La Scola B. auteur aut IRD Bechah Y. auteur aut IRD Lepidi H. auteur aut IRD Raoult Didier auteur aut IRD text journalArticle eng text/pdf born digital access Until now, when a new Rickettsia species was isolated in a tick, it was not possible to predict whether it was a human pathogen or if it would cause a skin eschar at the infection site. Guinea pigs are injected intradermally with 25 different Rickettsia species or subspecies: 16 induced an eschar, 5 induced inflammatory lesions and 4 have no effect. We observed that the occurrence of skin eschars in this model was significantly correlated (P < 0.05) with observations of skin eschars in humans (14/16). The most common histological finding was mononuclear cell infiltration. Polymorphonuclear cell infiltration was observed for Rickettsia australis, Rickettsia japonica, and, as in humans, Rickettsia africae. The treatment of guinea pigs with corticosteroids prevents the apparition of eschar following Rickettsia bellii inoculation. Virulent, but not avirulent, Rickettsia prowazekii induced transient inflammatory lesions that were associated with dermal vasculitis, as is Rickettsia typhi. Therefore, the intradermal injection of Rickettsia in guinea pigs appears to be a relevant model for the prediction of the development of escharotic lesions following Rickettsia infection in humans. We speculate that skin eschar is the reflect of a local control avoiding extreme virulence. specialized Rickettsia Emerging rickettsiosis Eschar 052 47 3 128-133 2009 0882-4010 https://www.documentation.ird.fr/hor/fdi:010046347 10.1016/j.micpath.2009.06.004 0882-4010 [F B010046347] https://www.documentation.ird.fr/hor/fdi:010046347 https://www.documentation.ird.fr/intranet/publi/2009/09/010046347.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2009-10-07 2017-08-23 fdi:010046347 fre