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What is ehrlichiosis?
- In the U.S., the term “ehrlichiosis” is the general name used to describe diseases caused by Ehrlichia chaffeensis, E. ewingii and E. muris eauclairensis.
- These bacteria are spread by infected ticks, including the lone star tick (Amblyomma americanum) and blacklegged ticks (Ixodes scapularis).
- The disease is characterized by fever, headache, chills, and muscle aches.
- The most effective treatment for people of all ages is doxycycline.
- The disease can be prevented by prompt tick removal.
Who is at risk?
- Anyone who lives or recreates where the tick species may be present could become infected.
- The majority of reported human illnesses are due to Ehrlichia chaffeensis.
- Ehrlichia chaffeensis and Ehrlichia ewingii are transmitted by the lone star tick (Amblyomma americanum) which is found from the southeastern and southcentral U.S. and from the eastern seaboard extending westward to Texas.
- Ehrlichia muris eauclairensis is carried by the blacklegged tick (Ixodes scapularis) which is widely distributed in the eastern U.S. E. muris eauclairensis has only been found in Minnesota and Wisconsin.
- Preventing tick bites is the best way to protect yourself from ehrlichiosis.
Signs and Symptoms
What are the signs and symptoms of Ehrlichiosis?
- The signs and symptoms associated with these Ehrlichia species will typically develop 1-2 weeks after the bite from an infected tick.
- The early signs (first 5 days of illness) include:
- Fever, chills
- Severe headache,
- Muscle aches,
- Nausea, vomiting, diarrhea, loss of appetite
- Rash-red splotches or pin-point dots - more common in children (60%) than adults (30%)
- Early treatment with antibiotics can reduce the risk of developing late-stage disease, which can be fatal.
- Risk factors for severe illness include delayed antibiotic treatment, being very young or very old, or having a weakened immune system.
- Late-stage signs include:
- Inflammation of the spinal cord and brain
- Respiratory failure
- Uncontrolled bleeding
- Organ failure
Diagnosis and Testing
How is ehrlichiosis diagnosed?
- Ehrlichiosis is a difficult disease to diagnose.
- The disease symptoms may vary from person to person and may resemble other diseases.
- Diagnostic tests, especially those based on the detection of antibodies, will often appear negative for the first 7-10 days of illness.
- There is no test available at this time that can provide definitive results during the initial stages of the disease.
- If your healthcare provider thinks you have ehrlichiosis or another tickborne infection, they may prescribe antibiotics while you wait for test results.
- The diagnosis must be made based on clinical signs and symptoms, and can later be confirmed with blood tests.
What is the treatment for ehrlichiosis?
- Doxycycline is the first line treatment for adults and children of all ages and should be initiated immediately whenever ehrlichiosis is suspected.
- Infected individuals who are treated early and correctly may recover quickly via outpatient medication.
- However, those experiencing more severe symptoms may require hospitalization.
- Treatment should never be delayed pending the receipt of laboratory results, or be withheld on the basis of an initial negative laboratory result.
Educational Materials and Guidance Documents
- Michigan Tick ID Card - Pocket-sized card for identifying common ticks in Michigan. Information regarding tick removal and tick-bite prevention.
- Michigan's Five Most Common Ticks - Ticks are significant vectors (carriers) of pathogens that cause human and animal disease. In Michigan, tick-borne diseases are rare, but they do occur and can be serious if not properly diagnosed and treated.
- Michigan: Ticks and Your Health - Brochure describing Lyme disease and other tick-borne diseases in Michigan. Other topics covered include tick-bite prevention, preventing ticks on pets, and landscape techniques to minimize tick risk.
Centers for Disease Control and Prevention Resources
- Diagnosis and Management of Tickborne Rickettsial Diseases: Rocky Mountain Spotted Fever and Other Spotted Fever Group Rickettsioses, Ehrlichioses, and Anaplasmosis - A Practical Guide for Health Care and Public Health Professionals
- Tick Removal
- Tickborne Diseases of the U.S. - A Reference Manual for Healthcare Providers
- What To Do After a Tick Bite
- CDC: Healthcare Provider Training Module-Diagnosis and Treatment of Anaplasmosis and Ehrlichiosis with Free Continuing Education Credits
Data and Statistics