What Is Anaplasmosis? Here's How Experts Explain This Rare Infection That Mimics Lyme Disease

How to tell the difference, plus when you should seek medical help.

Chances are, if you're spending a lot of time outdoors, you're likely going to encounter a few bumps in the road health-wise: the occasional sunburned shoulder, a poison ivy rash on your ankle, a couple mosquito bites. If you live in—or have plans to visit—a region with lots of hiking trails in wooded areas, you should probably add tick bites to the list of offenders to be aware of and protect against.

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While you likely associate ticks with Lyme disease, that isn't the only health condition that can result from a bite. Tick bites can also cause a less common—but potentially serious—infection called anaplasmosis, which should be treated as soon as you notice symptoms. Below, you'll find info on anaplasmosis symptoms, treatments, and prevention methods.

What is anaplasmosis?

Put simply, it's an illness caused by the bacterium Anaplasma phagocytophilum, per the Centers for Disease Control and Prevention (CDC), which notes that anaplasmosis was previously known as human granulocytic ehrlichiosis (HGE). Blacklegged ticks, which also carry the bacterium that causes Lyme disease, carry Anaplasma phagocytophilum, thus also transmitting anaplasmosis.

The study of anaplasmosis is relatively recent; it was only first recognized as a human disease in the US in the mid-90s, per the CDC. When anaplasmosis became reportable to the CDC in 2000, only 348 new cases were noted. However, that number has steadily grown over the years, hitting a peak of 5,762 new cases in 2017.

While anaplasmosis infections have been reported in various regions of the country, they're most common in the Northeast and northern areas of the Midwest, per the CDC. The tick that carries the bacterium that causes anaplasmosis, the blacklegged tick, is expanding its range (moving into new territories), and, as a result, the geographic range of anaplasmosis cases is also expanding, according to data from the CDC.

What are the symptoms of anaplasmosis?

According to the CDC, the following symptoms of anaplasmosis can occur during the first phase (days one through five) of the illness:

  • Fever
  • Chills
  • Muscle aches
  • Severe headache
  • Vomiting
  • Diarrhea
  • Nausea
  • Loss of appetite

If a patient infected with anaplasmosis doesn't seek help after noticing these symptoms, the illness can progress and cause serious health problems or even death, Purvi Parikh, MD, an infectious disease specialist at NYU Langone, tells Health.

Per the CDC, the following are symptoms of late illness:

  • Respiratory failure
  • Organ failure
  • Bleeding problems
  • Death

Dr. Parikh emphasizes that it's important to get treated promptly if you suspect you've been exposed to ticks and you start experiencing the above symptoms: "It can be dangerous if not treated appropriately."

What's the difference between Lyme disease and anaplasmosis?

Some symptoms of anaplasmosis overlap with those of Lyme disease, Dr. Parikh says. However, there are a few differences. For one thing, Lyme disease patients are less likely to suffer from diarrhea, vomiting, and nausea, which are common symptoms of anaplasmosis, she says. She adds that anaplasmosis might manifest with more respiratory problems than Lyme disease, as well.

Additionally, Lyme disease can cause a rash that looks like a target mark with a red ring encircling the spot where the tick bit, and this isn't so much associated with anaplasmosis, Alan Taege, MD, an infectious disease specialist at Cleveland Clinic, tells Health. "Lyme disease very commonly will have the usual rash or target lesion that's described, [but] anaplasmosis rarely has a rash," Dr. Taege explains.

How is anaplasmosis diagnosed?

Fortunately, there's a definitive way for doctors to know whether they're dealing with anaplasmosis or not. "It is diagnosed by a blood test," Dr. Parikh says, explaining that, after doctors have evaluated all the signs and symptoms, blood tests are used to make 100% sure the patient is suffering from anaplasmosis and not a similar infection.

If you notice a tick on you after a day spent in your garden or on a hike, you might be tempted to keep it in a plastic bag and show it to your doctor if you start experiencing symptoms of infection. While this won't necessarily hurt, Dr. Parikh says, it might not end up doing you any good, since infectious disease specialists might not know what they're looking at when you present them with a tick. "It can be helpful, but I don't know enough about how the ticks look. I would still order the bloodwork [to confirm the diagnosis]," she explains.

How is anaplasmosis treated—and how can you prevent it?

Luckily, the number of people who die as a result of an anaplasmosis infection (technically called the case fatality rate) is low. According to the CDC, less than 1% of individuals who have anaplasmosis die as a result of it in the United States. But, again, it's important to receive treatment early to prevent serious illness or death.

As with other infections, your doctor might suggest antibiotics once they confirm an anaplasmosis infection. "Usually, we treat it with antibiotics. Doxycycline is a common one," Dr. Parikh says. Doxycycline is commonly used to treat bacterial infections, including those spread by not only ticks but also mites, infected animals, lice, and contaminated water and food, per MedlinePlus, a resource from the US National Library of Medicine (USNLM). Patients who take doxycycline usually feel better in no time, Dr. Taege says: "People respond rather quickly. Within 48 hours [they're] feeling better, temperature's going away."

While the drug would likely be prescribed for those in the early stages of anaplasmosis, more serious treatments might be required for those who delay seeing a doctor. You could end up hospitalized in the ICU if you allow the infection to progress, causing those late stage symptoms, such as organ failure, Dr. Parikh warns.

In terms of prevention, there are many ways to keep yourself safe from ticks and tick-borne illnesses like Lyme disease and anaplasmosis in the first place, experts say. Before you even head out for an activity—even if it's just pulling weeds in your garden—pay attention to what you're wearing, Dr. Taege says. "It's ideal to wear lighter-colored clothing. You can see ticks: brown, black, darker-colored," he explains. You should also make sure to tuck your pant legs into your shoes so they don't crawl up to the skin of your legs, he warns. Also, consider applying DEET-containing insect repellent to keep ticks away, Dr. Taege says.

And one of the best ways to protect yourself is to check your body for ticks each time you come in from an outdoor activity, he adds. "Do a careful tick check, head to toe, when you do come in. If you remove it in the first 36 hours, the likelihood of becoming ill from it is very small."

If you do notice a tick, there's a specific way you should go about removing it so you don't cause infection. "Don't do the old wives' tales; don't try to burn them off," Dr. Taege says. "Try to gently clean the area, get fine-nosed tweezers, get close to the skin surface, and pluck it off. Don't squeeze the body."

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