Babesiosis among Elderly Medicare Beneficiaries, United States, 2006–2008

Mikhail Menis

, Steven A. Anderson, Hector S. Izurieta, Sanjai Kumar, Dale R. Burwen, Jonathan Gibbs, Garner Kropp, Tugce Erten, Thomas E. MaCurdy, Christopher M. Worrall, Jeffrey A. Kelman¹, and Mark O. Walderhaug¹

Author affiliations: Food and Drug Administration, Rockville, Maryland, USA (M. Menis, S.A. Anderson, H.S. Izurieta, S. Kumar, D.R. Burwen, M.O. Walderhaug); Acumen LLC, Burlingame, California, USA (J. Gibbs, G. Kropp, T. Erten, T.E. MaCurdy); Centers for Medicare & Medicaid Services, Baltimore, Maryland, USA (C.M. Worrall, J.A. Kelman)

Abstract

We used administrative databases to assess babesiosis among elderly persons in the United States by year, sex, age, race, state of residence, and diagnosis months during 2006–2008. The highest babesiosis rates were in Connecticut, Rhode Island, New York, and Massachusetts, and findings suggested babesiosis expansion to other states.

Human babesiosis is a zoonotic disease caused by intraerythrocytic protozoan parasites of Babesia species. In the United States, Babesia microti is the primary etiologic agent of human babesiosis and is usually transmitted through the bite of Ixodes scapularis, the principal tick vector for this species (1–3). Human B. microti infections are regional, endemic to Northeastern (Connecticut, Rhode Island, Massachusetts, New York, New Jersey) and Midwestern (Minnesota, Wisconsin) states, and the geographic range is believed to be expanding (1,2,4,5). Babesiosis is characteristically seasonal, with peak transmission from May through September (1,2,6). In younger persons, babesiosis is more likely to be a mild or asymptomatic disease that may persist for months or even years undetected (1,2,7,8). Elderly, splenectomized, and other
immunocompromised persons tend to be symptomatic (e.g., fever, chills, fatigue) and at risk for complications, including hemolytic anemia, acute respiratory failure, renal failure, and death (1–3,9).

Recently, there has been an increase in the number of reported clinical and transfusion-transmitted babesiosis cases in the United States (1,2,10). Efforts to mitigate transfusion-transmitted babesiosis risk include development of donor screening tests and testing strategies. Initiatives on babesiosis encompassed addition of Babesia spp. infections to the list of nationally notifiable diseases in 2011, a Food and Drug Administration sponsored workshop (1), a Blood Products Advisory Committee Meeting (10), and creation of the AABB Babesia Task Force. Because elderly persons are one of the most vulnerable at-risk populations and there are no published nationwide studies on babesiosis in that group, we used Centers for Medicare & Medicaid Services (Baltimore, MD, USA) administrative databases to assess babesiosis among elderly Medicare beneficiaries in the United States during 2006–2008.