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Ehrlichiosis and Anaplasmosis: Data and Statistics

Due to the close relationship between the bacteria, cases of ehrlichiosis and anaplasmosis are currently reported together in Indiana. Most of the cases reported on this page are due to ehrlichiosis.

In 2017, 39 cases of ehrlichiosis and anaplasmosis were reported in Indiana, for an incidence rate of 0.58 cases per 100,000 population. For the five-year reporting period from 2013 to 2017, 180 cases of ehrlichiosis and anaplasmosis and anaplasmosis were reported (Figure 1). While the disease is most common in summer months when ticks are active, cases are also reported in the spring and fall (Figure 2). Ehrlichiosis and anaplasmosis can occur in all areas of Indiana, but most cases occur in the southern part of the state. People who live in or travel to this part of the state are at increased risk for developing ehrlichiosis and anaplasmosis. Figure 3 depicts cases of ehrlichiosis and anaplasmosis by county of residence.

Figure 1. Ehrlichiosis and Anaplasmosis Cases by Year — Indiana, 2013–2017

Figure 2. Ehrlichiosis and Anaplasmosis Cases by Month of Illness Onset – Indiana, 2017

Figure 3. Ehrlichiosis and Anaplasmosis Case Counts by County of Residence – Indiana, 2017

NOTE: These data include confirmed and probable cases according to national surveillance case definitions adopted by the Council of State and Territorial Epidemiologists (CSTE). The ehrlichiosis and anaplasmosis case definition may be found here. All rates are calculated per 100,000 population based on the U.S. Census Bureau’s population estimates as of July 1, 2017, obtained on July 10, 2018.


For prior years’ ehrlichiosis and anaplasmosis statistics, please visit our annual report pages.


Page Last Updated: October 9, 2018

Page Last Reviewed: October 9, 2018