Bacterial illness
Anaplasmosis: What It Is, How It Spreads, and How It's Treated
Anaplasmosis is a bacterial illness spread to people by the bite of an infected blacklegged (deer) tick. It most often causes flu-like symptoms such as fever, chills, headache, and muscle aches. It responds well to a common antibiotic, doxycycline, when treated early. It is most often reported in the Northeast and upper Midwest of the US, with fewer cases on the West Coast. It is not spread by the Lone Star tick.
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What it is
Anaplasmosis is an infection caused by the bacterium Anaplasma phagocytophilum. It is closely related to ehrlichiosis, another tick-borne disease, and acts in a similar way. In the US, the blacklegged tick (Ixodes scapularis) carries it in the eastern half of the country. Less often, the western blacklegged tick (Ixodes pacificus) carries it along the West Coast. These same ticks can spread Lyme disease and babesiosis, so people sometimes get more than one infection at once. In rare cases, it has also spread through blood transfusion. Most people recover fully, and the odds are best when it is found and treated quickly. This page is for general learning and is not medical advice.
Symptoms
- Fever and chills
- Severe headache
- Muscle aches (myalgia)
- Feeling unwell (malaise) and tiredness
- Nausea, vomiting, or diarrhea
- Loss of appetite
- Cough (less common)
- Lab results a doctor may see: low white blood cell count (leukopenia) and low platelets (thrombocytopenia). Liver enzymes may be mildly high
How soon symptoms appear
Symptoms usually begin about 5–14 days (roughly 1–2 weeks) after the bite of an infected tick. Many people do not remember being bitten.
Diagnosis
Doctors diagnose it based on your symptoms, possible contact with ticks, and where you live or have traveled, along with blood tests. Routine blood work may show low white blood cell and platelet counts and high liver enzymes. These can be early clues. Antibody tests that confirm it may take days to weeks to turn positive. So doctors tend to start treatment when they suspect it, without waiting for lab results. A rash is not typical of anaplasmosis. If there is a rash, a doctor may check for a second tick-borne illness at the same time, such as Lyme disease.
Treatment
Doxycycline is the antibiotic doctors recommend for adults and children of all ages. CDC notes it works best when started early. Early treatment can prevent severe illness. So doctors usually start it as soon as they suspect the illness, without waiting for test results. Other drugs work less well. Most people improve within a day or two of starting the right drug. Make any decision about medicine with a doctor.
Prevention
There is no vaccine, so the focus is on avoiding tick bites. Use EPA-registered insect repellents, such as those with DEET or picaridin. Treat clothing and gear with permethrin. Stick to the center of trails to avoid brushy, wooded areas where ticks wait. After being outdoors, check your whole body for ticks and shower within about two hours. Tumble dry clothes on high heat for at least 10 minutes to kill any ticks. Check pets often and ask a vet about tick control. Removing ticks quickly and carefully lowers the chance that a bite leads to illness.
Where it occurs
It is most often reported in the Northeast and upper Midwest, which matches the blacklegged tick's range. A smaller number of cases occur along the West Coast, where the western blacklegged tick spreads it. Most infections are caught in late spring and summer, with a peak around June and July. It is not a disease of the Lone Star tick's main range in the Southeast and South-Central states.
When to seek care
Contact a doctor if you get a fever, chills, headache, or muscle aches within a few weeks of a tick bite or time in tick habitat. Do this even if you never saw a tick. Tell the doctor if you may have been around ticks, since early treatment works best. Get care right away for warning signs such as trouble breathing, confusion, unusual bruising or bleeding, or symptoms that get worse fast. This page is for learning. It does not replace care from a doctor. For emergencies such as trouble breathing or anaphylaxis, call emergency services.
Common questions
Does the Lone Star tick cause anaplasmosis?
No. Blacklegged (deer) ticks spread anaplasmosis in the East, and western blacklegged ticks spread it on the West Coast. The Lone Star tick is not a known carrier. Instead, it is linked to ehrlichiosis, STARI, Heartland and Bourbon viruses, tularemia, and alpha-gal syndrome.
How soon do symptoms appear after a tick bite?
Usually about 5–14 days (roughly 1–2 weeks) later. Many people never notice the bite. If you get flu-like symptoms after time around ticks, tell your doctor.
Is anaplasmosis the same as ehrlichiosis?
No, but they are close relatives. Both are bacterial diseases spread by ticks. They cause similar symptoms and are treated with the same antibiotic. But different germs cause them, and different ticks carry them. Anaplasma germs cause anaplasmosis and spread through blacklegged ticks. Ehrlichia germs cause ehrlichiosis and often spread through the Lone Star tick.
How serious is anaplasmosis?
Usually mild to moderate. Most cases respond well to early treatment. Severe illness can happen, including breathing, bleeding, or organ problems. This is more likely when treatment is delayed, or in people with weakened immune systems. That is why fast care matters.
Is there a vaccine for anaplasmosis?
No. There is no vaccine, so preventing tick bites is the best protection. Use repellent, treat clothing with permethrin, and check for ticks after being outdoors.
Sources
- 1.Anaplasmosis (opens in a new tab) · CDC
Spread by blacklegged and western blacklegged ticks; treatable with prompt antibiotics.
- 2.
- 3.Lyme Disease (opens in a new tab) · CDC
Spread by blacklegged (deer) ticks, NOT the Lone Star tick. Early sign is often an expanding erythema migrans rash.
This page is here to help you learn. It is not medical advice. Only a doctor can diagnose a tick-borne illness. Read our sources and disclaimer.