Fever of unknown origin (FUO) due to babesiosis in a immunocompetent host

• Published in: Heart & lung Vol. 37; no. 6; pp. 481 - 484
• Main Authors: Cunha, Burke A., MD, Cohen, Yehuda Z., MD, McDermott, Brian, DO
• Format: Journal Article
• Language: English
• Published: United States Mosby, Inc 01.11.2008; Elsevier Science Ltd
• Subjects: Aged; Animals; Anti-Bacterial Agents - therapeutic use; Atovaquone - therapeutic use; Babesia - isolation & purification; Babesiosis - complications; Babesiosis - diagnosis; Babesiosis - drug therapy; Cardiovascular; Critical Care; Drug Therapy, Combination; Erythrocytes; Fever; Fever of Unknown Origin - etiology; Fever of Unknown Origin - physiopathology; Follow-Up Studies; Humans; Immunocompetence; Immunoglobulins; Infectious diseases; Intensive Care Units; Male; Medical diagnosis; Parasites; Pulmonary/Respiratory; Radiography, Thoracic; Rare Diseases; Risk Assessment; Severity of Illness Index; Treatment Outcome; United States > US
• ISSN: 0147-9563; 1527-3288
• DOI: 10.1016/j.hrtlng.2008.01.003

Fevers of unknown origin (FUOs) are defined as prolonged fevers of 101°F or greater lasting 3 or more weeks that remain undiagnosed after comprehensive inpatient/outpatient laboratory testing. Tick-borne infections are uncommon causes of FUOs. Any infectious disease accompanied by prolonged fevers can present as an FUO if the diagnosis is not suspected or if specific laboratory testing is not done to confirm the diagnosis. Babesiosis is transmitted by the Ixodes scapularis ticks endemic to areas in the northeastern United States. We present the case of a 73-year-old, non-human immunodeficiency virus, male from Long Island who presented with FUO for 6 weeks. As with malaria, there are usually few or no localizing signs in babesiosis. During the patient's hospitalization, babesiosis was suspected on the basis of nonspecific laboratory findings, that is, relative lymphopenia, thrombocytopenia, thrombocytopenia, and an elevated lactate dehydrogenase. When babesiosis was considered in the differential diagnosis, stained blood smears demonstrated the red blood cell inclusions of babesiosis. In the hospital, the patient developed noncardiac pulmonary edema, which rapidly resolved which has been described as a rare complication of babesiosis. He also had an elevated immunoglobulin-M Lyme titer indicating coinfection with Lyme disease. Although his hemolytic anemia persisted for weeks, he only had 3% parasitemia and intact splenic function. We believe this to be the first case of babesiosis presenting as an FUO in a normal host.