Page 127 - JSOM Spring 2020

typhus may also occur with a nonspecific febrile presentation,
mild systemic symptoms and without an obvious primary le-
sion. Other infections which may cause similar symptoms in-
cluding a black crusted lesion, such as rickettsial spotted fevers
and cutaneous anthrax, should also be considered. FIGURE 2 Adult and larval
mites on the head of a pin.
Scrub typhus is sometimes severe enough to cause organ dys-
function, including acute kidney injury, liver failure, pneumo-
nitis, acute respiratory distress syndrome, cardiac involvement, Source: Typhus Fevers, CDC.
and bleeding and blood clotting issues. Patients may experi- https://www.cdc.gov/typhus/
7
scrub/index.html
ence changes to mental status, meningitis, or meningoenceph-
alitis and may even become comatose. Presence of more severe
symptoms is associated with a higher mortality and is more
likely to occur in immunocompromised or otherwise weak-
ened patients.

Diagnosis
If the clinical presentation is consistent with scrub typhus,
appropriate treatment should be initiated without waiting for
confirmation from diagnostic testing. FIGURE 3 US Armed Forces
poster from World War II
warning about scrub typhus
There are multiple diagnostic testing options and they should risk. Wearing permethrin-
be used if available to confirm diagnosis. Serological testing impregnated clothing is still a
options for scrub typhus include immunofluorescence assay mainstay of prevention.
(IFA), rapid diagnostic tests and ELISA. Serology is considered
positive with elevated IgM antibodies or a 4-fold increase in
IgG antibodies (seroconversion) but may be falsely negative Source: US NLM Digital
early in the disease process. The gold standard of diagnosis is Collections, NLM, 1945.
http://resource.nlm.nih.
IFA; however, it is expensive, requires repeat testing, and will gov/101438591
not be available in the field. Alternative testing options include
polymerase chain reaction (PCR) and the Weil-Felix test. PCR
testing on samples from blood or eschar material is as useful
as serological testing. Weil-Felix testing has been phased out in
resource-rich areas and cannot differentiate Orientia sp. from
other rickettsial diseases but may be the only option available Importance in a Deployed Setting
in resource-poor regions. Scrub typhus remains a concern for troops deployed to the
Indo Asia-Pacific region, even for brief periods of time and
Treatment and Prevention even to urban areas. Scrub typhus is the most common rick-
10
ettsial disease in South Korea. Rodents captured outside ur-
Early treatment of scrub typhus is associated with improved ban foodservice buildings at Yongsan Garrison in Seoul and
outcomes and decreased mortality. The usual initial treatment in areas of tall grass at Dagmar North Training Area were
for scrub typhus is 100mg of oral doxycycline twice daily for found to carry O. tsutsugamushi. 11,12 In Japan there have been
7 days. If doxycycline is contraindicated, unavailable or if the recurrent outbreaks among US Marines at Camp Fuji since
patient does not improve as expected, alternative antibiotics the 1930s and rodents trapped in a grassy area near the golf
such as azithromycin and chloramphenicol have been shown course on Camp Zama were found to harbor mites which car-
to be effective therapy. Rifampin may also be used but only ried O. tsutsugamushi. 9,13
after ruling out tuberculosis. Limited studies have been con-
ducted on the efficacy of the different treatment options with With the recent discovery of scrub typhus cases outside of the
a recent review showing no difference between the different Asia-Pacific region it would be prudent to consider scrub ty-
antibiotics on primary outcomes of infection. Patients are phus from a preventative medicine and differential diagnosis
8
expected to become afebrile within 24 to 48 hours of start- standpoint in other areas of the world as well. If a patient has
ing treatment. If a patient is severely ill or worsening despite a clinical presentation concerning for scrub typhus, medical
appropriate oral antibiotics for 48 hours, they should receive providers should seriously consider it as the cause of illness
IV antibiotic therapy and alternative diagnoses should be se- even outside the “tsutsugamushi triangle,” initiating appropri-
riously considered. Although reported, the significance of ate antibiotic therapy to prevent severe complications of this
antibiotic-resistant scrub typhus is unclear and its clinical sig- potentially fatal infection. Although the US military has made
nificance is unknown. 9 advances in the prevention and treatment of scrub typhus, it is
still a factor to consider for military operations in the Asia-Pa-
Prevention of scrub typhus includes avoiding areas with dense cific region and beyond.
vegetation and rodents where the larval mites may be found,
using DEET-containing insect repellant, and wearing full- Disclaimer
length permethrin-treated gear. No vaccine is currently avail- The views expressed in this publication are those of the au-
able to prevent scrub typhus (Figures 2 and 3). thors and do not reflect the official policy or position of the

Scrub Typhus | 121