Many people who are infected with Babesia microti feel fine and do not have any symptoms. Some people develop nonspecific flu-like symptoms, such as fever, chills, sweats, headache, body aches, loss of appetite, nausea, or fatigue.

Because Babesia parasites infect and destroy red blood cells, babesiosis can cause a special type of anemia called hemolytic anemia. This type of anemia can lead to jaundice and dark urine.

Babesiosis can be a severe, life-threatening disease, particularly in people who:

• do not have a spleen;
• have a weak immune system for other reasons (such as cancer, lymphoma, or AIDS);
• have other serious health conditions (such as liver or kidney disease); or
• are elderly.

Complications of babesiosis can include:

• a low and unstable blood pressure;
• severe hemolytic anemia (hemolysis);
• a 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.