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This fact sheet answers frequently asked questions about babesiosis.

Babesiosis is a rare, sometimes severe, disease caused by a parasite that infects red blood cells.  

The basics

How does babesiosis spread?

Babesiosis is usually passed to humans through the bite of an infected tick. In Massachusetts this is typically a deer tick. The highest risk of disease occurs between late May and September, when ticks are most active. The tick must attach and feed for about 36-48 hours before it can pass the germ to a person.

Who gets babesiosis?

Anyone can get babesiosis, but people who spend time outdoors are at an increased risk of exposure. Ticks infected with babesiosis most often live in coastal areas, such as Nantucket, Martha's Vineyard, and Cape Cod. The illness can also pass through a transfusion of contaminated blood or from a pregnant woman to her child, but these are very rare.


What are the symptoms of babesiosis?

Most infected people will show very mild signs of illness or no signs at all. For people who do become ill, symptoms can range from mild to severe and can last for several days or weeks. Signs and symptoms include fever, chills, headache, nausea, vomiting, abdominal pain, tiredness, muscle and joint aches, dark urine, and anemia. The disease can be especially serious in persons who are elderly, who do not have a healthy spleen, who have a weakened immune system, or who have other health problems. It is possible to get babesiosis and other diseases spread by ticks (like Lyme disease) at the same time from a single tick bite.

How soon do symptoms appear?

Symptoms usually start within 1 to 6 weeks after the tick bite.


How do I prevent babesiosis?

To prevent babesiosis and other infections spread by ticks, avoid contact with ticks. Follow these tips when working or playing in areas where you may find ticks:

  • Wear light colored clothing (to spot the ticks easily), long sleeved shirts and long pants
  • Exam pets for ticks
  • Create a "tick barrier" by tucking pants into socks and shirts into pants
  • Consider using insect repellents, such as 20 to 30% concentrations of DEET or 0.5% permethrin when planning to be outdoors. Follow the manufacturer's directions on the label. After returning indoors, wash treated skin with soap and warm water
  • There are other insect repellents approved by the EPA for ticks. For more information, visit the EPA
  • Check clothing and skin very carefully (especially thighs, groin, arms, underarms, legs and scalp) after being outdoors in tick infected areas. Remove any ticks promptly using fine point tweezers. To remove the tick, grasp the tick as close to the skin as possible and pull the tick straight out with steady pressure. Once removed, disinfect the area with rubbing alcohol 
  • Talk with your veterinarian about the best way to protect your pet against ticks

Click here to learn more about tickborne diseases.


What is the treatment for babesiosis?

Many people do not become sick enough with babesiosis to need treatment. However, there are medications that are effective in treating the illness. 

Can a person get babesiosis more than once?

It is not known if a person who has had past infection with babesiosis can get it again.

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