Ehrlichiosis and anaplasmosis

Date Updated: 05/05/2026

Overview

Ehrlichiosis (ar-LIK-e-o-sis) and anaplasmosis (ana-plas-MO-sis) are illnesses from tick bites. These illnesses also are called tick-borne illnesses. They cause flu-like symptoms such as fever, muscle aches and headache. Symptoms most often appear within 14 days after a tick bite.

Quick treatment with the right antibiotic can make symptoms better within a few days. If not treated, ehrlichiosis and anaplasmosis can cause serious or life-threatening complications.

The best way to prevent these infections is to not get tick bites. Use a substance to keep ticks away, called tick repellent. Do full-body checks after being outside and remove ticks the right way.

Symptoms

Symptoms of ehrlichiosis and anaplasmosis most often are the same. But symptoms of ehrlichiosis may be worse. Symptoms, which vary from person to person, may include:

Fever.
Chills.
Headache.
Muscle aches.
Not feeling well.
Joint pain.
Upset stomach.
Vomiting.
Loose stools.
Not wanting to eat.

Other symptoms linked with ehrlichiosis but rarely with anaplasmosis include:

Confusion or changes in mental state.
Rash.

Some people may be infected and not get symptoms.

When to see a doctor

If you get any symptoms of illness after a tick bite or after being around ticks, see your healthcare professional. It can take up to 14 days for symptoms to appear.

Causes

Different types of bacteria cause ehrlichiosis and anaplasmosis. The bacterium Ehrlichia chaffeensis causes ehrlichiosis. The Lone Star tick is the main carrier of this bacteria.

The Lone Star tick lives in south-central, southeastern and eastern coastal states. Black-legged ticks, also called deer ticks, are less common carriers.

The bacterium Anaplasma phagocytophilum causes anaplasmosis. Deer ticks carry this bacterium. The ticks live in the Upper Midwest, northeastern states and central Canada. The Western black-legged tick in Western coastal states and other tick species in Europe and Asia also carry it.

Tick bites and infection

Ticks feed on blood. They attach themselves to a host and feed until they swell to many times their size. Ticks can pick up bacteria from a host, such as a deer, and then spread the bacteria to another host, such as a human. The spread of the bacteria from the tick to the host most likely happens about 24 hours after the tick has begun feeding.

Other ways bacteria spread

The bacteria that cause ehrlichiosis or anaplasmosis also can spread through donor blood or organs, from a pregnant person to an unborn baby, also called a fetus, or through contact with an infected animal that's been killed.

Risk factors

The main risk factor for the tick bites that cause ehrlichiosis and anaplasmosis is spending time in grassy, wooded or bushy areas where ticks live. Other factors that increase the risk of a tick bite include:

Being outdoors in warm spring and summer months.
Gardening, camping, hiking, golfing or hunting in grassy areas.
Not wearing clothes that cover all your skin while in areas where there are ticks.
Having a pet that has ticks.

Complications

Without fast treatment, ehrlichiosis and anaplasmosis can have serious effects. People with weakened immune systems are at a higher risk of more-serious and life-threatening complications.

Complications of an infection that isn't treated may include:

Kidney failure.
Lung failure.
Heart failure.
Damage to the central nervous system.
Seizures.
Coma.
Other serious infections.

Prevention

The best way to prevent ehrlichiosis or anaplasmosis is to not get tick bites. If you plan to work or play in an area that is likely to have ticks, follow these tips to protect yourself.

Use substances that keep ticks away, called tick repellents

Spray your outdoor clothing, shoes, tent and other camping gear with a repellent that has 0.5% permethrin. Or buy gear and clothing that has been treated with permethrin.
Use an insect repellent registered with the U.S. Environmental Protection Agency on all exposed skin except your face. Registered repellents include those that have DEET, picaridin, IR3535, oil of lemon eucalyptus, also called OLE, para-menthane-diol, also called PMD, or 2-undecanone.
Do not use products with OLE or PMD on children younger than 3.

Dress for protection

Wear light-colored clothing that makes it easier to see ticks before they bite.
Don't wear open-toed shoes or sandals.
Wear long-sleeved shirts tucked into your pants and long pants tucked into your socks.

Check for ticks

Shower as soon as you can to wash off loose ticks and check for ticks that may have attached.
Use a mirror to check your whole body. Check your underarms, hair and hairline, ears, waist, between your legs, behind your knees, and inside your belly button.
Check your gear. Put your clothes and gear in a hot dryer for at least 10 minutes to kill ticks. Use hot water to wash anything that needs to be washed.

Other tips

Look for ticks every day on pets that spend time outdoors.
Stay on cleared paths as much as you can in wooded and grassy areas.

Diagnosis

Infections from tick bites, such as ehrlichiosis or anaplasmosis, are hard to diagnose based only on symptoms because the symptoms are like those of other common conditions. So tell your healthcare professional about tick bites you've had or if you've been around ticks.

Your healthcare professional also does a physical exam and orders blood tests. You may have more than one test of your blood.

Treatment

Treatment for ehrlichiosis or anaplasmosis is the antibiotic doxycycline (Acticlate, Doryx, others). You may start treatment before your diagnosis is confirmed. Some people with mild symptoms recover without treatment.

You may take the medicine for at least 7 to 10 days. Or you keep taking it for 3 to 5 days after you no longer have a fever and other signs of infection have improved. For more-serious illness, you may need 2 to 3 weeks of antibiotic treatment.

If you're pregnant or allergic to doxycycline, your healthcare professional may prescribe the antibiotic rifampin (Rifadin, Rimactane).

Lifestyle and home remedies

If you find a tick on your body, remove it as quickly as you can. Use the following steps:

Don't try to force the tick out. Don't put petroleum jelly, nail polish, rubbing alcohol or a hot match on the tick.
Use tweezers. Use fine-tipped tweezers to grab the tick firmly near its head or mouth and as close to the skin as you can get.
Remove the tick. Pull the tick's body away from your skin steadily and slowly without jerking or twisting it. If parts of the mouth remain, remove them with clean tweezers.
Kill the tick. Put it in alcohol. Do not crush the tick. Flush the dead tick or wrap tape around it before throwing it in the trash.
Clean up. Use soap and water, rubbing alcohol or hand sanitizer to clean your hands after handling the tick. Clean around the tick bite.

Watch the bite site

A small bump often appears at the site of the tick bite. It looks like the bump of a mosquito bite. It most often goes away in a few days. But if it bothers you or you have symptoms that may mean an infection, call your healthcare professional.

Preparing for an appointment

You may first see your main healthcare professional. Or you may go to an emergency room if your symptoms are bad. Then you may be sent to a doctor who specializes in infectious diseases.

If you think you might have an infection caused by a tick bite, tell your healthcare professional when and where you might have been bitten. If you removed a tick and kept it, bring it to the appointment.

Make a list of:

Your symptoms and when they began.
All medicines, vitamins and supplements you take, including dosages.
Any allergies you have to medicines or anything else.