Some individuals, particularly elderly individuals who are experiencing flu-like symptoms might be actually suffering from a malaria-like disease called babesiosis. A study by scientists at the U.S. Food and Drug Administration (FDA) and researchers from a consulting firm and the Centers for Medicare and Medicaid Services (CMS) found that elderly populations living in Connecticut, Rhode Island, New York, and Massachusetts had the highest rates of babesiosis among the elderly population and that such infections appear to be on rise in Maryland, Virginia, and the District of Columbia.
The study, which focused on babesiosis diagnosed among elderly (65 years of age and older) Medicare beneficiaries from 2006 through 2008, found that that the disease was diagnosed in this population most often during the summer. Overall, 41% of all cases were diagnosed during the months of July and August. This seasonal concentration of diagnosed cases is probably due to the transmission season of Babesia parasites and activity of the tick that carries Babesia. In addition, people are more likely to spend time outdoors during these months and be exposed to the tick.
The FDA scientists and their collaborators collected data on clinical babesiosis in this population from Medicare enrollment files, as well as data bases from various medical facilities, such as skilled nursing homes. The scientists used the data to estimate the number of cases of babesiosis per each 100,000 Medicare beneficiaries each year from 2006 through 2008.
The number of elderly Medicare patients (65 years of age and older) who had babesiosis from 2006 through 2008 was 985 in 2006, 851 in 2007, and 1,223 in 2008. That is equivalent to rates of 3.6/100,000 beneficiaries (2006), 3.2/100,000 (2007), and 4.7/100,000 (2008).
Annual rates of babesiosis were significantly higher for men versus women and for women aged 65-84 years compared to women 85 years and older. This was consistent with data previously collected by various state health agencies.
Annual rates among elderly whites were 4.0/100,000 (beneficiaries) (2006), 3.6/100,000 (2007), and 5.2/100,000 (2008). The rates among elderly nonwhites were 0.6/100,000 (2006), 0.9/100,000 (2007), and 1.4/100,000 (2008).
Babesiosis is caused by infection of red blood cells by a protozoan (a single-celled parasite) called Babesia which are closely related to the parasites that cause malaria. Babesia infections can be asymptomatic (no visible clinical disease) or cause mild, flu-like symptoms such as fever, chills and aches. Severe complications, including multi-organ failure, and death, occur mostly in people without a spleen, those with immune system dysfunction, and the neonates and elderly. The Babesia parasite is carried and spread by ticks, which acquire the parasite while feeding on infected mice or some other mammals.
The study is important because it suggests that large administrative healthcare databases such as those maintained by Medicare, state public health departments, and health insurance companies can be used to assess the risk of emerging infections in the United States.
“Babesiosis among Elderly Medicare Beneficiaries, United States, 2006-2008”
Emerging Infectious Diseases
Vol. 18, No. 1, January 2012
Mikhail Menis, Steven A. Anderson, Hector S. Izurieta, Sanjai Kumar, Dale R. Burwen, Mark Walderhaug (CBER, US Food and Drug Administration)
Jonathan Gibbs, Garner Kropp, Tugce Erten, Thomas E. MaCurdy (Acumen LLC, Burlingame, California)
Christopher M. Worrall and Jeffrey A. Kelman (Centers for Medicare & Medicare Services, Baltimore, MD)
While there are currently no FDA-approved laboratory tests to detect Babesia infections in blood donors, workers at blood collection centers can screen for potential donors who have ever had babesiosis. The current full-length donor history questionnaire specifically asks prospective donors if they have ever had babesiosis:
In addition, CBER held a workshop in September 2008 to discuss transfusion-transmitted babesiosis with experts:
CBER also sought advice on blood donor testing and screening strategies from its Blood Products Advisory Committee in July 2010:
CBER scientists are now working to develop two types of laboratory test that can differentiate between potential donors who are currently infected from those who were previously exposed to this parasite but are not currently infected.