421. Babesiosis: Retrospective Review of 38 Cases from Upper Midwest

BACKGROUND: Babesiosis is a tick-borne illness caused by protozoal infection of the genus Babesia. Clinical presentation varies widely from asymptomatic to rapidly fatal infection and diagnosis requires a high index of clinical suspicion. It is an emerging health risk and clinicians need to be aware of its different clinical manifestations. METHODS: We retrospectively collected and analyzed data from 38 patients with babesiosis from 1990 to 2015. RESULTS: Mean age of patients was 63 years. 68% of patients required hospitalization with 21% requiring intensive care unit (ICU) stay. Mean length of illness before diagnosis was 15.6 days and symptoms comprised of malaise (82%), subjective fever (71%), chills (55%), anorexia (29%), arthralgia (29%), and nausea (16%). Only 47% of the patients recalled tick bites. Mean hemoglobin in the outpatients was 12.4 g/dL compared with 9.8 g/dL in the hospitalized patients (P < 0.01). Among hospitalized patients, mean hemoglobin for ICU admissions was 7.5 g/dL vs. 10.9 g/dL (P < 0.01) for those without ICU stay. Mean parasitemia was 10.1% in those requiring ICU compared with 1.4% in those admitted to the medical floor (P < 0.01). 28.9% had Lyme disease, and 10.5% had anaplasma coinfection. Co-morbidities included diabetes mellitus (n = 3), asplenia (n = 5), and immunosuppression (n = 3). Diagnosis was made with PCR and peripheral smear in 50% of patient whereas 50% were diagnosed with PCR alone. In 27% of patients with positive PCR, peripheral smear was negative. All patients with asplenia required hospitalization with 3/5 requiring ICU with initial parasitemia ranging from 2.5 to 28% and duration of parasitemia ranging from 10 to 142 days. Initial treatment comprised of clindamycin plus quinine in 31% of patients whereas combination of atovaquone and azithromycin was used in 69% of patients. Median duration of treatment was 10 days. Overall three patients underwent exchange transfusion with parasitemias ranging from 12.3 to 28.5%. None of the patients died during hospitalization. CONCLUSION: Less than half of the patients with babesiosis recall tick bites. There is usually a delay in diagnosis of up to 2 weeks due to nonspecific nature of symptoms. In more than one-fourth of patients with babesiosis peripheral smear may be falsely negative. Hemoglobin and percentage parasitemia seemed to correlate with severity of illness. DISCLOSURES: All authors: No reported disclosures.