The New Human Babesia sp. FR1 Is a European Member of the Babesia sp. MO1 Clade

Abstract

In Europe, <i>Babesia divergens</i> is responsible for most of the severe cases of human babesiosis. In the present study, we describe a case of babesiosis in a splenectomized patient in France and report a detailed molecular characterization of the etiological agent, named <i>Babesia</i> sp. FR1, as well as of closely related <i>Babesia divergens</i>, <i>Babesia capreoli</i> and <i>Babesia</i> sp. MO1-like parasites. The analysis of the conserved 18S rRNA gene was supplemented with the analysis of more discriminant markers involved in the red blood cell invasion process: <i>rap-1a</i> (rhoptry-associated-protein 1) and <i>ama-1</i> (apical-membrane-antigen 1). The <i>rap-1a</i> and <i>ama-1</i> phylogenetic analyses were congruent, placing <i>Babesia</i> sp. FR1, the new European etiological agent, in the American cluster of <i>Babesia</i> sp. MO1-like parasites. Based on two additional markers, our analysis confirms the clear separation of <i>B. divergens</i> and <i>B. capreoli</i>. <i>Babesia</i> sp. MO1-like parasites should also be considered as a separate species, with the rabbit as its natural host, differing from those of <i>B. divergens</i> (cattle) and <i>B. capreoli</i> (roe deer). The natural host of <i>Babesia</i> sp. FR1 remains to be discovered.