Please note: This information was current at the time of publication. But medical information is always changing, and some information given here may be out of date. For regularly updated information on a variety of health topics, please visit, the AAFP patient education website.

Information from Your Family Doctor

What is Babesiosis?


Am Fam Physician. 2001 May 15;63(10):1976.

Babesiosis (say: bab-e-see-oh-sis) is a rare illness that is caused by a parasite, or bug, that lives in some ticks. Deer ticks carry the parasite that causes this illness. Whenever you find a tick on you or on someone else, try to save it to show to your doctor.

A tick must stay attached to your body for at least 24 hours before it can pass on this parasite.

Babesiosis infections have been reported in many parts of the United States. The most common areas are in Connecticut and on the islands off Massachusetts and New York.

What are the symptoms of babesiosis?

Symptoms include fever (as high as 104° F), chills, sweating, weakness, tiredness, poor appetite and headache.

Some persons with the illness may not have symptoms. But sometimes the illness quickly becomes serious and can even cause death. Babesiosis can affect persons 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 do more blood tests to look for other infections that ticks carry.

How is babesiosis treated?

Two antibiotics are usually needed for treatment. If you have babesiosis, you may need to go to a hospital to be treated.

If you develop shortness of breath or any other symptoms after you start taking the antibiotics, tell your doctor right away.

How can I prevent babesiosis?

Stay away from places where ticks are common during the months of May through September. This is very important if you've had your spleen removed, if you have had an organ transplant or if you have HIV infection, AIDS or other problems with 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 N,N-diethyl-m-toluamide, or DEET. Products with 10 to 35 percent DEET will provide good protection under most conditions.

Early removal of ticks is important. 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.

This handout is provided to you by your family doctor and the American Academy of Family Physicians. Other health-related information is available from the AAFP online at

This information provides a general overview and may not apply to everyone. Talk to your family doctor to find out if this information applies to you and to get more information on this subject.


Copyright © 2001 by the American Academy of Family Physicians.
This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. Contact for copyright questions and/or permission requests.

Want to use this article elsewhere? Get Permissions


May 2022

Access the latest issue of American Family Physician

Read the Issue

Email Alerts

Don't miss a single issue. Sign up for the free AFP email table of contents.

Sign Up Now

Navigate this Article