Figure 5-14. Trombicula mite larva.
Figure 5-15. Freeliving adult mite.
5-46. SCRUB TYPHUS
a. General. Scrub typhus (mite-borne typhus, tsutsugamushi disease) is a
febrile infectious disease caused by Rickettsia tsutsugamushi and is transmitted to man
by the bite of infected larvae of Trombiculid mites.
(1) Clinical course. The clinical course resembles that of other typhus-like
A primary lesion (eschar) occurs at the site of attachment of the mite
4 or 5 days after attachment.
Onset of the acute febrile stage is from 6 to 21 days, usually 10 to
12, after attachment of the chigger.
In the absence of specific therapy, fever persists for about 2 weeks.
In the general population, from 1 % to 40% of untreated cases
Scrub typhus can recur in the same individual, since one attack
confers long-term immunity only to the specific strain of R. tsutsugamushi that caused
the initial attack.