Ehrlichiosis (air-lik-e-O-sis) is an infectious disease caused by various strains of Ehrlichia (air-LIH-kee-uh) bacteria, transmitted to humans by ticks.


for searching the Internet and other reference sources

Arthropod-borne infections

Ehrlichla sennetsu

Lyme disease

Rickettsial infections

Sennetsu fever

Tick-borne infections

Caused by an organism once thought to infect only dogs, sheep, cattle, goats, and horses, ehrlichiosis was first discovered in humans in 1953 when researchers in Japan found that Sennetsu fever, an illness that resembles mononucleosis * , was caused by Ehrlichia sennetsu bacteria. Since the 1980s, scientists have identified three additional strains * of Ehrlichia bacteria that cause forms of human ehrlichiosis in the United States: E. chaffeensis, which causes human monocytic ehrlichiosis (HME); bacteria similar or identical to E. phagocytophila or E. equi (known to cause ehrlichiosis in animals), which cause human granulocytic ehrlichiosis (HGE); and E ewingii, which has only been seen in a few patients in the midwestern United States and Tennessee.

What Is Ehrlichiosis?

Ehrlichiosis interferes with the body's immune system by attacking white blood cells, a vital part of the body's defense against invading bacteria, viruses, and other microbes * or harmful substances. Untreated, the disease can leave people vulnerable to other infections.

Ehrlichiosis does not spread from person to person. The Ehrlichia bacteria that cause the disease are spread through tick bites. The species that most commonly spread the disease are the lone star tick, the blacklegged tick, and the western black-legged tick.

Between 1986 and 1997, 1,223 cases of human ehrlichiosis were reported in the United States. Most occurred along the Atlantic Coast and in southern and central states, although cases were reported in almost every region of the country. The number of cases peaks during tick season, which runs from April to October.

What Happens When People Get Ehrlichiosis?

Most cases of ehrlichiosis are associated with mild flulike symptoms, such as fever, chills, headaches, muscle or joint pain, nausea and vomiting, cough, stomach pain, and sore throat. Some people with the infection show no symptoms at all. Symptoms usually start within 2 weeks of a tick bite but can take up to a month to appear.

* mononucleosis (mah-no-nu-klee-O-sis) is an infectious illness caused by a virus that often leads to fever, sore throat, swollen glands, and tiredness.

* strains are subtypes of particular species of organisms, such as viruses or bacteria.

* microbes (MY-krobes) are microscopic living organisms, especially bacteria and viruses.

* Lyme (LIME) disease is a bacterial infection that is spread to humans by the bite of an infected tick. It begins with a distinctive rash and/or flulike symptoms and, in some cases, can progress to a more serious disease with complications affecting other body organs.

* antibodies (AN-tih-bah-deez) are protein molecules produced by the body's immune system to help fight specific infections caused by microorganisms, such as bacteria and viruses.

Because ehrlichiosis shares many symptoms with Lyme disease * and other infections transmitted by ticks, diagnosis based on symptoms alone can be difficult. Blood tests are done to look for evidence of Ehrlichia infection, such as antibodies * to the bacteria or the presence of the germ itself in the blood.

If treated early, ehrlichiosis responds very well to certain antibiotics. Over-the-counter medicine such as acetaminophen (uh-see-teh-MIH-noh-fen) can help lower fever and relieve pain. Usually, people recover from mild cases of ehrlichiosis soon after finishing a week of antibiotic treatment. In severe cases, patients may need treatment in the hospital.

Although many cases of ehrlichiosis are mild, the infection can become serious if it is not treated. Some people who get ehrlichiosis develop anemia * and inflammation of the liver and kidneys. Breathing problems, internal bleeding, brain inflammation (encephalitis, en-seh-fuh-LYE-tis), and seizures * can also develop. People with weakened immune systems, such as those with HIV (human immunodeficiency virus * ) infection, certain types of cancer, or the elderly, tend to develop more severe symptoms and complications. For these people, ehrlichiosis can be fatal.

Can Ehrlichiosis Be Prevented?

Avoiding direct contact with ticks is the best way to prevent ehrlichiosis. Experts recommend that people use tick repellent and wear light-colored, long-sleeved shirts (to help find ticks more easily) and long pants tucked into socks when entering potentially tick-infested areas such as woods or campgrounds. After visiting such areas, it is wise to carefully check the body, clothes, and hair for ticks. Pets need to be checked as well.

* anemia (uh-NEE-me-uh) is a blood condition in which there is a decreased amount of oxygen-carrying hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.

* seizures (SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.

* human immunodeficiency (HYOO-mun ih-myoo-no-dih-FIH-shen-see) virus, or HIV, is the virus that causes AIDS (acquired immunodeficiency syndrome), an infection that severely weakens the immune system.



Lyme Disease Foundation, Inc., One Financial Plaza, 18th Floor, Hartford, CT 06103. The Lyme Disease Foundation offers information on tick-borne illnesses and avoiding tick bites on its website.
Telephone 860-525-2000

National Center for Infectious Diseases, U.S. Centers for Disease Control and Prevention, Mailstop C-14, 1600 Clifton Road, Atlanta, GA 30333. The website for this government agency provides information about ehrlichiosis.
Telephone 800-311-3435

User Contributions:

Report this comment as inappropriate
Aug 11, 2013 @ 1:13 pm
Part 1:
I was deathly ill in 2012. I had to quit my job for the "simple flu". I was unable to walk, or comprehend normal everyday life situations. As the "Flu" got worse, doctors began thinking I was just a mental ill case, with fevers. I was diagnosed with Bipolar, Schizophrenia, depression, I was tested for drugs and alcohol. To me, I was scared, embarrassed and SCARED! I'm a mother of 4, and felt like the movie Gothica, where Hollie Berry didn't know what was going on, that was me. I was stripped of my clothes, personal belongings I went to the ER with and placed into a glass room. I was untold of what to expect and why I was like this when I went to the ER with headaches, the Flu and unable to coordinate myself to walk normal. My heart rate was 170-210, this is why they thought I was on a drug. Even after everything I've told them, and the tests coming back negative for everything, I was released. Scared to see doctors, I researched the internet based on my symptoms, for 7 months. When the breathlessness and confusion, unable to swallow began happening, I had to find a doctor. On my 40th doctor, I found one willing to give me help. He started with a MRI (not the best feeling when you're already not feeling well and getting injected with dye and being trapped and unable to breath! But I get through the 30 minutes and came back normal. Then we tried Zoloft thinking it was only anxiety (I was willing to get any help at this point). After my hysterectomy on March 28th, 2012 and giving IV antibiotics, then sent home, horrible things began to happen. I felt every pain in my body, like a spiraling feeling within my bones, the knuckles of my hands and fingers were bright red, and burning hot. I've never had a reaction to antibiotics before. So once again, I was researching on the internet and came along Lyme Hyrxing and tick born infections. I went through this 4 days because my doctors office was closed and I was not going back to the ER. I slowly felt life slipping away, three times to be exact and I'm not sure how I got through those 4 days, but I did. No sleep and just waiting for Tuesday to come, April 4th, I DEMANDED to get tested for Lyme. Not only did I get tested for Lyme, but he tested me for Ehrlichia (something I didn't know what it was at the time. Wish I had more testing done!! then those two!!)
On April 9th, 2012 the tests came back, Lyme was negative (of course) but Ehrlichia was positive. I cried on the phone of joy, thanking him. I wasn't crazy! Something was wrong and I knew it. IT's a feeling I never want to go through again!!

I was then referred to a Infectious Disease Specialist which was stupid. This guy didn't care about how I was felt at all when I was sick, my symptoms, never retested me those -6 weeks like my doctor wanted him too, so I stopped going to him after the 3rd time. It's been just over a year, I was on Doxy for 21 days, but I believe the bacteria went to my brain and I'm slowly recovering from the affects. My vision is horrible now, my current prescription glasses don't help and I have no money for new ones. I still get headaches, but not the migraine type where I was vomiting. I was never retested or tested for other infections and wonder if there's something else there. I wonder this often when I get little episodes of breathlessness, forgetfulness and pain in my joints.
Christine e. Gocuan
Report this comment as inappropriate
Aug 12, 2013 @ 3:15 pm
I am from the Philippines. There has been no known case of erlichia in human here. I have been ill for several years now due to renal failure . My daughter who is only 18yrs old is suffering from arthritis of auto-immune cause which is same as mine.Several years ago, several dogs of mine tested high positive on erlichia canis. Sad to say at that time we had infestation of ticks in our house and it is likely that we've been bitten by such because our dogs do get on our bed. It is just now that I realized that there is a possibility of us getting such disease. I have been to our hospital lab here and they do not have the test for human erlichia. I would like to have myself tested. I have a trip to the U.S.A. This coming October and would like to get details on how I can have myself tested. This is really important for me to find out for myself and if in case I did turn positive, it would also be a big thing for us here in the Philippines that there could be cases of human erlichia already present.
Report this comment as inappropriate
Feb 15, 2014 @ 3:15 pm
You can see I grasp at straws but why not at this point. Did Howard 's short term memory start at very beginning or later?
In all blood work would this test have been given?
After reading this anyone's imiagiation would run away with them.

Comment about this article, ask questions, or add new information about this topic:


Ehrlichiosis forum