Approach Considerations
Moderately or severely ill patients may require hospitalization for diagnosis and treatment. Early treatment is critical. Consider the possibility of ehrlichiosis when patients have a febrile illness and a history of recent tick exposure. Doxycycline remains the preferred drug for persons with ehrlichiosis. [1, 2]
Continue treatment until the patient has been afebrile for at least 3 days and for 10-14 days depending on the severity of illness. Guidelines for the diagnosis and management of tick-borne diseases have been established by the CDC. [2]
Deterrence and Prevention
Deterrence and prevention of ehrlichiosis includes the following:
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Wear light-colored clothes
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Tuck pants into socks
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Use insect repellent
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Regularly examine the body for ticks
Promptly remove ticks; a feeding period of 3-48 h is required before disease is transmitted. Cover exposed areas of the skin with insect repellents containing N,N -diethyl-meta-toluamide (DEET). In children, carefully use insect repellents on exposed skin; avoid the face and hands to prevent systemic absorption.
After returning from wooded and/or tick-infested areas, individuals should check themselves carefully for ticks. If found, ticks should be removed carefully and a physician should be consulted.
Any of several commercial devices should be used, if possible, to remove ticks. Alternatively, ticks can be removed by grasping them with fine tweezers at the point of attachment and pulling slowly and steadily. The aim is to remove the mouthparts from the site of insertion without damaging the insect.
After removal, the skin should be disinfected. Check to make sure that the tick head is not still embedded.
Some have recommended keeping the tick in a jar along with a damp paper towel in the refrigerator for a month or so, in case symptoms develop, as it may help to identify what (if any) infection has been transmitted.
Trying to burn the tick; smothering it in alcohol, petroleum jelly, or similar substance; or twisting or rubbing the tick off is not recommended. These methods have not been shown to decrease the time the tick remains embedded and risk breaking the tick body open and releasing otherwise-contained bacteria.
No role exists for the use of antimicrobial prophylaxis after a tick bite in the prevention of human monocytic ehrlichiosis (HME) or human granulocytic anaplasmosis (HGA) due to the low rate of subsequent infection.
Consultations
An infectious disease specialist should be consulted for any patient with an acute febrile illness and a recent history of tick exposure.
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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/).
Tables
|
Human monocytic ehrlichiosis (HME) |
Human granulocytic anaplasmosis (HGA) |
Cell type Affected |
Monocytes |
Granulocytes |
Organism |
E chaffeensis |
A phagocytophilum |
Vector |
Amblyomma americanum (Lone Star tick) |
Ixodes scapularis (black-legged tick), Ixodes pacificus (Western black-legged tick) in California, Ixodes ricinus in Europe, and probably Ixodes persulcatus in parts of Asia |
Location |
Southeastern and south-central United States |
Wisconsin and Minnesota, less active in New York and Connecticut, also California |
Rash |
30% of adults, 60% of children |
Rare |
Prognosis |
~3% mortality |
< 1% mortality |
