Diagnostic Approach for Chronic Malaise and Occasional Feverishness
Initial Assessment and Laboratory Testing
- The Centers for Disease Control and Prevention recommends a thorough diagnostic approach for chronic malaise and occasional feverishness, including serologic testing for Q fever, complete blood count, inflammatory markers, and targeted imaging based on clinical findings to identify the underlying cause, with risk factors for chronic infections such as heart valve defects, vascular grafts, aneurysms, and immunosuppression considered 1
- The National Comprehensive Cancer Network recommends first-line laboratory tests, including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), for patients with chronic malaise and occasional feverishness 2
- Serologic testing for Q fever, including phase I and II IgG and IgM antibodies by immunofluorescent assay, is recommended for patients with suspected Q fever 1, 3
Imaging Studies and Specialized Testing
- The National Comprehensive Cancer Network recommends chest radiography as an initial screening tool, and consider contrast-enhanced CT of chest, abdomen, and pelvis if initial workup is unrevealing, for patients with chronic malaise and occasional feverishness 2
- Echocardiography is recommended if there is suspicion of endocarditis or valvular disease 1
- PCR testing for suspected pathogens is recommended for patients with chronic malaise and occasional feverishness 3
- Autoimmune markers, such as those for autoimmune disease, are recommended for patients with suspected autoimmune disease 4
Specific Diagnostic Considerations and Follow-up
- For suspected Q fever, a testing algorithm is recommended, including acute phase (≤14 days): PCR on whole blood, 14-21 days: IFA for phase I and II IgG and IgM; PCR, convalescent phase (3-6 weeks after acute sample): IFA for phase I and II IgG and IgM, and chronic phase (>6 weeks): IFA for phase I and II IgG and IgM; PCR 3
- A phase I IgG titer ≥1:1024 with clinical evidence of organ infection suggests chronic Q fever 1, 3
- The American Academy of Allergy, Asthma, and Immunology recommends evaluation for autoinflammatory syndromes if recurrent fevers with characteristic patterns, rash, arthritis, or abdominal pain during episodes, and family history of similar symptoms are present 4