3. INTRODUCTION-
Caused by O.tsutsugamushi
“tsutsuga”-dangerous “mushi”-mite
Occurs in Japan, Sumatra, Australia and islands
along the Western Pacific coast.
Disease transmitted by- larval form of Mite
(Trombicula deliensis)
Incubation period-7-10 days
Case fatality-10-60%
Scrub typhus-MICRO MGMC&H, Jaipur
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O.tsutsugamushi
4. INFECTION-
Larval form is known as chiggers.
Found in areas of suitable climate, plenty of
moisture and scrub vegetation.
Microbes are transmitted transovarianlly in all
mites.
Various rodents and birds also act as
reservoirs.
Scrub typhus-MICRO MGMC&H, Jaipur
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CHIGGER
5. Scrub typhus-MICRO MGMC&H, Jaipur
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Four factors are
essential for the
establishment of
infection, namely, co-
existence and intimate
relationship among-
6. CLINICAL FEATURES-
A necrotic lesion (eschar) occurs at the
site of bite in the skin.
Severe headache
Chills
Fever
Conjunctivitis
Maculopapular rash
Enlarged spleen and lymph nodes
Severe cases –encephalitis and
pneumonia
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MACULOPAPULAR RASH
ESCHAR
8. PRE REQUISITE -
They are highly infectious, their isolation should be attempted only in labs
equipped with appropriate safety measures.
UNABLE TO GROW ON CELL FREE MEDIA.
Scrub typhus-MICRO MGMC&H, Jaipur
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11. ISOLATION -
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Blood clot in skimmed milk is inoculated
intraperitoneally in male mice.
Animals are to be observed for 3-4
weeks. Temperatures are recorded
daily.
RESULT- animal becomes ill and
develop ASCITIS.
12. Demonstration-
Smears are taken from peritoneum, tunica and spleen of
infected animals.
Stained by- GIEMSA STAIN
Culture used- 1. YOLK SAC OF CHICK EMBRYO
2. TISSUE CULTURE
3. Vero and MRC5 CELL CULTURES
(not suitable for primary inoculation)
Identified by- IMMUNOFLUOESCENCE TEST
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TISSUE CULTURE
13. SEROLOGY
Weil felix test
Scrub typhus-MICRO MGMC&H, Jaipur
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Others-
• Compliment fixation test
• Latex agglutination test
• Enzyme immune assay
14. Weil-Felix Test
Developed by Weil and Felix in 1916.
Some Proteus (OX19, OX2, OXK) strains are agglutinated by sera of patients
with rickettsial infections.
This is due to the antigenic sharing between species of proteus and
rickettsia.
It is an eg. of heterophile agglutination test.
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DISEASE
AGGLUTINATION WITH PROTEUS STRAIN
OX19 OX2 OXK
Scrub typhus - - +++
15. Scrub typhus-MICRO MGMC&H, Jaipur
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Tetracyclines and chloramphenicol
General measures-
Control of vectors and
animal reservoir.
Vaccination-
There is no safe and
effective vaccine.