Babesiosis, 2015

Babesiosis is a malaria-like illness caused by a protozoan, typically Babesia microti, which infects red blood cells. B. microti is transmitted to humans by bites from I. scapularis (the blacklegged tick or deer tick), the same vector that transmits the agents of Lyme disease, Anaplasmosis, one form of human ehrlichiosis, and a strain of Powassan virus. Babesia parasites can also be transmitted by blood transfusion. Babesia infections can range in severity, and while most people have asymptomatic infections, people with weak immune systems, underlying health conditions, and the elderly may become seriously ill.

In 2015, 45 confirmed and probable cases (0.8 per 100,000 population) were reported, down from the 49 reported cases in 2014 (Figure 1). Despite this decrease, yearly case totals since 2005 (range, 10 to 72) have been consistently higher than reported totals from 1996 to 2004 (range, 0 to 9). In 2015, 26 (58%) of the babesiosis cases reported occurred in males. The median case age was 64 years (range, 8 to 85 years), older than the median ages for both anaplasmosis (58 years) and Lyme disease (44 years). Onsets of illness peaked in the summer months; 36 (80%) reported first experiencing symptoms in June, July, or August. Nineteen (42%) cases were hospitalized due to their infection for a median duration of 5.5 days (range, 3 to 14 days). Although severe complications such as organ failure were reported in 9 cases, there was only 1 death attributable to babesiosis in 2015.

• For up to date information see>> Babesiosis (Babesia microti)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2015