Ehrlichiosis
Ehrlichiosis
What is ehrlichiosis?
Ehrlichiosis is a newly recognized and potentially life-threatening disease that is spread by ticks. Since 1986, two types of human ehrlichiosis have been identified in the United States: human monocytic ehrlichiosis (HME) and human granulocytic ehrlichiosis (HGE). The illnesses differ in the types of white blood cells they attack -- either monocytes or granulocytes.
What is the infectious agent that causes ehrlichiosis?
Ehrlichiosis is caused by specialized bacteria called rickettsiae. HME is caused by Ehrlichia chaffeensis. HGE is caused by a newly identified but as yet unnamed Ehrlichia.
Where is ehrlichiosis found?
In the United States, HME has so far been concentrated in the southeast and south-central regions. HGE has been found mainly in the upper midwestern and northeastern states, but also in northern California.
How do people get ehrlichiosis?
People get ehrlichiosis from the bite of an infected tick. Evidence suggests that the lone star tick transmits HME and that the deer tick transmits HGE. The deer tick also spreads Lyme disease and babesiosis.
What are the signs and symptoms of ehrlichiosis?
The disease is similar to Rocky Mountain spotted fever and can be severe and life-threatening. The most common symptoms are sudden high fever, tiredness, major muscle aches, severe headache, and, in some cases, a rash.
How soon after exposure do symptoms appear?
Symptoms usually appear 3 to 16 days after a tick bite.
How is ehrlichiosis diagnosed?
Diagnosis is difficult, even in severe cases. Special laboratory tests can detect recent infection with Ehrlichia bacteria. Because diagnostic tests are not widely available, the diagnosis of ehrlichiosis is usually based on symptoms and a history of exposure to ticks.
Who is at risk for ehrlichiosis?
Anyone can get ehrlichiosis, although most cases have been in adults. The risk of severe illness and complications is probably highest in older persons. People who spend time outside in tick-infested areas during the spring and summer are also at increased risk for exposure.
What complications can result from ehrlichiosis?
Severely ill patients can develop abnormally low numbers of white blood cells, abnormally low numbers of platelets, and kidney failure. Deaths have been reported for both HME and HGE. Ehrlichiosis does not appear to result in the long-term, arthritis-like symptoms sometimes associated with Lyme disease.
What is the treatment for ehrlichiosis?
Ehrlichiosis can be treated with antibiotics .
How common is ehrlichiosis?
It is not known how common HME and HGE are in the United States. Approximately 200 cases of HGE and 400 cases of HME have been confirmed. It is likely, however, that many more cases are untreated or misdiagnosed.
Is ehrlichiosis an emerging infectious disease?
Yes. Ehrlichiosis was shown to cause disease in people in 1986. Since then, HME and, later, HGE have emerged as major diseases in humans. Both the number of cases and their geographic range continue to increase.
How can ehrlichiosis be prevented?
No vaccine is available to protect humans against HME or HGE. You can reduce your risk by taking these precautions against tick bites:
This fact sheet is for information only and is not meant to be used for self-diagnosis or as a substitute for consultation with a health-care provider. If you have any questions about the disease described above or think that you may have ehrlichiosis, consult a health-care provider.