RickettsiaceaeRickettsiaceaeGram –ve bacilliGram –ve bacilli

Obligate intracellular parasites of flee-GIT Obligate intracellular parasites of flee-GIT of arthropodof arthropod

In humans –infect vascular endothelial and In humans –infect vascular endothelial and reticuloendothelial cellsreticuloendothelial cells

Spotted feverSpotted fever -fever with rashes -fever with rashes Howard Taylor ricketts-Howard Taylor ricketts- 1906 1906

Genus RickettsiaGenus Rickettsia Genus OrientaGenus Orienta Genus EhrlichiaGenus Ehrlichia Genus CoxiellaGenus Coxiella BartonellaBartonella

Genus RickettsiaGenus Rickettsia

Typhus fevers and spotted feversTyphus fevers and spotted fevers

MorphologyMorphology Coccobacillary-Coccobacillary-

nonmotile,noncapsulated,cannot be nonmotile,noncapsulated,cannot be stained with gram stain,geimsa stain usedstained with gram stain,geimsa stain used

Electron microscop-structure similar to Electron microscop-structure similar to gram –ve bacilligram –ve bacilli

3 layerd cell call3 layerd cell call

Cultivation Cultivation

Unable to grow in cell free mediaUnable to grow in cell free media In cytoplasm of infected cellsIn cytoplasm of infected cells But in spotted fever-growth may take place in But in spotted fever-growth may take place in

nucleus as wellnucleus as well Rickettsiae grows better in cells that are not Rickettsiae grows better in cells that are not

metabolisingmetabolising Yolksac of chick embryos,hela,hep2,detroit6Yolksac of chick embryos,hela,hep2,detroit6 Tissue cultures not satisfactoryTissue cultures not satisfactory InoculationInoculation Propagated in arthopodsPropagated in arthopods

Antigenic structureAntigenic structure

Group and Species specific antigens Group and Species specific antigens Surface protein Antigens (SPA)-Surface protein Antigens (SPA)-

R.prowazekii &R.typhi-species R.prowazekii &R.typhi-species specific+cross reactive epitopesspecific+cross reactive epitopes

Outer Menmbrane Proteins(OMP)-A & B-Outer Menmbrane Proteins(OMP)-A & B-in spotted fever R.in spotted fever R.

A-adhesion species specificA-adhesion species specific Alkali stable polysaccharide SAnitigen-Alkali stable polysaccharide SAnitigen-

found in R.and proteus bacillifound in R.and proteus bacilli

Weil-Felix reactionWeil-Felix reaction -D/g of rickettsial -D/g of rickettsial infections by the demonstration of infections by the demonstration of agglutinins to proteus strainsagglutinins to proteus strains

P.vulgaris( P.vulgaris( OX 19,OX2,)OX 19,OX2,) P.mrabilis P.mrabilis (OX K)(OX K) Basis of the reaction is the sharing of Basis of the reaction is the sharing of

antigens between Rickettsia and proteusantigens between Rickettsia and proteus

Pathogenesis Pathogenesis

Arthopod bites and feces,minute Arthopod bites and feces,minute abberations by scratching----multiplies abberations by scratching----multiplies locally---blood----localised in vascular locally---blood----localised in vascular endothelial cells,which endothelial cells,which enlarges ,degenerates,---thrombus enlarges ,degenerates,---thrombus formation---partial/complete occlusion of formation---partial/complete occlusion of lumenlumen

It may survive in lymphoid tissues and It may survive in lymphoid tissues and other organs for yearsother organs for years

vaccinesvaccines

Weigl’s vaccine-phenolised intestinal Weigl’s vaccine-phenolised intestinal content of lice infected p.r. with content of lice infected p.r. with R.prowazekkiR.prowazekki

Castaneda-formalinised mouse-lung Castaneda-formalinised mouse-lung vaccinevaccine

Cox-inactivated yolk sac vaccineCox-inactivated yolk sac vaccine

Typhus fever groupTyphus fever group

IncludesIncludes

1.1. Epidemic typhus-R.prowezekiiEpidemic typhus-R.prowezekii

2.2. Recrudescent typhus/Brill Zinsser Recrudescent typhus/Brill Zinsser disease-latent form of abovedisease-latent form of above

3.3. Endemic typhus-R.typhiEndemic typhus-R.typhi

Epidemic typhusEpidemic typhus

Louse born typhusLouse born typhus Host –humansHost –humans Vector-body louse-Pediculus humanus Vector-body louse-Pediculus humanus

corporiscorporis Incubation period-5-15 daysIncubation period-5-15 days Fever ,chills,rashes-starting on trunks-Fever ,chills,rashes-starting on trunks-

spreading to limbs-sparing face palms and spreading to limbs-sparing face palms and soles.2soles.2ndnd week-stuporous,delirious week-stuporous,delirious

Endemic typhusEndemic typhus

Flee born typhusFlee born typhus Maintained in nature as a mild infection of Maintained in nature as a mild infection of

ratsrats Vector—Xenopsylla cheopis/rat fleaVector—Xenopsylla cheopis/rat flea Bite+ingestion of food contaminated with Bite+ingestion of food contaminated with

infected rat urineinfected rat urine Human infection is the dead endHuman infection is the dead end No man –man transferNo man –man transfer

R.typhi & R,prowazekii are closely similarR.typhi & R,prowazekii are closely similar To differentiate- To differentiate- Neill-Mooser/Tunica Neill-Mooser/Tunica

reaction reaction It is negative with prowazekiiIt is negative with prowazekii Infected blood of typhi---intra peritoneally--Infected blood of typhi---intra peritoneally--

male guinea pig--- fever and scrotal male guinea pig--- fever and scrotal inflammation-testis cannot be pushed back inflammation-testis cannot be pushed back to abdomen due to inflammatory to abdomen due to inflammatory adhesions between the layers of tunica adhesions between the layers of tunica vaginalisvaginalis

Spotted fever groupSpotted fever group

Common soluble antigen,multiplies in Common soluble antigen,multiplies in nucleus as well as cytoplasmnucleus as well as cytoplasm

Transmitted by ticks ,except R.akari-by Transmitted by ticks ,except R.akari-by mitesmites

Two typesTwo types

1.1. Tick typhusTick typhus

2.2. Rickettsial poxRickettsial pox

Tick typhusTick typhus R.rickettsii-Rocky moutain spotted fever-R.rickettsii-Rocky moutain spotted fever-

first insect transmitted bacterial pahogen first insect transmitted bacterial pahogen to be recognisedto be recognised

R.siberica-Siberian tick typhusR.siberica-Siberian tick typhus R.conori-indian tick typhusR.conori-indian tick typhus R.australis,japonica,africaeR.australis,japonica,africae

Transmitted transovarially in ticks-both Transmitted transovarially in ticks-both vectors & reservoirsvectors & reservoirs

Infection to any vertebrates hosts by any Infection to any vertebrates hosts by any of the larval stages/by adult ticksof the larval stages/by adult ticks

They invades the salivary glands—biteThey invades the salivary glands—bite

Rocky moutain spotted fever-transmitted Rocky moutain spotted fever-transmitted by tick by tick Dermacentor andersoniDermacentor andersoni

Rickettsial poxRickettsial pox

Mildest rickettsial d/sMildest rickettsial d/s Self limited,non fatal,Self limited,non fatal, Vesicular exanthemVesicular exanthem Also called vericelliform rickettsiosis- Also called vericelliform rickettsiosis-

similar to chicken poxsimilar to chicken pox Causitive agent is –R. akariCausitive agent is –R. akari Resevoiur- domestic mouse-Mus Resevoiur- domestic mouse-Mus

musculusmusculus Vector-mite-Liponyssoides sanguineus- in Vector-mite-Liponyssoides sanguineus- in

which transoverial transmission occurswhich transoverial transmission occurs

Genus orientia-Scrub typhus-Genus orientia-Scrub typhus-OXK +veOXK +ve

Chigger borne typhusChigger borne typhus Caused by orientia tsugutsugumushivector-Caused by orientia tsugutsugumushivector-

mites-belonging to the genus-Leptotrombidiummites-belonging to the genus-Leptotrombidium L.Lakamushi (japan)—L.deliensis (india)L.Lakamushi (japan)—L.deliensis (india) Mites inhibit sharply demarkated areas in the Mites inhibit sharply demarkated areas in the

soil- mite islandssoil- mite islands Mite larvae(chiggers) in island---bites human—Mite larvae(chiggers) in island---bites human— Mite feeds on warm blooded animals only in the Mite feeds on warm blooded animals only in the

larval stage and the adult form feeds only on larval stage and the adult form feeds only on plantsplants

Four factorsfor infection-Four factorsfor infection-O.tsu.,chiggars,rats,vegitationsO.tsu.,chiggars,rats,vegitations

Inc.p.-1-3 weeksInc.p.-1-3 weeks Eschar at thje site of bite,regional Eschar at thje site of bite,regional

lymphadenopathy,maculopapular rash.lymphadenopathy,maculopapular rash. d/s sets in with fever,head d/s sets in with fever,head

ache ,conjunctival congestion------ache ,conjunctival congestion------encephalitis and pneumoiaencephalitis and pneumoia

Three major antigenic types of O.tsu.-Three major antigenic types of O.tsu.-

1.1. KarpKarp

2.2. GilliamGilliam

3.3. katokato

Genus Genus –Ehrlichia/anaplasma/cowdria/neori–Ehrlichia/anaplasma/cowdria/neori

ckettsiackettsia

Seen in cytoplasm of the infected Seen in cytoplasm of the infected phagocytes-grows within phagocytes-grows within phagososmes-mulberry like clusters phagososmes-mulberry like clusters called morulacalled morula

Tick borneTick borne Three human d/sThree human d/s

1.1.Glandular fever like-E.sennetsu-lymphoid Glandular fever like-E.sennetsu-lymphoid hyperplasia & atypical lymphocytosis—by hyperplasia & atypical lymphocytosis—by ingestion of fish carrying infected flukesingestion of fish carrying infected flukes

2.2.Human monocytic ehrlichiosis-E.chaffeenis—Human monocytic ehrlichiosis-E.chaffeenis—amblyomma ticks—amblyomma ticks—lecopenia,thrombocytopenia,elevated liver lecopenia,thrombocytopenia,elevated liver enzymesenzymes

3.3.Human granulocytic Ehrlichiosis-E.equi—ixode Human granulocytic Ehrlichiosis-E.equi—ixode ticks—leucopenia,thrombocytopeniaticks—leucopenia,thrombocytopenia

T/t-DoxycyclineT/t-Doxycycline

Genus –Coxiella-Q feverGenus –Coxiella-Q fever

Coxiella burnetti—in group protobacteriaCoxiella burnetti—in group protobacteria Obligate intra-primarily affecting monocyte-Obligate intra-primarily affecting monocyte-

macrophage cellsmacrophage cells Bandicoot---ixodid ticks---domestic cattles----Bandicoot---ixodid ticks---domestic cattles----

human-occupation,milkhuman-occupation,milk Coxiela may enter thru abraded skin—Coxiela may enter thru abraded skin—

mucosa,lungs,intestinal tractmucosa,lungs,intestinal tract Iterstitial pneumonia,hepatitis,endocarditis,Iterstitial pneumonia,hepatitis,endocarditis, Spotaneous reovery is usualSpotaneous reovery is usual

Shows phase variation-1 and 2Shows phase variation-1 and 2 Fresh isolates-phase 1Fresh isolates-phase 1 On repeated passage thru yolk sac –phase 2On repeated passage thru yolk sac –phase 2 Reverts to phase 1 on passing thru guinea pigsReverts to phase 1 on passing thru guinea pigs Phase 1-a carbohydrate-per iodate sensitive-Phase 1-a carbohydrate-per iodate sensitive-

trichloro acetic acid solubletrichloro acetic acid soluble 1 are auto agglutinmable—phagocytosed in the 1 are auto agglutinmable—phagocytosed in the

absence of antibodiesabsence of antibodies 1 is more powerful immunogen1 is more powerful immunogen t/t Doxacyclinet/t Doxacycline

BartonellaBartonella

Gram –ve-transmitted by arthropods-Gram –ve-transmitted by arthropods-invade mammelian endothelial cells and invade mammelian endothelial cells and blood cellsblood cells

Human pathogenic formsHuman pathogenic forms

1.1. B.bacilliformisB.bacilliformis

2.2. B.quintanaB.quintana

3.3. B.henselaeB.henselae

B.bacilliformisB.bacilliformis

Oroya fevre/Carion’s disease-Oroya fevre/Carion’s disease-fever,progressive anaemia,bacterial fever,progressive anaemia,bacterial invasion of erythrocytes—mortality is high invasion of erythrocytes—mortality is high if untreatedif untreated

Verruga peruana-nodular ulcerating skin Verruga peruana-nodular ulcerating skin lesionlesion

Gram neg. rod—motileGram neg. rod—motileB.quintana-trench fever/5 day fever-not B.quintana-trench fever/5 day fever-not

fatal-by body lousefatal-by body louse

B.henselaeB.henselae

Febrile illness following Febrile illness following lymphadenopathy following a cat scratchlymphadenopathy following a cat scratch

Cat scratch diseaseCat scratch disease Also linked with two other conditions-Also linked with two other conditions-

seen commonly in hiv infected and seen commonly in hiv infected and immuno defficientimmuno defficient

1.1. Bacillary angiomatosis-vascular node Bacillary angiomatosis-vascular node /tumours in skin/tumours in skin

2.2. Bacillary peliosis-involves liver and Bacillary peliosis-involves liver and spleenspleen