Noor Fatima, MD; Steven Lippmann, MD
WMJ. 2025;124(1):3-4.
To the Editor:
Babesiosis, a tick-borne zoonotic disease, is an emerging health issue in the United States, including in Wisconsin. A parasite, Babesia microti, is primarily transmitted by deer ticks (Ixodes scapularis), the same vector responsible for Lyme disease. Uncommon modes of transmission include blood transfusions, organ transplants, and transplacental spread. Clinical manifestations range from fever, chills, headache, and myalgia – potentially fatal outcomes in immunocompromised people.
Babesiosis is most common in northeastern and some Midwestern regions of the United States (See Figure in full-text pdf). Its incidence has risen significantly – especially in the last decade – with a 25% increase reported between 2011 and 2019.1 This trend coincides with environmental deviations, including warmer climates and land development, which amplify human exposure to ticks. Data suggest that each 1 °C temperature increase correlates with an 18% rise in incidence, underscoring the impact of climate change on disease spread.2
The clinical history/patient presentation often indicates the diagnosis potential. Laboratory evidence includes anemia, thrombocytopenia, hyponatremia, elevated hepatic enzymes, and might include renal dysfunction. Confirmation comes through blood smear or polymerase chain reaction testing. Pharmacotherapy is a combination of atovaquone and azithromycin or clindamycin and quinine. Supportive care is provided. Severe cases may require exchange transfusions. Co-infections with other tick-borne diseases, such as Lyme disease or anaplasmosis, are common and may necessitate additional treatment with doxycycline.3
Prevention is important and comes through public awareness and tick avoidance. As the disease burden grows, there is need for advancements at clinical and laboratory diagnostic recognition, therapeutic options, and vaccine development. This multifaceted approach should mitigate the impact of disease in this part of the country.
REFERENCES
- Swanson M, Pickrel A, Williamson J, Montgomery S. Trends in reported babesiosis cases – United States, 2011-2019. MMWR Morb Mortal Wkly Rep. 2023;17:72(11):273-277. doi:10.15585/mmw.mm7211a1
- Walsh MG. The relevance of forest fragmentation on the incidence of human babesiosis: investigating the landscape epidemiology of an emerging tick-borne disease. Vector Borne Zoonotic Dis. 2013;13(4):250-255. doi:10.1089/vbz.2012.1198
- Ssentongo P, Venugopal N, Zhang Y, Chinchilli VM, Ba DM. Beyond human babesiosis: prevalence and association of babesia coinfection with mortality in the United States, 2015–2022: a retrospective cohort study. Open Forum Infect Dis. 2024;11(10):ofae504. doi:10.1093/ofid/ofae504