ExitCare ImageBabesiosis is an infectious disease caused by a parasite that is carried by ixodid ticks (wood ticks, deer ticks). Infections most commonly occur from May through September when ixodid ticks are active and people are spending more time outdoors. Babesiosis affects both adults and children. Most cases of this illness have occurred in the northeastern United States, Michigan, and Wisconsin. This is an increasingly common illness that shows itself in many different forms. Infected people may have no symptoms, have a flu-like illness, or become more seriously ill.


The Babesia parasite is spread to people from the bite of an infected tick. The parasite then lives in a person's red blood cells. Except by receiving a blood transfusion or transplanted organ from another affected person, this infection cannot be passed to other people. Babesia are carried by different ticks that live and feed on the blood of deer, rabbits, rodents, bats, and some birds. People get bitten when walking through areas where these ticks live. Because ticks are small and their bite is painless, most people who have babesiosis do not recall having a tick bite.


Babesiosis can cause several different forms of illness:

  • An infection with no symptoms.

  • A mild flu-like illness with fever, chills, sweats, fatigue, nausea, vomiting, and muscle and joint aches and pains.

  • A moderately severe form of illness with high fever, headache, chills, and anemia.

  • A sudden, severe and life-threatening illness.

People with certain risk factors are more likely to have more severe illness. These risk factors include:

  • Being over the age of 50.

  • Having a weakened immune system because of a disease or its treatment (cancer, organ transplantation, HIV).


Your caregiver may suspect babesiosis based on your symptoms, your recreational activities, your travel history, or where you live. The diagnosis of babesiosis can be made by examining your blood under a microscope or by a blood test.


Taking a combination of antibiotics is usually effective in treating this illness. Antibiotics are not necessary if you have few or no symptoms, unless your infection has been present for more than 3 months.


Ticks prefer to hide in shady, moist ground. However, they can often be found above the ground clinging to tall grass, brush, shrubs, and low tree branches. They also inhabit lawns and gardens, especially at the edges of woodlands and around old stone walls. Within the normal geographic areas where babesiosis occurs, no vegetated area can be considered completely free of infected ticks. In tick-infested areas, the best precaution against infection is to avoid contact with soil, leaf litter, and vegetation as much as possible. Campers, hikers, field workers, and others who spend time in wooded, brushy, or tall grassy areas can avoid exposure to ticks by using the following precautions:

  • Wear light-colored clothing with a tight weave to spot ticks more easily and prevent contact with the skin.

  • Wear long pants tucked into socks, long sleeve shirts tucked into pants, and enclosed shoes or boots.

  • Use insect repellent. Spray clothes with insect repellent containing either DEET or permethrin. Only DEET can be used on exposed skin. Make sure to follow the manufacturer's directions carefully.

  • Wear a hat and keep long hair pulled back.

  • Stay on cleared, well-worn trails whenever possible.

  • Check yourself and others frequently for the presence of ticks on clothes. If you find one tick, there may be more. Check thoroughly.

  • Remove clothes after leaving tick-infested areas and, if possible, wash them to eliminate any unseen ticks. Check yourself, your children, and any pets from head to toe for the presence of ticks.

  • When attached ticks are found, remove them as soon as possible. Use a tweezer to grab hold of the tick by its mouth parts and pull it off. Ticks often need to be on your body for 2 or more days in order to transfer the illness to you.

  • Shower and shampoo after possible exposure to ticks.


  • Take any medicines or treatments as told. It may take days or weeks to improve.

  • Take your antibiotics as directed. Finish them even if you start to feel better.

  • Be sure you understand any activity restrictions and diet instructions from your caregiver.

  • Report any new symptoms to your caregiver, especially if you have a rash. People who have babesiosis could also have other infections passed to them from the tick bite.


  • You are not improving in the time expected.

  • You develop a rash.

  • You become ill again after initial improvement.


  • You develop sudden, severe weakness.

  • You develop severe abdominal pain.

  • You have difficulty breathing.


  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.