Rickettsiae in Ticks, Japan, 2007–2011

were typical of lymphangitis-associated rickettsiosis, and most cases of rickettsioses in southern France in the spring are caused by R. sibirica mongolitimonae. Clustered cases of SFG rickettsiae infection have been reported in Europe, including southern France (3,6). In 2007, R. conorii and R. massiliae infections in humans were reported (3). In 2010, cases for which we were unable to discriminate between R. conorii and R. massiliae infections occurred in a family (6). In these 2 studies, clustered cases of SFG rickettsiosis involved Rh. sanguineus ticks. Clustered cases appeared to be related to an increase in aggressiveness of ticks toward humans during warmer periods (3). In our study, no correlation was identified with warmer weather. R. sibirica mongolitimonae is most frequently associated with Hyalomma spp. ticks (1,2,4). However, 1 case of infection with this bacterium was associated with Rh. pusillus ticks collected in Portugal (7); DNA from this bacteria was also identified in an Rh. pusillus tick collected from a mongoose. The European wild rabbit is the primary host of Rh. pusillus ticks. However, these ticks have been found on wild carnivorous animals, dogs, and domestic cats (8); these ticks can bite humans (8). Moreover, R. massiliae and R. sibirica mongolitimonae were found in Rh. pusillus ticks from Spain (9), and SFG rickettsiae were found in ticks from Sardinia (10). Therefore, Rh. pusillus ticks appear to be an emerging vector for R. sibirica mongolitimonae in Europe.