What is babesiosis?

Babesiosis (say: "bab-e-see-oh-sis") is a rare infection of the blood caused by a parasite that lives in some ticks. Deer ticks typically carry the parasite that causes this illness.

Babesiosis infections are more common in animals than in humans, but cases have been reported in parts of the United States. The areas in which babesiosis has been reported most often are on the coast of Connecticut and New Jersey and on the islands off of Massachusetts and New York.

What are the symptoms of babesiosis?

Symptoms include fever (as high as 104°F), chills, sweating, weakness, tiredness, joint and muscle aches, poor appetite and headache. Some people who have babesiosis may not have any symptoms. However, sometimes the illness can quickly become serious, and can even cause death, especially in people who have had their spleen removed or have weak immune systems. Babesiosis can affect people of all ages, but most people who get it are in their 40s or 50s.

How can my doctor tell if I have babesiosis?

Your doctor will need to do blood tests to see if you have this illness. Your doctor might also do blood tests to look for other infections that ticks can carry.

How is babesiosis treated?

In people who have healthy immune systems and only mild cases of babesiosis, no treatment is typically needed. They body fights the infection on its own. People who have a more severe case of babesiosis are usually treated with two antibiotics. If you develop shortness of breath or any other symptoms after you start taking the antibiotics, tell your doctor right away. Some people who have very severe cases of babesiosis or weak immune systems need to go to a hospital to be treated.

How can I prevent babesiosis?

During the months of May through September, stay away from places where ticks are common. This is especially important if you've had your spleen removed, if you have had an organ transplant, if you have HIV infection, AIDS or other conditions that would weaken your immune system.

You may want to use insect repellent when you are outdoors, especially in wooded or grassy places. One of the best tick repellents is called DEET. Products with 10% to 35% DEET will provide good protection under most conditions.

Early removal of ticks is important. A tick must stay attached to your body for at least 24 hours before it can pass on the parasite that causes babesiosis. If you spend a lot of time outdoors in areas where ticks live, you should check yourself for ticks every day. Check your pets also, because they may carry ticks into your home. Whenever you find a tick on yourself or on someone else, save it so that you can show it to the doctor if symptoms of babesiosis develop.

To remove an attached tick, use fine tweezers to grab the tick firmly by the head or as close to the head as possible and pull. Do not use heat (such as a lit match), petroleum jelly or other methods to try to make the tick "back out" on its own. These are not effective ways to remove a tick.

More Information

For more information talk to your doctor.


Written by editorial staff.

When to Suspect and How to Monitor Babesiosis by E Mylonakis, M.D. (American Family Physician May 15, 2001,

Reviewed/Updated: 07/08
Created: 09/00