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Scrub typhus-MICRO M
GMC&H, Jaipur
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( CHIGGER BORNE TYPHUS)
SCRUB TYPHUS
CHIGGER
Scrub typhus-MICRO MGMC&H, Jaipur
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RICKETTSIACEAE
RICKETTSIA
R.prowazekii
R.typhi
R.rickettsii
R.conori
R.australis
R.siberica
R.akari
ORIENTIA O.tsutsugamushi
FAMILY GENUS SPECIES DISEASE
CLASSIFICATION
• True bacteria• Obligate intracellular
parasite
Mostly by ticks
mites
Epidemic typhusBrill-Zinsser disease
Endemic typhus
Rocky-mountain spotted fever
Boutonneuse fever
Australian tick typhus
Siberian tick typhus
Rickettsial pox
Scrub typhus
Scrub typhus-MICRO MGMC&H, Jaipur
3INTRODUCTION-
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%
O.tsutsugamushi
Scrub typhus-MICRO MGMC&H, Jaipur
4INFECTION-
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.
CHIGGER
Scrub typhus-MICRO MGMC&H, Jaipur
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ZOONOTIC TETRAD
Rats(rodents)
O.tsutsuga-mushi
Transitional form of vegetation
chiggersFour factors are essential for the establishment of infection, namely, co-existence and intimate relationship among-
Scrub typhus-MICRO MGMC&H, Jaipur
6CLINICAL 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
MACULOPAPULAR RASH
ESCHAR
Scrub typhus-MICRO MGMC&H, Jaipur
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LABORATORY DIAGNOSIS
• SPECIMENS• DIRECT MICROSCOPY• CULTURE (ISOLATION OF ORGANISM)
• SEROLOGY• MOLECULAR METHODS
Scrub typhus-MICRO MGMC&H, Jaipur
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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
9SPECIMENS-
For culture- Blood Tissue
For serological test serum
Scrub typhus-MICRO MGMC&H, Jaipur
10DIRECT MICROSCOPY
GIEMSA STAIN Purple colored basophilic inclusions
MACHIAVELLO’S STAIN Red colored inclusions
Scrub typhus-MICRO MGMC&H, Jaipur
11ISOLATION -
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.
Scrub typhus-MICRO MGMC&H, Jaipur
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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
TISSUE CULTURE
Scrub typhus-MICRO MGMC&H, Jaipur
13SEROLOGY
Weil felix test Others-
• Compliment fixation test• Latex agglutination test• Enzyme immune assay
Scrub typhus-MICRO MGMC&H, Jaipur
14Weil-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.
DISEASE
AGGLUTINATION WITH PROTEUS STRAIN OX19 OX2 OXK
Scrub typhus - - +++
Scrub typhus-MICRO MGMC&H, Jaipur
15Treatment-Tetracyclines and chloramphenicol
General measures-Control of vectors and animal reservoir.
Vaccination-There is no safe and effective vaccine.
Scrub typhus-MICRO M
GMC&H, Jaipur
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THANK YOU BY- UMANG JUNEJA