ABSTRACT
VALIDATED SPECIES A detailed list of rickettsial species of possible or undetermined pathogenicity in humans is provided in Table 1.
Rickettsia asiatica In June 1993, a rickettsial isolate named IO-1 was obtained from Ixodes ovatus ticks in Fukushima. Since that time, 32 additional strains with identical gltA sequences IO-1 have been obtained from I. ovatus ticks in Japan (8,9). Preliminary results of mouse serotyping and sequencing of the entire 16S rRNA and gltA genes demonstrated that strain IO-1 exhibited unique serotypic and genotypic characteristics (10,11). More recently, using multilocus sequence comparison, five rickettsial isolates from I. ovatus collected at various locations in Japan were found to be identical to each other and represent a novel species that was named R. asiatica (12). The type strain of R. asiatica sp. nov. is IO-1. Phylogenetically this species is close to R. helvetica, a possible human pathogen (see below). No information is currently available about the possible pathogenicity of R. asiatica for vertebrate hosts. The currently known geographical distribution is restricted to Japan (12).
