Rapid Increase of Scrub Typhus, South Korea, 2001–2006

SFG rickettsiae and R. typhi have been observed, but a lack of cross-reactions has also been observed (9). It has been noted (10) that when cross-reactions were observed between R. felis and both R. conorii and R. typhi, the infection was probably related to R. felis. When cross-reactions were observed between R. felis and only R. typhi, the causative agent was most probably of the typhus group. R. felis infections occur globally and are linked to the worldwide distribution of vectors, but the occurrence is relatively rare when compared with the high frequency of R. felis infections related to flea infestation. Human infections remain poorly characterized and are apparently underappreciated, possibly because of the lack of specific signs and symptoms. Further characterization of the interactions between R. felis and fleas could elucidate the particular epidemiology and pathology of flea-borne spotted fever. This work was supported by the French Centre National de la Recherche Scientifique.