Malaria of the North: Outcomes of Human Babesiosis in Long Island, NY After Treatment Guidelines Revision

Background: Babesiosis is rare, potentially life-threatening, tick-borne infection endemic in Long Island, NY. The purpose of this study was to review recent trends in babesiosis management and outcomes as new drugs have been introduced and treatment guidelines have been revised.

Methods: A retrospective chart review of patients presented to Stony Brook University Hospital (SBUH) between 2008 and 2014 with peripheral blood smears positive for Babesia and charts of patients with positive Babesia serology (smears negative or unavailable) was performed. Clinical and epidemiological information was recorded and analyzed.

Results: Sixty two patients with confirmed babesiosis (presence of parasitemia) presented to SBUH over course of 7 years. Fifty three (85%) patients were hospitalized, 20 (32%) admitted to Intensive Care Unit, 1  (2%) died. Median age on admission was 62 years. Nine patients (15%) had prior splenectomy and 15 (24%) had a history of blood or other cancer. Majority of patients (60%) presented febrile (mean temperature 38.1C) with mean parasetemia of 3.44%. Thirteen patients (21%) were co-infected with Lyme disease. Most patients (92%) were treated with azithromycin and atovaquone with or without clindamycin and quinine. Twelve patients (19%) required exchange transfusion. Majority of patients (94%) improved and were discharged from hospital or clinic. 

Most of the patients with positive Babesia serology and negative/unavailable smear (n=38) presented for workup of febrile illness or were admitted to SBUH for unrelated reasons. Fever (50%), fatigue (53%) and headache (39%) were the most common symptoms. Only 7 patients (11%) in this group were co-infected with Lyme disease. One third of patients in serology group were treated for babesiosis with atovaquone and azithromycin without positive blood smear. All patient survived and were discharged.

Conclusion: Symptomatic babesiois is rare even in endemic regions. Majority of patients who presented with babesiosis to SBUH did not have prior splenectomy and more than half had only age related comorbidities. Novel treatment regimens for babesiosis are well tolerated and effective. Compared to historical controls we observed a lower overall mortality. Positive Babesia serology per se does not indicate disease and usually does not require treatment.