Because the tick vector and geographic range for HGA is the same as that for Lyme disease, rarely the 2 may coexist in the same patient; doxycycline is effective therapy for both.
In October 2008, a report was made of an apparent nosocomial infection with A phagocytophilum that was transmitted from blood donated by an infected woman who had spent time in Minnesota just prior to donating.
The major antigenic determinants of Ehrlichia are surface membrane proteins. These antigenic proteins are complex and consist of thermolabile and thermostable components. In terms of kilodalton (kd) molecular weight, the key protein bands associated with HME are the 27-, 29-, and 44-kd bands. The major antigenic determinants associated with HGA include the 40-, 44-, and 65-kd bands.
In 1999, Buller et al reported 4 incidents of ehrlichiosis in Missouri due to Ehrlichia ewingii. [4] The associated disease may be clinically indistinguishable from infection caused by E chaffeensis or A phagocytophilum; however, laboratory testing can distinguish these incidents from HGA and HME.
Go to Tick Removal and Tick-Borne Diseases for complete information on these topics.
See 7 Bug Bites You Need to Know This Summer, a Critical Images slideshow, for helpful images and information on various bug bites.
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Female Lone Star tick, Amblyomma americanum, found in the southeastern and Midatlantic United States. It is a vector of several zoonotic diseases, including human monocytic ehrlichiosis and Rocky Mountain spotted fever. Courtesy of the CDC/Michael L. Levin, PhD.
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Map of the United States showing the distribution of the Lone Star Tick, which is the principle vector for ehrlichiosis.
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Established and reported distribution of anaplasmosis vectors Ixodes scapularis and Ixodes pacificus, by county, in the United States from 1907-1996. Courtesy of the Division of Vector-Borne Infectious Diseases at the Centers for Disease Control and Prevention.
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Anaplasmosis incidence by age. Courtesy of the Centers for Disease Control and Prevention.
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Ehrlichiosis incidence by age. Courtesy of the Centers for Disease Control and Prevention.
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This graph displays the number of human cases of ehrlichiosis caused by Ehrlichia chaffeensis reported to the Centers for Disease Control and Prevention (CDC) annually from 2000 through 2016. *From 2000 to 2008, ehrlichiosis was included in the reporting category “human monocytic ehrlichiosis” in reports to the National Notifiable Diseases Surveillance System (NNDSS). **Since 2008, ehrlichiosis has been reported to the NNDSS under the categories “Ehrlichia chaffeensis infections,” “Ehrlichia ewingii infections,” and “Undetermined ehrlichiosis/anaplasmosis infections”, which include infections caused by Ehrlichia muris eauclairensis. Only E chaffeensis infections are shown above. Courtesy of the CDC (https://www.cdc.gov/ehrlichiosis/stats/index.html).
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This graph shows the number of ehrlichiosis cases caused by Ehrlichia chaffeensis reported from 2000 through 2016 by month of onset to illustrate the seasonal trends. Cases are reported in each month of the year, although most are reported in June and July. Courtesy of the CDC (https://www.cdc.gov/ehrlichiosis/stats/index.html).
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This graph shows the number of US ehrlichiosis cases caused by Ehrlichia chaffeensis and reported to the CDC from 2000 to 2018. Courtesy of the CDC (https://www.cdc.gov/ehrlichiosis/stats/).
