Human Babesiosis in Europe

Abstract

Babesiosis is attracting increasing attention as a worldwide emerging zoonosis. The first case of human babesiosis in Europe was described in the late 1950s and since then more than 60 cases have been reported in Europe. While the disease is relatively rare in Europe, it is significant because the majority of cases present as life-threatening fulminant infections, mainly in immunocompromised patients. Although appearing clinically similar to human babesiosis elsewhere, particularly in the USA, most European forms of the disease are distinct entities, especially concerning epidemiology, human susceptibility to infection and clinical management. This paper describes the history of the disease and reviews all published cases that have occurred in Europe with regard to the identity and genetic characteristics of the etiological agents, pathogenesis, aspects of epidemiology including the eco-epidemiology of the vectors, the clinical courses of infection, diagnostic tools and clinical management and treatment.

Keywords: Babesia divergens; Babesia microti; Babesia venatorum; European babesiosis; Ixodes ricinus; clinical cases; diagnosis; epidemiology; parasite identity; treatment.

Figure 1

Babesia divergens in a Giemsa-stained thin blood smear. Round (A), paired pyriform (B), tetrad (Maltese cross) (C) and multiple parasite (D) forms are indicated. Similar round and paired pyriform forms have been observed in infections of B. venatorum, and round and tetrad forms occur in B. microti infections. Multiple parasite-infected erythrocytes are often seen in high parasitemias. © Estrella Montero, Luis Miguel Gonzalez.

Figure 2

The relative length, positions and heterologies of 18S rRNA sequences of Babesia species isolates from human cases compared to the reference sequence U16370. Numbers refer to positions in the reference sequence. Identity scores are according to Clustal Omega. ‘-’ indicates that the base was missing.