Babesiosis is an illness caused by a parasite of the Babesia spp., which infects and destroys the red blood cells. The disease is transmitted mainly by ticks which become infected by feeding on infected cattle, roe deer and rodents, which are the main reservoirs for this parasite.

While most infections pass by without symptoms, some people may become sick and present with flu-like symptoms like fever, chills, muscle ache, fatigue, as well as jaundice (yellowing of the skin due to a bile disorder). Severe cases, affecting the kidneys or the lungs, may occur and lead to death.

Human babesiosis infection is treated with antibiotics and quinine. There is no vaccine available.