Investigation of the role of Blankaartia acuscutellaris (Acari: Trombiculidae) as a vector of scrub typhus in central Thailand.

Monthly collections of rodents were conducted in Phitsanulok Province, central Thailand in 1993 to investigate the role of the mite Blankaartia acuscurellaris as a vector of scrub typhus. Overall, a total of 41 rodents were collected and examined for the presence of the red colored larvae of B. acuscutellaris and yellow larvae of Leptotrombidium deliense and Ascoshoengastia sp. A total of 787 B. acuscutellaris and 1390 yellow larvae were placed into pools, triturated and isolation of Orientia tsutsugamushi attempted in laboratory mice. The sera of 8 of the collected rodents had elevated antibodies to O. tsutsugamushi indicating active infections; however, O. tsutsugamushi was not isolated from rodent tissues or pools of larvae. The results of this survey suggest that B. acuscutellaris may not be an important vector of scrub typhus, but more studies are needed in endemic areas.