Title: Rickettsia
1Rickettsia
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2Howard Ricketts
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- (Rickettsia)
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Reckettsiales
3Common characters
- Obligated intracellular parasites
- Related to arthropod vector.
- Zoonosis.
4Morphology stains
- Arranged irregularly
- polymorphism
- Small G- bacilli
- Giemsa stain violet or blue
5Cultural properties
- Binary fission
- Have both DNA and RNA
- Culture susceptible animal (guinea pig), yolksac
of chick embryo, cell culture.
6Resistance
- weak, sensitive to antibiotic
- Survive in low temperature and dry condition
- Sulfanilamide can stimulate reckettsias
proliferation
7 Antigenic sturcture
- Group specific antigen
- Endotoxin similarly to endotoxin of bacteria
- Specy specific antigen
- membrane protein
- Weil-Felix reaction(????)
- Detect anti-rickettsial antibodies in a
patients serum by agglutination of the proteus
organisms. ( rickettsia posses Ag that
cross-react with Ab of the O antigen of certain
proteus)
8Pathogenic mechanism
Endotoxin ? Phospholipase A
Pathogenic material
Bite or feces of arthropod vector
Local( small blood vessels in lymphoid
tissue )
Pathogenic mechanism
(First bacteremia)
vascular endothelial cells
(Second bacteremia)
Fever, headache, rash
Pathogenic sites
vessels
9Pathogenicity
- Pathogenic materials
- Endotoxin similarly to endotoxin of bacteria
- Phospholipase A lysis the cell membrane and
lysosome membrane of the host cell, causing
hemolysis - Pathogenic mechanism invade the epithelial cells
of small blood vessule
10Pathogenic mechanism
Endotoxin ? Phospholipase A
Pathogenic material
Bite or feces of arthropod vector
Local( small blood vessels in lymphoid
tissue )
Pathogenic mechanism
(First bacteremia)
vascular endothelial cells
(Second bacteremia)
Fever, headache, rash
Pathogenic sites
vessels
11Infective route
- SourceRickettsiae normally enter the body
(mammalian reservoir) through the bite or feces
of an infected arthropod vector.-----arthropod
vector mite, tifck, louse, flea - Pathogenic mechanism invade the epithelial cells
of small blood vessule
12Pathogenic mechanism
Endotoxin ? Phospholipase A
Pathogenic material
Bite or feces of arthropod vector
Local( small blood vessels in lymphoid
tissue )
Pathogenic mechanism
(First bacteremia)
vascular endothelial cells
(Second bacteremia)
Fever, headache, rash
Pathogenic sites
vessels
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15Epidemic typhus (R.prowazekii)??????
- Louse-borne substandard living condition, poor
sanitaion overwhelming bacterimia -
Human
Human louse
Human louse
Human
16Epidemic typhus (R.prowazekii)??????
- Fever (temperature rises to 40ÂșC
- Treatment sanitation, eradication of human lice
vaccine, tetracycline
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18Endemic typhus (R. mooseri)????????
human louse
rat
rat flea
rat louse
human
human
rat flea
human louse
rat
feverheadackmaculopapular rash
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20Immunity
- Mainly depends on CMI
- Strong immunity after recovery
21Microbiological examination
- Specimen blood
- Isolation and culture guinea pig
- Serological test Weil-Felix reaction
22Principle of prevention and treatment
- Control and eradicate its intermediate
- host and reservoir host
- SpecificityRat lung vaccine(???????)
Prevention
Treatment
 Chloramphenicol(???) Tetracycline(???) Ban-Sulfa
drugs(??????)
23Thank you!