Q fever, emphasizing the need for routine cardiovascular screening during acute Q fever.

The study included data on patients treated at the French National Reference Center for Q fever from January 1, 1991 to December 31, 2016. Participants had serologic findings that were positive for Coxiella burnetii, the causative vector of Q fever, and clinical data consistent with C burnetii infection (n=2434).

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Overall, 1806 participants presented with acute Q fever; 138 had acute Q fever that progressed to persistent C burnetii infection, and 766 had persistent focalized C burnetii infection.

The researchers identified rare and previously overlooked foci of infections, including lymphadenitis (4.0%, n=97) and alithiasic cholecystitis (.4%, n=11).

After analysis, the researchers found that vascular infection (hazard ratio [HR], 3.1; 95% CI, 1.7-5.7; P <.001) and endocarditis (HR, 2.4; 95% CI, 1.1-5.1; P =.02) were associated with an increased risk for death. They identified 2 independent predictors of lymphoma: lymphadenitis (HR, 77.4; 95% CI, 21.2-281.8; P <.001) and hemophagocytic syndrome (HR, 19.1; 95% CI, 3.4-108.6; P <.001).

The investigators recommend routine screening for anticardiolopin antibodies during acute Q fever, as it may aid in the prevention of cardiac complications. “A PET scan could be performed for all patients with suspected persistent focalized infection for early diagnosis of vascular and lymphatic infections associated with death and lymphoma, respectively,” the researchers wrote.

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Melenotte C, Protopopescu C, Million M, et al. Clinical features and complications of Coxiella burnetii infections from the French National Reference Center for Q fever. [published online August 24, 2018]. JAMA Network Open. doi:10.1001/jamanetworkopen.2018.1580