Aspects nouveaux du rôle de vecteur joué par Ixodes Ricinus L. en Suisse. Note préliminaire

The authors, after having recalled their recent work on <i>Ixodes ricinus</i> ecology, give the new results about the part played by this species in the transmission of different infectious agents in Switzerland. <i>I. ricinus</i> was already known to be the most important vector of the tick borne encephalitis virus, and of protozoans of the <i>Babesia</i> genus. In this article, we describe the existence in the hemolymphe of different </i>I. ricinus</i> populations, of a rickettsia species related to the RMST group (Rocky-Mountain Spotted Fever), of a trypanosome, which is close to <i>T. theileri</i>, and of an infectious larval form (L3) of <i>Dipetalonema rugosicauda</i>. An outline is suggested with the object of illustrating the functioning of a natural foci of tick encephalitis. The biological significance of the unusual presence of trypanosomes and of larval filariae in ticks is also discussed. The authors underline the fact that rickettsia, trypanosomes and filarial forms are observed for the first time in Swiss <i>I. ricinus</i>.