Cases have also been reported in Wisconsin, California, Georgia, and in some European countries. Babesiosis is most commonly spread to people by the bite of a tick infected with the Babesia parasite. Babesiosis is spread by deer ticks, which are carried mainly by deer, meadow voles, and mice. Deer ticks also spread Lyme disease. People can be infected with both babesiosis and Lyme disease at the same time.
People can also get babesiosis from a contaminated blood transfusion.
The parasite attacks the red blood cells. Symptoms, if any, begin with tiredness, loss of appetite, and a general ill feeling. As the infection progresses, these symptoms are followed by fever, drenching sweats, muscle aches, and headache. The symptoms can last from several days to several months. It can take from 1 to 12 months for the first symptoms to appear, but less time for persons with weakened immune systems.