RICKETTSIACEAE Flashbackkkkk - PowerPoint Presentation

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RICKETTSIACEAE

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Flashbackkkkk………..

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RICKETTSIACEAE

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General features

Gram negative bacilli

Obligate intracellular parasitism

Primarily infect arthropods

Transmitted to humans by vectorsIn humans infect vascular endotheliumHoward Taylor Ricketts 1906Genera-

Rickettsia, Orientia

,

Ehrlichia

(

Coxiella

,

Rochalimaea

)

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General features contd…..

Pleomorphic

coccobacilli

0.3-0.6by 0.8-2 micron in sizeGram stain not very useful, stain light(G –ve

)Giemsa, Casteneda- bluish purple

Machiavello

,

Giminez

- deep red

Do not grow in culture media.

Yolk sac of chick embryo,

HeLa

and Hep-2 cell lines- primary isolation

Animal inoculation- Guinea pigs, Mice

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Replication

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Classification

Genus

Rickettsia

- 2 groups of diseases : TUPHUS FEVER, SPOTTED FEVER

Genus Orientia

– Scrub typhusGenus Ehrlichia

-

Ehrlichiosis

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GROUP

SPECIES

DISEASE

VECTOR

VERTEBRATE RESERVOIR

DISTRIBUTION

TYPHUS

R.

prowazekii

Epidemic typhus

Louse

Humans

Worldwide

R.

typhi

Endemic typhus

Rat flea

Rats

Worldwide

SPOTTED FEVER

R.

rickettsii

Rocky Mountain Spotted Fever

Tick

Rodents

North America

R.

conori

(R.

siberica

,

R.

japonca

)

Indian Tick Typhus

Tick

Rodents

India

R.akari

Rickettsial

pox

Mite

Rodents

USA, Russia

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Others

DISEASES

RICKETTSIAL AGENT

INSECT VECTOR

MAMMALIAN RESERVOIR

a) Q fever

C.

burnetti

Nil

Cattle,

sheep,goats

b) Trench fever

Rochalimaea

quintana

Louse

Human

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Napoleon Wasn’t Defeated by the Russians

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NEWS

The lice that almost defeated socialism

Posted by

stalinsmoustache under 

Lenin, odd animals, socialism

 | Tags:civil war, 

fuel

, 

grain

, 

lice

, 

reading Lenin

, 

war communism

 | 

Comrades, we must concentrate everything on this problem. 

Either the lice will defeat socialism, or socialism will defeat the lice!

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Epidemic typhus

Worldwide but common in Russia and East Europe.

1917-1922-

Napolean

retreat

25 million cases & 3

mil.deaths

Socialism Vs Louse

Von

Prowazek

Humans- the only natural vertebrate host

Vector-

Pediculus

humanus

corporis

Incubation period: 5-15 days

Clinical features: fever with chills, skin rash 4

th

- 5

th

day(trunk-limbs sparing face, palm, soles); 2

nd

wk-stupor, delirium.

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Pathogenesis of typhus fever

Source of infection: Infected patient

Mode of infection: Body louse feces rubbed onto abrasions on skin.

Louse feeds on infected patient

Rickettsiae multiply in GIT of the insect & appear in feces in 3-5 days.

Louse may be transferred to another person Lice defecate while feeding and when louse feces is rubbed through minute abrasions caused by scratching.( aerosol inhalation/ conjunctiva- dried louse feces)

Rickettsemia.

TYPHUS= dhupa (Sanskrit)/ typhos(cloud).

CFR= 40%

Recovery-? Latency in lymphoid tissue ----Recrudescent typhus

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Brill-Zinsser disease

Reactivation of latent/dormant R.

prowazekii

Rickettsiae can remain without louse as reservoir.

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Endemic typhus ----R.typhi

/R.

mooseri

Fleaborne

typhusVector-

Xenopsylla cheopis

Humans acquire through - Bite of infected flea

Mild disease

No man to man transmission

Worldwide- KASHMIR in India.

Neill

Mooser

reaction-

Tunica reaction to differentiate epidemic from endemic typhus.

Male guinea pigs –

intraperitoneal

inoculation with blood from

rickettsemic

patient- inflammatory adhesions between the layers of tunica

vaginalis

- testes cannot be pushed into the abdomen.

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Tick Typhus

Rocky mountain spotted fever

Siberian tick typhus

Indian tick typhus

R. rickettsii

- the first insect transmitted bacterial pathogen to be recognisedTransovarially

transmitted in ticks(reservoirs)

RMSF-

Dermacentor

andersoni

, Most serious spotted fever

North and South America

Boutonneuse

fever in the

mediterranean

-

Conor

India - Himalayas –

Megaw

1917

Ripicephalus

sanguineus

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SCRUB TYPHUS

Orientia

tsutsugamushiEast Asia, Korea to Indonesia, Australia

Mite larvae (chiggers)Zoonotic tetrad (Agent. Chiggers, rats, vegetation )Tsutsuga= dangerous

Mushi= mite

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Ehrlichia

Affinity to blood cells

Mulberry like clusters (

morula ) inside the infected cellAnaplasma

/ CowdriaTick borne infections of cattle and sheep

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Types of Ehrlichiosis

E.

sennetsu

– Sennetsu fever ( lymphoid hyperplasia

E. chaffeensis – Human monocytic

ehrlichiosisE. equi - Human granulocytic ehrlichiosis

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Diagnosis

Microscopy

Serological

Tests

(Weil-Felix reaction, ELISA, IF,

– Paired sera to be tested.

Molecular methods – PCR.

Isolation of

Rickettsiae

–

HeLa

, Vero cell lines,

Chick embryo

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WEIL FELIX TEST

Disease

Antigen

OX19

OX2

OXK

Epidemic

typhus

+++

+

_

Brill Zinsser disease

+

_

+

_

_

Endemic typhus

+++

+

-

_

Spotted fever

++

++

_

Scrub typhus

_

-

+++

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Coxiella

burnetii

Coxiella burnetti is the causative agent of ‘

Q-fever’

Obligate intracellular, gram negative bacterium

D

istributed globally

Found in many species of animals

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Morphology

obligate intracellular pathogen .

gram negative .

Pleomorphic .

size : rods:- 0.2 – 0.4 x 0.4 – 1.0 mc

spheres :- 0.3 – 0.4 mc

filterable .

better stained with GIMINEZ and other rickettsiael stains .

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Culture

Grows well in yolk sac of chick embryos and in various cell cultures .

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Resistance

Resistant to physical and chemical agents

In pasteurization flash method is effective

Can survive in dust and aerosols

Inactivated by 2% formaldehyde

5% H

2

O

2

1% Lysol .

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Contd….

Resistant to heat, drying and disinfectants

Air samples test positive for 2+ weeks

Soil samples test positive for 150+ days

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History

A ZOONOTIC DISEASE

Q stands for

Q

uery or

Q

ueensland

Origin of disease unknown

First reported cases were in Queensland, Australia

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Differentiating features

from

Rickettsiae

:

1. Having smaller size

2. Resistance to heat and drying

3. Major route of transmission is-

inhalation/ingestion

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Primary

Reservoir -? Bandicoots

Cattle

Sheep

Goats

* All eukaryotes can be

infected TICKS

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Bacteria is excreted in:

Feces

Urine

Milk

of infected animals

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Release Into Environment:-

D

uring birthing the organisms are shed in high numbers

in amniotic fluids and the placenta

109 bacteria per gram of placenta

Do not touch!

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Transmission

Most common route is inhalation of

aerosols

Consumption of raw

Contaminated dust, manure, birthing products

Tick bites (rare)

Human to human also very rare

gsbs.utmb.edu

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Center for Food Security and Public Health Iowa State University - 2004

Transmission

Person-to-person (rare)

Transplacental (congenital)

Blood transfusionsBone marrow transplantsIntradermal inoculationPossibly sexually transmitted

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Who’s at risk?

Farmers

, veterinarians, researchers, abattoir (slaughterhouse) workers etc.

People who breed animals

Immunocompromised

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*Bacteria spread through blood

gsbs.utmb.edu

Acute or Chronic Q fever

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Acute Q fever

Symptoms :

Asymptomatic

Self-limiting

, flu-like disease

Fever, nausea, headaches, vomiting, chest/abdominal pain

Pneumonia &

granulomatous

hepatitis

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Chronic

Q fever (> 6 months)

Endocarditis

&

meningoencephalitis

Hepatitis

Spontaneous recovery

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complications

Bacteria may remain latent in tissues for 2-3 years

HepatitisEndocarditis

Cirrhosis

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Host interaction

Entry via inhalation

Alveolar macrophages encounter bacteria

C. burnetii phagocytosed

Macrophage

C. burnetii

R Heinzen, NIAID

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Host interaction

Replication within

phagolysosme

Low pH needed for metabolism

No cellular damage unless

lysis

occurs

Can invade deeper tissue and cause complications

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Phagocytosis

Binding/entry into macrophages via:

I

ntegrin

A

ssociated

P

rotein (IAP)

L

eukocyte

R

esponse

I

ntegrin (LRI

)

macrophage

bacteria

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Lysis of phago-lysosome and macrophage

Phago-lysosome fusion: bacteria survive and multiplies

Phagocytic vesicle

Phagocytosis

Binding & Entry

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LAB DIAGNOSIS

Hard to diagnose because

:

Asymptomatic in most cases

Looks like other disease (Flu or cold)

Serology continues to be best method

PCR, ELISA and other methods

WEIL – FELIX test is negative .

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Contd…..

Bio safety level 3 (BSL-3) facility

Very infectious (one organism causes infection)

Listed by the CDC as a potential bioterrorism agent.

Isolated in cell cultures or embryonated eggs

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Treatment

Once infected, humans can have life-long immunity

Acute Q fever treated with:

doxycycline

,

chloramphenicol

,

erythromycin or

fluoroquinolones

Chronic Q fever treated with:

More

than one antibiotic

tetracycline

and

cotrimoxazole

for 2 years

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Vaccines

:-

prepared from formalin killed whole cells

attenuated strains

trichloroacetic

acid

extracts

NOT FOR GENERAL USE.

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Prophylaxis:-

Pasteurization and sterilization of milk and other dairy products

Disinfect utensils, machines used in farm areas for birthing

Regular testing of animals and those who work closely with them

Protective Personal Equipment

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BARTONELLA

Family

Bartonellaceae

contain two genera

Bartonella

Grahamella

Grahamella

does not infect humans

Bartonella

contain 3 species:

B.bacilliformis

B.quintana

B.henselae

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BARTONELLA BACILLEFORMIS

Carrions

disease

Daniel Carrion – Peru

OROYA fever

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PATHOGENISIS:-

Causes OROYA fever

Transmitted by SAND

flies

Infects RBCs

INCUBATION PERIOD;

3 weeks to 3 months

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CLINICAL FEATURES

:-

Fever

Headache

Chills

Severe anemia

Several weeks after recovery pt. develop

nodular lesions on the body

Secondarily infect produce ulcers –

VERUGA PERUANA

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Lab diagnosis:-

Demonstrated in blood smear by GIEMSA stain

Seen in cytoplasm and adhere to cell surface

Grown on NA agar contain rabbit serum

,

Hb

Guinea pig inoculation leads to

VERUGA PERUANA

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TRETMENT & PREVENTION

Susceptible to penicillin

streptomycin

Tetracycline

Chloramphenicol

Insecticides such as DDT should be used

to eliminate sand flies

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BARTONELLA QUINTANA

Formerly called Rochalimaea quintana

Causes TRENCH fever

also called FIVE DAY fever

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Transmission; by body

louse

No animal reservoir

vertical transmission does not occur in lice

Lice

after acquiring infection remain infectious through out life

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CLINICAL FEATURES:-

Mild symptoms

leads to chronic

bacteremia

Relapse have been observed even after 20 years primary disease

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Rick

quintana

Rochalimaea

quintana ( da Rocha Lima )

Bartonella quintana

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Lab diagnosis:-

Detected in the gut of infected lice

Isolate from pt. blood by

culture

sheep blood agar

Weil-

felix

test negative

PCR- detect organism in tissues

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Still exists ????

World wars

Recently Tunisia and Mexico

USA

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BARTONELLA HENSELAE

Causes CAT-SCRATCH disease

Occur by contact with scratch / bite of

an infected cat

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Cat contact

(scratch, bite,

? cat flea bite)

1 -

3

weeks

Resolution

in weeks to

months

Dissemination

in immuno-

compromised

hosts

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CLINICAL FEATURES:-

Regional

lymphadenopathy

Fever

Endocarditis

In AIDS pt. leads to;

bacillary

angiomatosis

(

vascular

nodules/

tumours

appear on skin, mucosa etc

)

bacillary

peliosis

(

liver and

spleen)

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Lab diagnosis:-

lymph node biopsy – stained with

WARTIN-STARRY SILVER IMPREGNATION –clusters of bacillus

Grow on chocolate agar/ columbia agar

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TREATMENT:-

Self limiting

No specific treatment required