Human ehrlichioses are tick-borne diseases that have been increasing in incidence in the United States during recent years. Ehrlichia chaffeensis is one of the primary bacteria that cause ehrlichiosis in humans, which typically results in fever-like symptoms, but may also be fatal if left untreated. E. chaffeensis infections are reported to the Centers for Disease Control and Prevention (CDC) through the National Notifiable Diseases Surveillance System (NNDSS). This study analyzed the cases of E. chaffeensis infections reported by the NNDSS from 2012 through 2016. There were 6786 cases and the incidence rate was 4.46 cases per million persons per year. The demographic group most commonly infected was white males between the ages of 40 and 64. Infections were most abundant in the southeast and midwest, particularly in Arkansas, Missouri, Tennessee, and Oklahoma, as well as much of the east coast. The number of cases reported each year from 2012 through 2016 was higher than the number reported in any of the previous 4 years. Ongoing surveillance and reporting of tick-borne diseases are critical to inform public health practice and guide disease treatment and prevention efforts.
Keywords: Centers for Disease Control and Prevention (CDC); National Notifiable Diseases Surveillance System (NNDSS); human ehrlichiosis; incidence rate; spatial epidemiology.