Hundreds of cases have been reported since the first domestic case of human babesiosis was reported in 1966. An increasing trend over the past 30 years may be the result of restocking of the deer population, curtailment of hunting, and an increase in outdoor recreational activities. Although the most life-threatening cases occur in patients who are elderly, immunocompromised, or have undergone splenectomy, most patients with babesiosis are asymptomatic, which may result in underreporting of the disease across all age groups. Although rare, it is symptomatic and often fatal. Like its US counterpart, babesiosis in Europe is also seen in patients who have undergone splenectomy.
Most cases are asymptomatic and improve spontaneously without treatment.
These patients experience more severe symptoms for a longer duration than those with either disease alone. In Europe, babesiosis is a life-threatening disease. No difference in seropositivity exists among age groups. Adequate reporting is a major problem, especially in children, because of masking by other infections and the disease's history of occurrence in elderly patients. Patients report a history of travel to an endemic area between the months of May and September.