Babesiosis is an illness spread by ticks. Babesiosis is caused by a tiny parasite called Babesia that infects and destroys red blood cells. The Babesia parasite is spread by the deer tick, also known as the black-legged tick.
Babesiosis is most common in the Northeastern U.S. (especially parts of New England, New York, and New Jersey) and upper Midwest (especially Wisconsin and Minnesota) and peaks during the warm months when ticks are most active. Anyone can get babesiosis, but it is more severe in the elderly and in those who have a weakened immune system.
People who spend more time outdoors are at higher risk of being bitten by an infected tick. Ticks can be found in areas with woods, brush, or tall grass. In Wisconsin, ticks are most active from May to September, but it is important to use caution year-round to prevent tick bites.
Babesia is spread to humans through the bite of an infected deer tick.
- A tick must be attached for at least 36-48 hours to spread the parasite to a person. It is important to remove ticks as soon as they are found to help prevent illness.
- Most humans are infected by immature ticks, called nymphs.
- Nymphs are very small, about the size of a poppy seed. They are difficult to see, and most people may not feel their bite.
- Nymphs are most active during the spring and early summer.
- Adult ticks also spread Babesia.
- Adults are much larger than nymphs, and are more likely to be found and removed before the parasite is spread to the person.
- Adult ticks are most active during the cooler months.
- Ticks can attach to any part of the body but are often found in hard-to-see areas, such as:
- Behind the knees
- In and around the ears
- Inside the belly button
- Although it is rare, a person can also get babesiosis from infected blood products used in transfusions. To help prevent this from happening, potential blood donors who have ever been diagnosed with babesiosis are unable to donate blood.
Babesiosis is preventable and treatable. Visit our Tick Bite Prevention page to learn how to prevent tick bites, and how to properly remove a tick if you are bitten.
Symptoms can show up one to four weeks after being bitten by an infected tick.
It is possible to not have any symptoms and have babesiosis. People who are elderly, have a weak immune system, do not have a spleen, or have other serious health conditions can have more severe symptoms.
Common signs and symptoms include:
- Flu-like symptoms (fever, chills, headache, body aches, loss of appetite, nausea, tiredness)
- Anemia (not having enough red blood cells)
- Low blood platelets (blood cannot clot properly)
- Jaundice (liver complications)
- Spleen and liver enlargement
- Difficulty breathing
- Heart attack
- Kidney failure
- Liver disease
People who do not have symptoms do not need to be treated. Antibiotics used together with certain drugs that treat malaria have been found to work well in most patients. Very severe cases may require a blood transfusion.
- Babesiosis Fact Sheet, P-42028 (Multiple Languages): Educational fact sheet for the general public on babesiosis covering signs and symptoms, treatment, and prevention.
- Tickborne Diseases Risk in Wisconsin, P-01751 (PDF): Educational flyer describing the risk posed by illnesses spread by ticks in Wisconsin.
- Tick Safety Guide Tri-Fold Card, P-01434 (PDF): Educational tri-fold card covering ticks in Wisconsin, proper tick removal, and tick bite prevention.
- Protecting Your Family From Mosquitoes and Ticks, P-02080 (PDF): A fact sheet with simple steps you can take to protect yourself from ticks.
Centers for Disease Control and Prevention (CDC) Resources
- Babesiosis and the U.S. Blood Supply: Information on babesiosis transmission by blood transfusion.
- Preventing Ticks on Your Pets: Information on ticks and your pets.
- It's Open Season on Ticks: A fact sheet on tick bite prevention for hunters.
- CDC Trail Sign: Plastic trail sign used to remind hikers that there are ticks in the area and how to prevent bites. Available for order from CDC.
- Lyme Disease Prevention and Tick Removal Bookmark: A bookmark with information on how to properly remove a tick. Available for order from CDC.
- Don't Let a Tick Make You Sick Comic: An educational comic for kids about preventing illnesses spread by ticks.
- Don't Let a Tick Make You Sick Crossword: An educational crossword for kids about preventing illnesses spread by ticks.
- Wisconsin Ticks and Tick-borne Diseases: Information on ticks and diseases they spread from our partners at the University of Wisconsin-Madison Medical Entomology Laboratory.
- Midwest Center of Excellence for Vector-borne Disease Ticks: Information on ticks found in the Midwest, tick surveillance resources, and tick biology and development.
Babesiosis is preventable and treatable. Visit our Tick Bite Prevention page to learn how to protect yourself from illnesses spread by ticks.
Questions about illnesses spread by ticks? Contact us!
Phone: 608-267-9003 | Fax: 608-261-4976