Babesiosis is an illness spread by the deer tick, also known as the black-legged tick. It is caused by a parasite called Babesia that infects red blood cells. Ticks that spread babesiosis can be found in every county in Wisconsin. Not all tick bites will make you sick, but it is still important to take steps to protect yourself and your family while enjoying time outdoors. Babesiosis is preventable and treatable.

General information on babesiosis, including information on signs and symptoms, treatment, and resources.

Maps and charts with babesiosis data.


Information for local health departments, health care providers, or those looking for information on reporting, surveillance, or diagnosis of babesiosis.

Tips on preventing tick bites.

Questions about illnesses spread by ticks? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976

Last Revised: February 1, 2022