Unit Code 8148:
Scrub Typhus Antibodies, Serum
Useful For
As an aid to the diagnosis of scrub typhus infections
Clinical Information
Scrub typhus is an acute infectious disease transmitted to man by
the bites of mites. Orienta tsutsugamushi, the etiologic agent, is
transmitted into the skin by the bite of the larval mite.
The spectrum of clinical severity ranges from inapparent and mild
to severe or fatal. An initial lesion usually develops at the site of a
chigger bite. It later becomes papulovesicular and forms a black scab
which becomes the eschar. Regional lymphadenopathy is common
followed by a macular rash which occurs between the 5th and 8th days of
illness. Fever is common and may rise to 40-45 degrees C. Conjunctivitis
and hepatosplenomegaly are also common manifestations. Multi-organ
vasculitis of the small blood vessels occurs. Acute hepatitis or
granulomatous hepatitis can be a complication of scrub typhus.
Treatment is with chloramphenicol or tetracyclines.
Reference Values
Negative to a titer of 1:40 is normal.
A 4-fold or greater rise in paired sera titer indicates recent infection.
See "Virology" in Special Instructions for additional interpretive
information.
Interpretation
An agglutinin titer of > or =1:160 is suggestive of active infection.
Agglutinins appear 7-15 days after the onset of disease. Titers peak
during the third week and decline rapidly over the next few months.
Antibodies are found in only approximately 50% of cases within the
second week of illness.
A 4-fold or greater rise in paired sera titer is suggestive of recent
infection. However, only 50-70% of patients with scrub typhus
exhibit a 4-fold rise in titer.
Cautions
No significant cautionary statements
Special Instructions and Forms
Clinical Reference
1. Chi WC, Huang JJ, Sung JM, et al: Scrub typhus associated with
multiorgan failure: a case report. Scand J Infect Dis 1997;29:634-635
2. Chien RN, Liu NJ, Lin PY, Liaw YF: Granulomatous hepatitis
associated with scrub typhus. J Gastroenterol Hepatol 1995;10:
484-487
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