scrub Typhus- Dr. Mausumi saha.ppt

Scrub Typhus

1. Scrub Typhus

3. .

4. .
•Rickettsioses of which scrub is the commonest has
been clearly reported from several state in India
including J & K, HP, Uttarakhand, Bihar, West
Bengal, Meghalaya, Rajasthan, Maharashtra,
Karnataka, TN and Kerala".
Reason of under diagnosed:
•Non-specific clinical presentation,
•Lack of access to the specific diagnostic facility
•Low index of suspicion by the clinician.
Ref: "Guideline on Diagnosis and Management of Rickettsial Diseases (2015)", ICMR

5. Scrub typhus
•Agent : Orientia(formerly Rickettsia) tsutsugamushi.
•Reservoir : Trombiculidmites (“chiggers”).
•Vector : Disease transmitted to humans and rodents by
the bite of an infected chigger.

6. Microbiological aspects
Orientiatsutsugamushi:
•a Gram-negative bacterium of familyRickettsiaceae.
•An intracellular pathogen
•Many antigenic strains have been identified over the
years from the original three strains (Karp, Kato, and
Gilliam).
•Infection with one strain of the pathogen does not
provide immunity to the other strains.

7. Clinical features
•Incubation period: 10-12 days(varies from 6 to 21
days)
•Acute fever(104-105 F) with chill, malaise,
conjunctival irritation.
•Macular rash
•Lymphadenopathy, lymphocytosis
•Headache, cough, myalgia
•Eschar formation(5
th
day of illness) most specific
manifestation of scrub typhus.

8. Escher

10. Complication
•Pneumonitis
•Hepatitis
•Meningoencephalitis
•DIC
•Multi organ failure

11. Diagnosis of Scrub typhus
Weil-Felix test:
•The sharing of antigens between rickettsia and
proteusis the basis of this heterophileantibody test.
•It demonstrates agglutinins to Proteus vulgaris strain
OX 19, OX2 and OX K
•Lacks high sensitivity and specificity (43%–59%).
•Still useful and inexpensive diagnostic tool.
•Only after 5-7 days of onset of fever.
•Titre of 1:80 -possible infection.

12. .
IgM and IgG ELISA:
•SignificantIgMantibody titre is observed atthe end
of 1st week, whereas IgGantibodies appear at end
of 2nd week.
•Cut-off value is optical density of 0.5.

13. .
Polymerase chain reaction (PCR):
•Rapid and specific
•Target the gene encoding the major 56 kDaand/or
47 kDasurface antigens
•Can be used to detect rickettsial DNA in whole blood,
buffy coat fraction or tissue specimen.
•Best within the first week for blood samples

14. .
•Immunufluoroscence assay (IFA): serological “gold
standard”
•Indirect immunoperoxidase assay (IPA): comparable
result as IFA but requires special instrument and
experienced personnel for interpretation of the test.

15. Treatment
•Treatment must be initiated empirically in suspected
cases without awaiting laboratory confirmation, as
morbidity and mortality escalate rapidly with each
day of treatment delay.
•Treatment should not be discontinued solely on the
basis of a negative test result

16. At Primary level
•a) Recognition of disease severity. If the patient
comes with complications to primary health facility
and treating physician considers it as rickettsial
infection, treatment with Doxycyline should be
initiated before referring the patient.
•b) Referralto secondary or tertiary centre in case of
complications like ARDS, acute renal failure,
meningo-encephalitis, multi-organ dysfunction.

17. .
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18. .

19. At secondary and tertiary care:
a) The treatment as specified above in uncomplicated
cases.
b) In complicated cases :
i) Intravenous Doxycycline100 mg twice daily in 100 ml
normal saline to be administered as infusion over half an
hour initially, followed by oral therapy to complete 7-15
days of therapy.
OR
ii) Intravenous Azithromycin in the dose of 500 mg IV in
250 ml normal saline over 1 hour once daily for 1-2 days
followed by oral therapy to complete 5 days of therapy.
(contd.)

20. .
Or
iii) Intravenous Chloramphenicol50-100 mg/kg/day in
6 hourly (divided) doses to be administered as infusion
over 1 hour initially, followed by oral doses to complete
7-15 days of therapy.
iv) Management of the individual complications should
be done as per the existing practices.
Doxycycline and/or Chloramphenicol resistant strains have been seen in South-East Asia. These strains are
sensitive to Azithromycin."

21. Prevention
Vector control:
•Environmental control –cleaning vegetation
•Application of insecticides eg. Lindaneor chlordane
to ground & vegetation
•Personal protection -
Impregnating cloths & blankets with miticial
chemicals (benzyl benzoate)
Application of mite repellents (diethyltoluamide)
to exposed skin surfaces.
No effective vaccine.

22. The Best diagnostic test!!!
DOXYCYCLINE CHALLENGE!!!

23. Take home
•Rickettsial diseases are present in India and in our
state also..
•Suspect Rickettsia early in cases of PUO.
•Any PUO of infectious etiology, more than 7 days,
negative for Malaria, dengue ,Typhoid and especially
if the patient is from rural or suburban areas, with
features of multiorgan dysfunction ,it should be
taken as a rickettsia unless proved otherwise.
•If suspicion is high, don’t hesitate to go for
Doxycycline challenge…………as it is life saving and
safe even in 1 year old child.

24. Thanks for kind
attention