Babesia Cases Skyrocket in Wisconsin with 26-Fold Increase
Babesia cases Wisconsin have increased significantly over time, with reports showing both rising incidence and geographic expansion.
Between 2001 and 2015, Babesia cases in Wisconsin increased 26-fold. “There was a 26-fold increase in the incidence of confirmed babesiosis, in addition to geographic expansion,” according to MMWR.
Factors such as suburbanization, forest fragmentation, and warming temperatures have been proposed as contributors to this trend.
The rise in coinfections in rodents may also play a role. Studies have shown that rodents frequently carry multiple tick-borne pathogens, increasing transmission risk.
In the Northeastern U.S., Diuk-Wasser and colleagues found that co-infection prevalence in rodents ranged from 6% to 41%, with overlapping infection by B. burgdorferi and B. microti in ticks.
Babesia Cases in Wisconsin Can Be Severe
Babesia infection can lead to serious illness, particularly in older adults.
Between 2001 and 2015 in Wisconsin, three deaths were reported among confirmed cases.
Among confirmed cases:
- 64% were male
- 68% were over age 60
- 96% occurred between April and October
Most cases, however, were managed outside the hospital, with 35% of confirmed cases treated in the community.
Transmission Beyond Tick Bites
Babesia transmission is not limited to tick exposure.
Cases of transfusion-transmitted babesiosis were reported prior to implementation of blood screening programs.
Perinatal transmission has also been described, highlighting additional pathways of infection beyond tick bites.
Geographic Expansion of Babesia Cases Wisconsin
The geographic spread of Babesia in Wisconsin has been substantial.
Between 2001–2005, 20 counties reported confirmed cases. This increased to 30 counties between 2006–2010 and 40 counties between 2011–2015.
This expansion suggests that Babesia risk is increasing across a broader region.
Diagnostic Challenges
The true number of Babesia cases Wisconsin may be underestimated.
Blood smear testing has limited sensitivity compared with PCR, which can detect lower levels of parasitemia.
This limitation may contribute to underdiagnosis, particularly in milder or early cases.
Clinical Perspective
Babesia cases Wisconsin reflect broader trends in tick-borne disease expansion.
Clinicians should consider Babesia infection in patients with compatible symptoms, especially in regions where cases are increasing.
Awareness of coinfections is important, as overlapping infections may complicate diagnosis and treatment.
Clinical Takeaway
Babesia cases Wisconsin have increased significantly, with expanding geographic distribution and multiple transmission pathways.
Improved awareness and diagnostic strategies may help identify cases earlier and guide appropriate treatment.
References
- Stein E, Elbadawi LI, Kazmierczak J, Davis JP. Babesiosis Surveillance – Wisconsin, 2001-2015. MMWR Morb Mortal Wkly Rep. 2017;66(26):687-691.
- Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes Tick-Borne Pathogens. Trends Parasitol. 2015.
- Eickhoff C, Blaylock J. Tickborne diseases other than Lyme. Cleve Clin J Med. 2017;84(7):555-567.
Related Reading
- Babesia and Lyme: What Patients Need to Know
- Study Raises Concerns for Babesia Patients and Blood Banks
- Babesia Becomes the Number 2 Tick-Borne Illness in the Hudson Valley
- Sweats May Be a Sign of Babesia
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
I wish that I could see Dr Cameron I live on the Illinois Wisconsin border and I have a positive Lyme test but my real problem is the symptoms that I have babesia and I need treatment if I do definitely have it. Can’t get a Dr to order the test and not sure if ins will cover the expense. So in need of help.
I agree with trying to get a dr to order a test. I had a lymes test came up negative but I have never felt right since I had it. lots of leg pain, super fatigue. why can’t we get tested at a county nurse office or something like that? Does the tick look the same for both. i had the tick but the dr said they don’t need it so i am pretty sure i dumped but i could look. what i do have are 2 pics of my arm with bite area very red and looks infected. please advise. thank you
The test are not as reliable as I would like. I have to use clinical judgement to determine who should get treated and what to treat with if the tests are negative. Pictures can be difficult to interpret.