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What is babesiosis?

  • Babesiosis is a tick-borne disease that is caused by microscopic parasites that infect red blood cells. 
  • There are multiple different species that have been known to infect animals, however, only a few that have been found in humans. 
  • The most common species in people is Babesia microti.
  • Babesia is transmitted by infected Ixodes scapularis ticks (also known as blacklegged ticks or deer ticks). 
  • The blacklegged tick, which is common in the Upper Peninsula and spreading in the Lower Peninsula, may also transmit Lyme disease, anaplasmosis, and ehrlichiosis.
  • Babesiosis is preventable if simple steps are taken to prevent tick bites.


  • Got A TICK? SUBMIT IT FOR ID, Information on identifying and testing ticks

    GOT A TICK? SUBMIT A PIC! Click here for more information on picture ID

    MiTracking, Michigan Environmental Public Health Tracking

    Emerging and Zoonotic Disease Surveillance Summary

    Link to 2021 Michigan Trends in Tickborne Disease Report


    • Everyone is susceptible to babesiosis, but people who spend time outdoors in tick-infested environments are at increased risk of exposure. 
    • Cases of babesiosis mostly occur in parts of the Northeast and upper Midwest and peak during the warm months when ticks are active.
    • Although previously rare in Michigan, locally acquired cases of babesiosis are likely to increase as black-legged tick populations expand in the state.
    • Since the Babesia parasites infect the red blood cells and circulate in the blood stream, these pathogens may pose a risk to be transmitted through blood transfusions.  
    • Babesiosis may also be a risk during organ transplantation. 
    • In addition, there is risk of transmission from an infected mother to her baby during pregnancy or delivery. 
    • Individuals that do not have a spleen, have a weak immune system, have other serious health conditions, and/or are elderly may be at increased risk for developing severe forms of this disease. 



  • What are the signs and symptoms of babesiosis?

    • Babesia infection can range in severity from asymptomatic to life threatening. 
    • If individuals develop symptoms, they typically start within a week or so after the tick bite and may develop within a few weeks or months (or longer). 
    • Many people who are infected do not develop any symptoms.  However, others may develop flu-like symptoms, including fever, chills, sweats, headaches, body aches, loss of appetite, nausea, and/or fatigue. 
    • Since these parasites infect red blood cells, hemolytic anemia may result (from the destruction of red blood cells).  This could cause jaundice (yellowing of the skin) and dark urine. 
    • Babesiosis may be life-threatening especially for those individuals with weakened immune systems, already have serious health conditions, do not have a spleen, and/or are elderly. 
    • Severe cases may be associated with a low and unstable blood pressure, severe hemolytic anemia (hemolysis), very low platelet count (thrombocytopenia), disseminated intravascular coagulation (also known as "DIC" or consumptive coagulopathy which can lead to blood clots and bleeding, malfunction of vital organs (such as the kidneys, lungs, and liver), or death.  



    • In people with symptoms, babesiosis is usually diagnosed by examining blood specimens under a microscope to look for Babesia parasites inside red blood cells.
    • To confirm the diagnosis, your healthcare provider may send specimens to a specialized reference laboratory (such as the Centers for Disease Control and Prevention)



    Can babesiosis be treated?

    • Effective treatment is available for symptomatic people.
    • People who are not exhibiting any signs or symptoms of babesiosis typically do not need to be treated.   
    • Treatment for babesiosis usually involves a combination of two prescription medications prescribed for 7-10 days.
    • If you believe that you or a family member may have babesiosis, please consult with your local healthcare provider.