What is it?

Anaplasmosis is a bacterial disease transmitted by a tick.  


The disease is spread by a bite by the same tick that spreads Lyme disease - Ixodes scapularis, also known as the deer tick or blacklegged tick. The tick - and hence both Lyme disease and Anaplasmosis - are found in the Northeast or the Upper Midwest in the US. The disease has also been tied in some cases to the western blacklegged tick (Ixodes pacificus) along the Pacific coast.

Usually most ticks do not have the bacteria. Even those that have the bacteria don't always transmit it. The tick bite has to last at least 12-24 hoursMost who are bit don't get sick (only 1 in 31 in one study).

Infection if it does occur usually begins 1-2 weeks after the bite.

What are the symptoms?

Patients may have fever, chills, muscle ache, headache, tiredness, nausea/abdominal pain, cough, confusion - and rarely, a rash.

For many it can cause a mild seemingly "viral" infection.

Co-infections can occur with the other infections spread by the same tick (Lyme Disease and Babesia) in as many as 10%.

Anything unusual?

Anaplasmosis hides in white blood cells. It can be seen under a microscope in white cells.

It is a rickettsial bacteria, which is a genus that also includes Rocky Mountain Spotted Fever, a very serious infection.

How bad is it?

Many recovery quickly. Many can be treated with outpatient treatment.

About 3% develop life-threatening symptoms.

Mortality is about 1%. Those who become very sick have problems breathing, kidney problems, breathing, or neurologic problems. They may require an intensive care unit.

Those who become sick may have received no antibiotic or an inappropriate antibiotic. (The disease is almost always best treated by doxycycline).

Where is it found?

Anaplasmosis is found where the ticks that transmit it are. The deer tick is found in the Northeastern or the Upper Midwestern US. The less common vector, the western blacklegged tick, is found on the Pacific West Coast.

The states where the most cases are found are: Minnesota, Wisconsin, and Rhode Island (with 97, 79, and 51 cases over a 4 year period).

In some parts of the US, it is the second most common tick borne illness after Lyme disease.

It is also found in parts of China, Korea, Russia and parts of Europe.

Who is most at risk?

The infection is usually associated with outdoor activities or anything that would expose someone to ticks.

Those who are immunosuppressed are at the most risk. This includes those who have no spleen, have HIV, certain cancer treatments, or are on steroids or medications after an organ transplant.

Also at risk are those who receive blood transfusions. The bacteria hides in white blood cells and has been transmitted through transfusions. It can last for one week in refrigerated blood.

Leukoreduced blood can still have some infected white blood cells. Infections have occurred with donors have been newly infected or have no symptoms.

Because the bacteria is in the blood, there are animal infections due to blood borne exposures in animals - such as from reused needles in cattle.

How common is it?

In 2010, there were a little over 1760 cases diagnosed. This is about 6.1 cases per 1 million a year.

The disease is being diagnosed more and more - but it's also a disease that is becoming more and more recognized.

Why haven't I heard of this?

Anaplasmosis wasn't recognized as a disease affecting us until the mid 1990s. Until 2001, the disease was called the human granulocytic ehrlichiosis (HGE) (which is different from ehrlichiosis or human monocytic ehrlichiosis). However, the bacteria name changed in 2001 to Anaplasma and the disease name soon changed.

How is it treated?

Talk to your healthcare provider about treatment.

Doxycycline is the treatment. This antibiotic, also called doxy, can be given as a pill or IV.

This is true for children as well, per the CDC and the AAP.

Treatment earlier has better outcomes. Treatment with a drug other than doxycycline has been associated with worse outcomes

If a patient is treated in first 5 days of disease, the fever should go away in 1-3 days. No response to doxy brings into question the diagnosis of anaplasmosis.

There is no vaccine.

How is it diagnosed?

Lab tests can confirm a diagnosis, usually through PCR testing. It can be seen inside of white blood cells under a microscope.Testing can be done at the CDC with the help of state and local labs.This can be important if there is a question that the diagnosis might be RMSF, Rocky Mountain Spotted Fever, which can be more dangerous.

Can my dog get sick?

Yes. It can affect dogs, cows, and cats (though little is known about infections in cats).

How to avoid ticks:

Avoid areas with high grasses, bushes, and wooded areas

When in these potential tick areas:

  • Use insect repellent with DEET
  • Wear clothing with long sleeves and pants; pull socks over pant legs
  • Use permethrin on clothing

Immediately after visiting tick areas:

  • Do a full-body tick check – especially through bathing/showering
  • Check pets and any gear for ticks

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