Ehrlichiosis: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Ehrlichiosis?
An infectious disease doctor (a doctor who treats illnesses caused by germs) often treats ehrlichiosis, an illness spread by ticks. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is ehrlichiosis?
Ehrlichiosis is the general name for a group of illnesses caused by bacteria, which are tiny germs. In the United States, three kinds of Ehrlichia bacteria cause it. The bacteria spread to people mainly through the bite of an infected tick. The lone star tick and the blacklegged tick can spread it.
Symptoms
Symptoms usually begin 1 to 2 weeks after the bite of an infected tick. Tick bites can be painless, and many people do not remember being bitten. The first symptoms are usually mild or moderate and may include:
- Fever and chills.
- Severe headache.
- Muscle aches.
- Nausea, vomiting, diarrhea, or loss of appetite.
- Confusion.
- Rash, which is more common in children.
Up to 1 in 3 people with ehrlichiosis report a rash. It can look like red splotches or pinpoint dots. It usually starts about 5 days after the fever begins.
If antibiotic treatment is delayed, ehrlichiosis can sometimes cause severe illness. Severe illness can include damage to the brain or nervous system, respiratory failure, uncontrolled bleeding, organ failure, and death. Respiratory failure means the lungs cannot work well enough.
Causes and who gets it
Most people get ehrlichiosis from the bite of an infected tick. Some people have a higher chance of severe illness.
Delayed antibiotic treatment raises the risk of severe illness. So does being younger than 5, being older than 65, or having a weakened immune system. A weak immune system can come from some cancer treatments, advanced HIV infection, an organ transplant, or certain medicines.
There is no vaccine to prevent ehrlichiosis. People prevent illness by preventing tick bites, ticks on pets, and ticks in the yard.
How doctors diagnose it
Doctors start by asking about your history. They ask about recent tick bites. They ask about time spent in woods or brushy areas with tall grass. They also ask about travel to places where the illness is common. A doctor should not rule out a tick-borne illness just because you do not remember a bite. Ehrlichiosis can be hard to diagnose, especially early in the illness.
Blood tests can find it. A PCR test checks a blood sample for the germ and works best in the first week of illness. A negative PCR result does not rule out ehrlichiosis. Antibody tests look for the body's response to the germ, and they are often negative in the first week of illness. A lab can also look at blood under a microscope for the germ inside white blood cells. This test alone is not reliable enough.
Treatment
Doxycycline, an antibiotic, is the treatment of choice for adults and children of all ages with ehrlichiosis. Early treatment can prevent severe illness. Doctors start treatment as soon as they suspect ehrlichiosis, and they do not wait for test results.
When to see a doctor
See your healthcare provider if you become ill after being bitten by a tick or spending time in grassy, brushy, wooded areas. Do not wait, because delayed antibiotic treatment can sometimes lead to severe illness.
Call 911 or go to the emergency room if you have severe trouble breathing, bleeding that will not stop, or a sudden change in mental state, such as being very confused or hard to wake.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can review your symptoms and tick exposure, order tests, and refer you to an infectious disease doctor when needed.
Common questions
Can ehrlichiosis be treated?
Yes. Doxycycline, an antibiotic, is the treatment of choice for adults and children of all ages. Treatment should start as soon as the illness is suspected, because early treatment can prevent severe illness.
Can you have ehrlichiosis without remembering a tick bite?
Yes. Tick bites can be painless, and many people do not remember being bitten.
Is there a vaccine for ehrlichiosis?
No, there is no vaccine to prevent ehrlichiosis. You can lower your risk by preventing tick bites, ticks on your pets, and ticks in your yard.
Who is at higher risk of severe ehrlichiosis?
Children younger than 5, adults older than 65, and people with weakened immune systems are at higher risk of severe illness. Delayed antibiotic treatment also raises the risk.
Does ehrlichiosis cause a rash?
Sometimes. Up to 1 in 3 people with ehrlichiosis report a rash. A rash is more common in children than in adults.
Sources
- CDC - About Ehrlichiosis
- CDC - Signs and Symptoms of Ehrlichiosis
- CDC - Clinical Testing and Diagnosis for Ehrlichiosis
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
