Babesiosis - Fact Sheet


For the most current information about babesiosis, please visit the Centers for Disease Control and Prevention website.

Connecticut Epidemiologist Newsletters

Published articles concerning babesiosis in Connecticut.


Additional Information

What is babesiosis?
Babesiosis is an infection caused by a protozoan (one celled-parasite) called Babesia microti. This parasite invades and lives within red blood cells. Babesiosis is a newly recognized disease that is emerging in areas with high rates of Lyme disease.

How is babesiosis spread?
Babesiosis is transmitted to humans through the bite of a tick. In Connecticut, the tick that transmits babesiosis is Ixodes scapularis (commonly called the deer tick), the same tick that transmits Lyme disease.

Who gets babesiosis?
Although everyone is susceptible to the disease, people who spend time outdoors in tick infested areas are at an increased risk of exposure. The disease is more severe in the elderly and in people who have weakened immune systems, especially those who have had their spleens removed.

What are the symptoms of babesiosis?
Although most people will not become sick if they have babesiosis, some will become sick. The symptoms are mostly nonspecific, and the illness can range from very mild to very severe. Patients who become sick may experience fever, drenching sweats, muscle or joint pain and malaise. A breakdown of the red blood cells, called hemolytic anemia, is also common. Less frequent symptoms may include nausea, vomiting, headache, shaking chills, and skin rash.

How soon do symptoms appear?
Symptoms usually start within 1-4 weeks of the tick bite.

How long can an infected person carry babesiosis?
The number of parasites in the blood is not an indicator of the severity of the disease. People can have parasites in their blood for weeks to months, but the infection can be eliminated with prescription treatment.

How is babesiosis diagnosed?
Babesiosis can be diagnosed by blood tests, either by measuring your body’s immune response to the infection, or by testing for DNA of the parasite. Usually, to get confirmed results, blood needs to be drawn twice, once when you first get sick and again 4-6 weeks later.

What is the treatment for babesiosis?
While many people do not become sick enough with babesiosis to require treatment, there are effective therapies, usually either a combination of quinine and clindamycin or a combination of atovaquone and azithromycin. It is possible to become infected with babesiosis and Lyme disease at the same time, so be sure to seek medical attention if you become ill after a tick bite.

How can babesiosis be prevented?
To prevent babesiosis and other tick-borne infections, the best protection is to avoid contact with ticks. When working or playing outside in areas that ticks inhabit (tall grass and weeds, shrubby areas, woods, and leaf litter) you should:

  • Wear light colored clothing (to spot the ticks easily), long sleeved shirts and long pants.
  • Create a “tick barrier” by tucking pants into socks and shirt into pants.
  • Consider using insect repellent, according to manufacturer’s instructions, when planning to be outdoors.
  • Check clothing and skin very carefully (especially thighs, groin, arms, underarms, legs and scalp) after being outdoors in tick infested areas and remove any ticks promptly.
  • Wash the area with soap and water and apply an antiseptic when the tick has been removed.
  • Keep your lawn mowed, cut overgrown brush, and clear any leaf litter away from the home.
  • Inspect pets daily and remove any ticks found.

How should a tick be removed?

  • It is important that a tick is removed as soon as it is discovered.
  • Remove the tick as soon as possible using tweezers. Grasp the tick mouth parts as close to the skin as possible and pull the tick out with steady pressure. Do not yank the tick out. Do not crush the ticks body as it may contain infectious fluids.
  • Do not use petroleum jelly, hot matches, nail polish remover, or any other substance to remove a tick. By using these substances, you may actually increase your chance of infection.
  • Thoroughly wash the area of the bite with soap and water and put an antiseptic on it.
  • Check after every 2 to 3 hours of outdoor activity for ticks attached to clothing or skin.
  • The sooner the tick is removed, the lesser the risk of tick-borne infection.
  • Write on the calendar the date you removed the tick and the part of the body it was removed from.
  • Contact your physician for recommendations on testing and treatment.



This fact sheet is for informational purposes only. It should not be used for self-diagnosis or as a substitute for consultation with a health care provider. If you think that you may have this infection, or have questions about the disease described above, you should consult your health care provider.







To contact the Epidemiology and Emerging Infections Program, please call 860-509-7994.