Acute Febrile Illness With Triple Co-Infection: A Case Report on the Diagnostic Challenges of Overlapping Febrile Illnesses.

A 35-year-old female presented with 5 days of fever, fatigue, and myalgia during the post-monsoon season at Damak Hospital, Jhapa, Nepal. Clinical examination revealed fever (102.7°F), tachycardia (110 bpm), and crackles in the right lower lung field. Laboratory investigations showed anemia (Hb 8.9 g%), leukopenia (3300/cumm), elevated liver enzymes (SGPT, 117 IU/L; SGOT, 94 IU/L; ALP, 391 U/L), and elevated CRP (18.58 mg/dL). ELISA testing demonstrated concurrent positivity for Salmonella typhi IgG/IgM, scrub typhus IgM, and Brucella abortus antigens. Blood and urine cultures were negative. Abdominal ultrasonography revealed hepatosplenomegaly. The patient initially received ceftriaxone and doxycycline, without any response. Following serological evidence of brucellosis, rifampicin 600 mg daily was added, and the patient became afebrile within 3 days. The patient was discharged on doxycycline 100 mg daily for 35 days and rifampicin 600 mg daily for 40 days. At 3-month follow-up, clinical examination and laboratory tests confirmed complete recovery. This case highlights the diagnostic challenges posed by serological cross-reactivity among endemic febrile illnesses in resource-limited settings, emphasizing the need for cautious test interpretations and clinical correlations.