Display omitted •Babesiosis is a worldwide emerging tick-borne disease.•Infection can be acquired through tick bite, blood transfusion, organ transplantation, or transplacentally.•Babesiosis imposes a significant health burden, especially in the immunocompromised.•Diagnosis is confirmed by thin blood smear and/or PCR.•Antibiotic therapy consists of atovaquone and azithromycin or clindamycin and quinine. Babesiosis is a worldwide emerging tick-borne disease that is increasing in frequency and geographic range. It imposes a significant health burden, especially on those who are immunocompromised and those who acquire the infection through blood transfusion. Death from babesiosis occurs in up to 20 percent of these groups. Diagnosis is confirmed with identification of typical intraerythrocytic parasites on a thin blood smear or Babesia DNA using PCR. Treatment consists of atovaquone and azithromycin or clindamycin and quinine, and exchange transfusion in severe cases. Personal and communal protective measures can limit the burden of infection but it is important to recognize that none of these measures are likely to prevent the continued expansion of Babesia into non-endemic areas.