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