Fevers of unknown origin (FUOs) are defined as prolonged
fevers of 101 degrees 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.