Babesiosis

Babesiosis is an illness you get from Babesia parasites. You can get it through the bite of infected blacklegged ticks.

Babesiosis (pronounced “buh-BEE-zee-oh-sis”) usually causes flu-like symptoms. But it can lead to life-threatening complications, especially if you’re older than 60 or have a weakened immune system. You’re at particularly high risk for severe disease if you don’t have a spleen. The most common complication is hemolytic anemia, a condition where your red blood cells are destroyed faster than you can make new ones.

Babesiosis is rare. But the number of cases has increased in recent years.

It’s most common in the spring and summer, when young ticks (nymphs) come out. Nymphs are hard to see, even when they’re biting you. Adult ticks also spread babesiosis, but they’re easier to see. You're more likely to remove them before they bite you.

Where can you get babesiosis?

You can get babesiosis in places where Babesia parasites and the ticks that carry them are found together. These areas are in the U.S., Europe and Asia. In the U.S., babesiosis is most common in the Upper Midwest and Northeast, with a few cases on the West Coast.

Symptoms of babesiosis

If you have symptoms, they can start one to four weeks after a tick bite and come on gradually over time. They include:

• High fever
• Tiredness (fatigue)
• Chills
• Sweating
• Headache
• Muscle or joint aches
• Loss of appetite
• Cough

Severe babesiosis may cause additional symptoms, including:

• Yellowish skin or eyes (jaundice)
• Pale skin
• Dark pee (urine)
• Shortness of breath
• Nausea and vomiting
• Abdominal pain
• Neck stiffness
• Sudden mood changes or extreme emotional reactions (emotional lability or PBA)

Some people have no symptoms.

Babesiosis causes

Several types of Babesia parasites cause babesiosis. Babesia microti (B. microti) is the most common cause of symptomatic babesiosis in the U.S. Babesia are protozoa, one-celled organisms that are too small to see without a microscope. They get into your blood through a tick bite. There, they infect and destroy your red blood cells.

In mild cases, this can make you tired. In severe cases, it can be life-threatening.

How do you get babesiosis?

Babesiosis spreads from animals to humans when a tick bites an infected animal — usually a small rodent, like a mouse — and then bites you.

In the U.S., blacklegged ticks (Ixodes scapularis) are the most common carrier of Babesia. Blacklegged ticks are often called “deer ticks,” though deer usually don’t carry babesiosis. In Europe, castor bean ticks (I. ricinus) transmit Babesia.

You can also get babesiosis from a blood transfusion. This happens when a blood donor is infected without knowing it. Rarely, Babesia is transmitted from a pregnant woman to the fetus.

Risk factors

While anyone can get babesiosis, you’re at higher risk for getting severely ill if you:

• Have a compromised immune system due to HIV, cancer, an immune system disorder or immunosuppressive medications
• Don’t have a spleen or your spleen doesn’t work properly
• Are older than 60

Complications

Babesiosis can cause life-threatening complications, especially if you have a weakened immune system. They include:

• Hemolytic anemia
• Enlarged spleen (splenomegaly) or liver (hepatomegaly)
• Fluid buildup in your lungs (pulmonary edema)
• Disseminated intravascular coagulation (DIC) and uncontrollable bleeding
• Organ damage and failure, including respiratory, heart, kidney and liver failure

How doctors diagnose babesiosis

Healthcare providers use blood tests to diagnose babesiosis. First, your provider will examine you and ask about your symptoms and health history. Let them know if you’ve recently (within the past three weeks) been in an area where you could’ve been bitten by a tick, even if you don’t remember being bitten. This could be an area with long grass or wooded areas. It’s also important for your provider to know if you’ve had a blood transfusion in the past six months.

If your provider thinks you could have babesiosis, they’ll order tests to look for parasites in your blood. They’ll also rule out other illnesses that can cause similar symptoms.

How is babesiosis treated?

Healthcare providers treat babesiosis with a combination of medications. These could include:

• Atovaquone
• Azithromycin
• Clindamycin
• Quinine

You might receive them through an IV in your arm or as pills or liquid that you swallow. If you have mild illness and don’t have a weakened immune system, your provider might hold off on medication to see if it gets better on its own.

If you’re very sick, you may need other procedures to get better. These could include:

• Blood transfusion: If you have too few red blood cells, your provider might give you blood from a donor to increase the number.
• Exchange transfusion: If you have a high number of parasites in your blood, your provider may give you an exchange transfusion. This process slowly removes some of your blood and replaces it with donor blood.
• Mechanical ventilation: If you can’t breathe well enough on your own, your provider will put you on a ventilator to help you breathe.
• Dialysis: Dialysis performs your kidneys’ functions if they aren’t working properly.

When should I see my healthcare provider?

See a healthcare provider if you have symptoms of babesiosis, especially if a tick could’ve bitten you. If you have a weakened immune system, seek medical attention right away if you have any signs of infection.

Go to the nearest emergency room if you have signs of serious illness, including:

• Fever over 103 degrees Fahrenheit (39.4 degrees Celsius)
• Severe shortness of breath
• Yellow skin or eyes
• Confusion or other mental changes
• Severe belly (abdominal) pain

What can I expect if I have babesiosis?

What to expect if you’ve been diagnosed with babesiosis depends on your specific situation:

• If you don’t have a weakened immune system and have a mild case of babesiosis, it can go away on its own. Your provider may wait and see if you get better without treatment.
• If you’re at higher risk for severe illness, your provider will treat you with medication.
• If you’re severely ill, your provider will admit you to the hospital. There, they’ll treat the Babesia infection and any complications. You’ll need frequent blood tests to see how you’re responding to treatments.

Sometimes, symptoms can get better but come back later (relapse). If this happens, your provider will have to treat you again. You’re most at risk for relapse if you have a weakened immune system.

How long does it last?

If you don’t have a weakened immune system, babesiosis can go away on its own in one to two weeks. If your provider treats you with medication, you might start to feel better in a day or two.

Even after your other symptoms have gone away, you may still feel tired for several months. You should recover fully once your red blood cell counts return to normal. Ask your provider how long it might take to feel better.

If you have a weakened immune system, babesiosis can last a long time — months or years.

Can it be cured?

Yes, most people with babesiosis make a full recovery. With treatment, it’s very rare to die from it.

Can this be prevented?

Avoiding tick bites is the best way to prevent babesiosis. Cover as much exposed skin as possible and use bug spray when you’re outside during warmer months. Check your skin after being outside and follow directions for safely removing a tick if you find one on you.