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Babesiosis is an illness spread by the deer tick. The deer tick is also known as the black-legged tick. Ticks that spread babesiosis can be found in every county in Wisconsin. Babesiosis is caused by a parasite called Babesia that infects red blood cells.

Not all tick bites will make you sick, but it’s important to protect yourself and your family while enjoying time outdoors.

Babesiosis is preventable. Learn about treatment from the CDC (Centers for Disease Control and Prevention).

Learn more about babesiosis, including signs and symptoms, treatment, and resources.

Maps and charts with babesiosis data.


Local health departments and health care providers can learn about disease reporting, testing, treatment, and more.

Tips to prevent tick bites.


Learn more about babesiosis from the CDC

Contact us

Questions about illnesses spread by ticks? We’re here to help.

Bureau of Communicable Diseases
Phone: 608-267-9003
Fax: 608-261-4976

Last revised January 3, 2023