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Causes
By Mayo Clinic staff
Ehrlichiosis is caused by Ehrlichia chaffeensis bacteria and is transmitted primarily by the Lone Star tick.
Ticks feed on blood, latching onto a host and feeding until they're swollen to many times their normal size. During feeding, ticks that carry disease-producing bacteria can transmit the bacteria to a healthy host. Or they may pick up bacteria themselves if the host, such as a white-tailed deer or a coyote, is infected.
Usually, to get ehrlichiosis, you must be bitten by an infected tick. The bacteria enter your skin through the bite and eventually make their way into your bloodstream.
Before bacteria can be transmitted, a tick must be attached and feeding for at least 24 hours. An attached tick with a swollen appearance may indicate that the tick has been feeding long enough to have transmitted bacteria. Removing ticks as soon as possible may prevent infection.
It's also possible that ehrlichiosis may be transmitted through blood transfusions, from mother to fetus and through direct contact with an infected, slaughtered animal.
- Ehrlichiosis. Centers for Disease Control and Prevention. http://www.cdc.gov/ehrlichiosis. Accessed May 3, 2012.
- Other tick-borne diseases. American Lyme Disease Foundation. http://www.aldf.com/Ehrlichiosis.shtml. Accessed May 3, 2012.
- Hay WW, et al. Current Diagnosis & Treatment: Pediatrics. 20th ed. New York, N.Y.: The McGraw-Hill Companies; 2011. http://www.accessmedicine.com/content.aspx?aID=6589902. Accessed May 3, 2012.
- Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/content.aspx?aID=9102446. Accessed May 3, 2012.
- Graham J, et al. Tick-borne illnesses: CME update. Pediatric Emergency Care. 2011;27:141.
- Ismail N, et al. Human ehrlichiosis and anaplasmosis. Clinical Laboratory Medicine. 2012;30:261.
- Lyme disease. American Lyme Disease Foundation. http://www.aldf.com/lyme.shtml#removal. Accessed May 4, 2012.
- Preventing tick bites. Centers for Disease Control and Prevention. http://www.cdc.gov/ticks/avoid/on_people.html. Accessed May 4, 2012.
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