In Europe, known reservoirs of "Borrelia burgdorferi" were 9 small mammals, 7 medium-sized mammals and 16 species of birds (including passerines, sea-birds and pheasants). These animals seem to transmit spirochetes to ticks and thus participate in the natural circulation of B. burgdorferi in Europe. The house mouse is also suspected as well as other species of small rodents, particularly in Eastern Europe and Russia. "The reservoir species that contain the most pathogens are the European roe deer "Capreolus capreolus"; ""it does not appear to serve as a major reservoir of B. burgdorferi"" thought Jaenson & al. (1992) (incompetent host for "B. burgdorferi" and TBE virus) but it is important for feeding the ticks, as red deer and wild boars ("Sus scrofa"), in which one "Rickettsia" and three "Borrelia" species were identified", with high risks of coinfection in roe deer. Nevertheless, in the 2000s, in roe deer in Europe ""two species of Rickettsia and two species of Borrelia were identified"".