TABLE 1.

Dutch consensus guidelines on chronic Q fever diagnosis^a

Diagnosis	Characteristicsb
Proven chronic Q fever	Positive Coxiella burnetii PCR in blood or tissuec OR an IFA titer of ≥800 or 1,024 for C. burnetii phase I IgGd with either definite endocarditis according to the modified Duke criteria (19) or proven large vessel or prosthetic infection by imaging studies (FDG-PET [18], CT, MRI, or AUS)
Probable chronic Q fever	IFA titer of ≥800 or 1,024 for C. burnetii phase I IgGc AND valvulopathy not meeting the major criteria of the modified Duke criteria (19) OR known aneurysm and/or vascular or cardiac valve prosthesis without signs of infection by imaging studies (TEE/TTE, FDG-PET [18], CT, MRI, or AUS) OR suspected osteomyelitis, pericarditis, or hepatitis as manifestations of chronic Q fever OR pregnancy OR symptoms and signs of chronic infection such as fever, weight loss, night sweats, hepatosplenomegaly, and persistent raised ESR and CRP OR granulomatous tissue inflammation as proven by histological examination OR immunocompromised state
Possible chronic Q fever	IFA titer of ≥800 or 1,024 for C. burnetii phase I IgGd without manifestations meeting the criteria for proven or probable chronic Q fever

^aSee reference 15.

^bIFA, immunofluorescence assay; FDG-PET, fluorodeoxyglucose positron emission tomography; CT, computed tomography; MRI, magnetic resonance imaging; AUS, abdominal ultrasound; TEE, transesophageal echocardiography; TTE, transthoracic echocardiography.

^cIn the absence of acute infection.

^dCutoff is dependent on the IFA technique used (developed in-house or a commercial IFA technique, respectively).