Fever of unknown origin: Subacute thyroiditis versus typhoid fever

Fever of unknown origin (FUO) is not infrequently a diagnostic dilemma for clinicians. Common infectious causes include endocarditis and abscesses in adults, and noninfectious causes include neoplasms and certain collagen vascular diseases, for example, polymyalgia rheumatica, various vasculitides, and juvenile rheumatoid arthritis (adult Still℉s disease). Subacute thyroiditis is a rare cause of FUO. Among the infectious causes of FUO, typhoid fever is relatively uncommon. We present a case of FUO in a traveler returning from India whose initial complaints were that of left-sided neck pain and angle of the jaw pain, which initially suggested the diagnosis of subacute thyroiditis. After an extensive FUO workup, when typhoid fever is a likely diagnostic possibility, an empiric trial of anti-Salmonella therapy has diagnostic and therapeutic significance. The presence of relative bradycardia, and response to quinolone therapy, was the basis of the clinical diagnosis of typhoid fever as the explanation for this patient℉s FUO. This case illustrates the diagnostic difficulties in assessing patients with FUO with few diagnostic findings.