Does E. ewingii Cause More Cases of Ehrlichiosis Than Previously Thought?

This figure shows the incidence of ehrlichicosis cases by state in 2010 per million persons. Ehrlichiosis was not notifiable in Alaska, Colorado, the District of Columbia, Hawaii, Idaho, Iowa, Nevada, New Mexico, North Dakota or Montana. The incidence rate was zero for Arizona, Connecticut, Indiana, Massachusetts, Oregon, South Dakota, Utah, Vermont, Washington, and Wyoming. Incidence ranged between 0.03 to 1 case per million persons for California, Florida, Louisiana, Michigan, Ohio, Pennsylvania, Rhode Island and Texas. Annual incidence ranged from 1 to 3.3 cases per million persons in Alabama, Georgia, Illinois, Kansas, Maine, Minnesota, Mississippi, Nebraska, New Hampshire, New York, South Carolina and West Virginia. The highest incidence rates, ranging from 3.3 to 26 cases per million persons were found in Arkansas, Delaware, Kentucky, Maryland, Missouri, New Jersey, North Carolina, Oklahoma, Tennessee, Virginia, and Wisconsin.

Image and text credit: The US Centers for Disease Control and Prevention webpage on Statistics and Epidemiology of Ehrlichiosis. Link

Ehrlichiosis is caused by three species of bacteria belonging to the genus Ehrlichia: E. chaffeensis, E. ewingii and the provisionally named E. muris like (EML). A recent article in the CDC’s EID indicates that the proportion of cases attributable to E. ewingii may be higher than what we initially knew it to be.


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