Babesiosis, 2016

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 Ixodes scapularis (the blacklegged tick or deer tick), the same vector that transmits the agents of Lyme disease, Anaplasmosis, one form of human ehrlichiosis, and 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, other co-morbidities, and the elderly may become seriously ill.

In 2016, 50 confirmed and probable babesiosis cases (0.9 per 100,000 population) were reported, up from the 45 cases in 2015. Despite slight annual fluctuations, case totals since 2005 (range, 10 to 72) have been consistently higher than reported totals from 1996 to 2004 (range, 0 to 9) (Figure 1). In 2016, 28 (56%) of the cases occurred in males. The median case age was 61 years (range, 3 to 88 years), down from 64 in 2015, and older than the median ages for both anaplasmosis (59 years) and Lyme disease (49 years). Onsets of illness peaked in the summer months; 38 (76%) of 50 patients with known onset reported first experiencing symptoms in June, July, or August. Fifteen (30%) cases were hospitalized for their infection in 2016 for a median duration of 5 days (range, 2 to 13 days). Although severe complications like organ failure were reported in 6 cases, there were no deaths attributable to babesiosis in 2016.

• For up to date information see>> Babesiosis (Babesia microti)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2016