This document presents a case study of an 18-year-old female diagnosed with scrub typhus. She presented with fever, cough, vomiting, abdominal pain, and shortness of breath. Examination revealed conjunctival suffusion, basal crepitations in the lungs, and abdominal guarding. Tests showed anemia, thrombocytopenia, and elevated liver enzymes. A Weil-Felix test was positive for OX-K antigen, leading to a diagnosis of scrub typhus. She was treated with doxycycline and supportive care and made a full recovery.

1. Scrub Typhus- case presentation
Dr. D.P.Bansal (M.D.,D.M.)
Dr. Mohd Viquasuddin Saim
DNB medicine resident
Medwin hospital

2. Case presentation
• An 18 year old female , resident of
Mahbubnagar district was admitted with
history of fever since 2 weeks, cough since 2
weeks, vomitings since 10 days, pain abdomen
and shortness of breath since 3 days
• Fever was continuous, high grade, subsiding
on medication and not associated with chills
• Cough was non productive

3. Case presentation
• Vomitings were 3 to 4 episodes/day, non
projectile, non bilious, associated with nausea
aggravated by food intake.
• pain abdomen was diffuse, intermittent,
colicky in nature, aggravated on food intake
and associated with constipation
• Shortness of breath was present at rest , not
asssociated with chest pain. There was no
orthopnea or PND.

4. Case presentation
• o/e :
• Conjunctival suffusion +
• Lungs : BAE +, b/l basal crepts +
• p/a : guarding +
• Heart sounds : normal
• CNS : NAD

5. Case presentation
• Evaluation of the patient revealed
• Anemia (Hb : 8.1)
• Thrombocytopenia (63,000)
• WBC : 7500
• Chest x ray : b/l diffuse haziness s/o
pneumonia
• Weil felix test was positive for OX-K antigen
• LFT’s were raised

6. Case presentation
• Dengue IgG and IgM were negative
• Dengue NS1 antigen was negative
• HBsAg, HAV, HCV, HIV I & II were negative
• Leptospira IgM was negative
• Blood culture did not reveal any bacterial
growth , WIDAL test was negative
• Smear for Malarial parasite and parasite F and
V were negative

7. Case presentation
• A diagnosis of scrub typhus was made and
patient was treated with Doxycyline, IVF,
antipyretics, and antiemetics.
• Daily platelet counts and liver parameters
were monitored.
• Patient improved symptomatically and was
discharged after 10 days.

8. Scrub typhus : historical background
• Also known as Japanese river fever
• ‘tsutsugamushi’ in japanese means tsutsuga =
disease, mushi = bug
• Disease was also endemic in south and
southeast asia
• Major infectious disease in asia during second
world war
• Scrub typhus research laboratory was
established in Imphal, India

9. epidemiology
• Important and widespread cause of febrile
illness in rural areas of asia
• Caused by Orientia tsutsugamushi ( formerly
Rickettsia tsutsugamushi )
• Contracted via the bite of the larval stage (
chigger) of trombiculid mite.
• Infected mites are characteristically found in
discrete foci called ‘mite islands’

10. epidemiology
• Mite islands can occur in a wide range of
vegetations types like :
• Scrub (tall-growing coarse grass)
• Forests
• Gardens, beaches
• Paddy fields
• Bamboo patches
• Oil palm or rubber estates

11. epidemiology
• O.tsutsugamushi is an obligate intracellular
bacterium
• Its maintained transovarially in mite
population and rodents
• Larval stages normally feed on rodents
• Humans are accidental hosts
• Recently a new species O.chuto has been
discovered in UAE

12. chigger

13. pathogenesis
• O. tsutsugamuhi infects endothelial cells,
macrophages and PMNs.
• Bacteria uses host fibronectin interactions
with its 56-kDA antigen (TSA56) for
attachment.
• Invades host cell via induced phagocytosis
• Enters phagosome and then escapes into
cytoplasm

14. pathogenesis
• Replicates via binary fission and then is released
covered by host cell membrane
• Recent evidence suggests pathophysiology of
o.tsutsugamushi is different from endothelium
targeting Spotted fever group.
• Mononuclear cell activation was more prominent
than endothelial cell activation
• Primary cytopathic destruction of endothelium of
blood vessels causing vasculitis

15. Clinical features
• Presents as a systemic vasculitic infection
• Most of the pathogenesis is unknown
• Symptoms occur between 6 to 10 days after
mite bite
• Typically presents with fever,
lymphadenopathy, macular-maculopapular
rash, severe headache and myalgia
• muscle tenderness is minimal or absent

16. Clinical features
• Also seen are
• Nausea and vomiting
• Diarrhea
• Constipation
• Conjunctival suffusion
• Reversible sensorineural deafness

17. Clinical features
• A painless papule occurs at the site of the bite
prior to the onset of disease symptoms
• This painless papule later ulcerates and
transforms into a black crust or ‘eschar’ in
variable proportion of patients
• eschar is not noticed in all patients because of
variability in thoroughness of physical
examinations and immunological factors

18. Eschar

19. complications
• Jaundice
• Meningoencephalitis
• Myocarditis
• Interstitial pneumonia leading to ARDS
• Renal failure
• Mortality was 42 % in preantibiotic era
• Mortality still high in rural areas

20. Immunity
• Remarkably short lived
• Lasts only a few months
• Highly strain specific
• Insufficient to protect from infection with
other strains

21. diagnosis
• Gold standard diagnostic tests are
• Immunofluorescent assay (IFA) and indirect
immunoperoxidase test (IIP) based on cell-culture
derived O.tsutsugamushi antigens
• These antigens are applied to paired
admission and convalescent samples
• These are not standardized and are usually
unavailable in poor tropical areas

22. diagnosis
• WEIL-FELIX test
• This test was developed in 1916 for typhus fever
• This is based on positive agglutination of Proteus
vulgaris (OX19) by the serum from patients with
all forms of typhus except scrub typhus
• In 1924, Dr. AN Kingsbury unknowingly
introduced a strain of Proteus mirabilis in malaya
where scrub typhus is endemic and strong
agglutinations were seen

23. diagnosis
• WEIL-FELIX test
• The antigen was termed as OXK (K=Kingsbury)
• The discovery of this antigen led to the
identification of two different types of typhus
fevers (scrub typhus and murine typhus)
• Sensitivity and specificity is low
• its predictive value can be increased by testing
both acute and convalescent phase samples
and observing rise in antibody titre

24. diagnosis
• WEIL-FELIX test
• low sensitivity means it gives high percentage
of false negative results.
• common in case of Scrub Typhus.
• low specificity meaning false positive results
are obtained in leptospirosis, and relapsing
fever , Proteus infections, brucellosis and
acute febrile illness

25. Diagnosis
• Anti-O.tsutsugamushi IgM and IgG based rapid
diagnostic tests have been developed but
evaluation is pending
• ELISA also can be used
• Benefits of ELISA include multiple tests at one
time, inexpensive, sensitive, specific.
• PCR methods have also been developed
• Target genes are 47 Kda, groEL genes

26. diagnosis
• Can be cultured from blood
• takes several weeks
• Special tissue culture techniques
• A bioSafety level 3 facility is mandatory
• Samples taken from eschars can be used for
both PCR-based or immunohistochemical
diagnosis due to high bacterial loads

27. Differential diagnosis
• Typhus : distinguished only be serological tests
• Malaria : by stained blood films
• Arbovirus infections : by serological methods
• Leptospirosis : by PCR or culture
• Relapsing fever : by blood smear, serology
• Meningococcal disease : by blood and CSF
cultures
• Typhoid : blood and bone marrow cultures
• Viral fevers

28. treatment
• It is very responsive to treatment
• Appropriate antibiotics should be given
empirically if the diagnosis is suspected
• D.O.C is Doxycycline if there are no
contraindications
• Adult oral dose of 100mg twice daily for 7
days
• Tetracycline 500mg every 6 hours for 7 days
can also be used

29. treatment
• Azithromycin (1000-500mg) on the first day
followed by 500-250mg daily for 2 days is an
effective alternative
• Azithromycin has also been shown to be
effective in single dose
• Azithromycin is particularly useful in
pregnancy where tetracyclines are
contraindicated

30. treatment
• Chloramphenicol is an alternative to the
tetracyclines (500 mg every 6 hours in adults
or 50-75 mg/kg per day in children for 7 days)
• Other antibiotics which have been used
successfully are Roxithromycin, telithromycin
and Rifampicin
• Fluoroquinolones have been assocaited with
treatment failures and should not be used.

31. prevention
• Preventive measures include :
• Wearing protective clothing
• Treatment of clothing with repellants or
acaricides
• Application of DEET to exposed skin
• No protective vaccine is available

32. -----------------
• Thank you