epidemic & endemic typhus Flashcards
taxonomy of epidemic & endemic typhus
caused by bacteria:
*epidemic typhus (lousy typhus)- Rickettsia prowazekii
*endemic typhus (rat typhus)- Rickettsia typhi
morphology
small, obligate, intracellular bacterium
-short rod
-gram negative
cultivation
- white mice
- chicken embryo
enzyme
Obligate intracellular parasites
antigens + virulence
*surface proteins: (Rickettsial Outer-Membrane Proteins - rOmp)
-rOmpA (adhesion)
-rOmpB (penetration)
*virulence:
- Pili & surface proteins – adhesion
- Phospholipase – penetration
- Cell wall LPS - has endotoxin properties
- Microcapsule – reactivation of bacteria
epidemiology of EPidemic typhus
source: sick person
vector: body&head louse
trans method: contact with infected body-louse or their feaces
(contact)
gate: damaged skin
epidemiology of ENdemic typhus
source: rodents
vector: rat fleas & rat ticks
tran.method: from bites and feaces of infected fleas
(bites & contact)
gate: damaged skin
Clinical manifestations
- sharp headache & insomnia
- red puffy face & eyes
- body rash
pathogenesis
- pili &surface proteins-adhesin to target cell
- phospholipase for CM penetration
- rickettsia penetrates through defects of CM
- replicates in cytoplasm
lab diagnosis
- microscopic exam
- serodiagnostics by ELISA
TREATMENT
Tetracycline antibiotics.
prophylaxis
typhus vaccine for epidemic strain
not endemic typhus
