Department of Entomology, United States Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand
Address for correspondence: Kriangkrai Lerdthusnee, Department of Entomology, USAMC-AFRIMS, 315/6 Rajvithi Rd., Phya Thai, Bangkok 10400, Thailand.
kriangkrail{at}amedd.army.mil
Ann. N.Y. Acad. Sci. 990: 205-212 (2003).
We previously reported
Orientia tsutsugamushi detection from
tissue samples (kidney, liver, spleen, and whole blood) of 12
wild-caught rodents from Chiangrai Province, northern Thailand.
Of the 30 chiggers individually removed from scrub typhus-infected
rodents, 2 were found positive for
O. tsutsugamushi. We further
characterized the
O. tsutsugamushi detected from these rodents
and chiggers by RFLP using three different enzyme digestions.
All 14
O. tsutsugamushi samples (12 from tissue samples and
2 from chiggers) showed different digestion patterns when compared
to those of reference strains (Karp, Kato, and Gilliam). Interestingly,
nine RFLP profiles were observed from these 14 samples suggesting
the presence of high genetic diversity of
O. tsutsugamushi in
this area. Furthermore, one sample displayed the same RFLP pattern
as that of
O. tsutsugamushi mild resistant strain previously
isolated from scrub typhus patient in Chiangrai. Of the two
samples from positive chiggers, only one was found to have a
similar RFLP pattern to that of its host rodent. DNA sequencing
of the entire 56 kDa genome of these
O. tsutsugamushi samples
is in progress.
