PYREXIA OF UNKNOWN ORIGIN (PROLONGED PYREXIA)
Pyrexia of unknown origin (PUO) is defined as any fever fulfilling following criteria:
• Fever of gt;14 days duration,
• Fever documented in the hospital,
• Cause remains unidentified even after one week of routine investigations in the hospital.
Etiology: PUO usually indicates presence of a chronic infection, immunological disorder or malignancy (Table 10.2). Infections account for more than half of these cases and five commonest causes in Indian children are: (a) enteric fever, (b) malaria, (c) tuberculosis, (d) urinary tract infection, and (e) infective hepatitis. In ~30%, diagnosis remains an enigma despite best laboratory support. Rheumatic disorders (~10%) and malignancies (~5%) are emerging as important causes of PUO after easier availability of diagnostic tests for common infections.
Diagnostic approach in prolonged pyrexia depends on:
(a) epidemiological risk of diseases in local population,
(b) review of case history, including prior medications and investigations, (c) re-assessment of clinical examination for missed/new findings and (d) baseline and
| TABLE 10.2: Causes of prolonged pyrexia (PUO) in children | |
| Infectious causes | Non-infectious causes |
| 1. Bacterial | 1. Immunological |
| Enteric fever | Rheumatic fever |
| Urinary tract infection | Collagen disorders: JRA, SLE |
| Infective endocarditis | Chronic active hepatitis |
| Brucellosis | Chronic inflammatory bowel |
| Deep-seated abscess | diseases |
| Bone/joint infection | 2. Neoplasms |
| 2. Viral | Leukemia |
| Viral hepatitis | Lymphoma |
| HIV | Solid tumors |
| Infectious mononucleosis | 3. Neurological |
| 3. Parasitic | Autonomic disorders[***] [†††] |
| Malaria | Hypothalamic lesions |
| Amebic hepatitis | 4. Endocrinal |
| 4. Miscellaneous | Hyperthyroidism |
| Leptospirosis | Diabetes insipidus |
| Rickettsial fevers | 5. Miscellaneous |
| Opportunistic Infections | Fictitious fever Drug fever |
*e.g. Riley-Day syndrome
relevant investigations, as dictated by clinical suspicion (Table 10.3).
Management: Since many cases of PUO are non-infectious in origin, empirical antibiotics are not recommended and may obscure the diagnosis. Treatment is largely supportive and empirical trials, e.g. antitubercular therapy should be avoided.
10.1.2