Scrub typhus survey of Biak and Owi islands: ectoparasites of small mammals and rickettsial isolations.

A survey of smnall mammals and their ectoparasites was conducted on the islands of Biak and Owi, Indonesia, in August 1976. Two species of chiggers known to serve as vectors of scrub typhus were found: Leptotrombidium (Leptotrombidium) deliense from Rattus exulans, R. ruber, and R. r. septicus; L. (L.) flectcheri from R. exulans, R. leucopus and R. r. septicus. Rickettsia tsutsugamushi was isolated from the spleens of R. exulans and R. r. septicus. The favored ecotype of the chigger and rat hosts of R. tsutsugamushi appeared to be coarse, low-lying native vegetation on a porous coralline soil. These and similar nearby coral islands should be considered high risk areas for scrub typhus.