Rickettsia Flashcards
Rickettsia and Orientia
RICKETTSIA = RASH
Epidemiology: Obligate intracellular
Epidemiology: Transfered via arthropod vectors (fleas, lice, mites, ticks). Seasonality of this bacteria is dependent on the vector of on which it resides. Humans do not propagate the disease (unless the bacteria is Rickettsia prowazekii, in which case humans spread is predominantly). They need host to survive. Small genomes (reduced to rely on host for AA and nucleotides. Has cell transport system to intake from host. Also, closely related to bacteria than other bacteria), but the genomes are larger than mycoplasma.
Lab testing: PCR and serology, but difficult
clinical manifestation: Rash (and fever/headache)
Rickettsia typhi
Typhus and spotted fever!!!
Roams free in the cytoplasm, unlike chlamydia which stays in inclusion bodies.
Ehrlichia chaffeensis
MORULA!!!!
Coxiella burnetii
Epidemiolgy: Spread via sheep, goats, cattle
Rickettsia rickettsii
ROCKY MOUNTAIN SPOTTED FEVER (in Montana and rocky mountains, among other states)
epidemiolgy: SPREADS VIA DOG TICKS (Dermacentor variabilis). 25% fatality rate. Difficult to diagnose since symptoms take 2-4 days after infection.
Pathogenesis: Bacteria attaches to outer protein membrane OmpA or OmpB. Phagocytosed. Escapes from phagosome and enters cytosol. Proliferates, leading to cell damage and increased permability of the vasculature. Uses host cell to conduct actin mediated propulsion. Does not destroy initial cell. Petechial rash = result of the network of cells the bacteria has invaded.
Clinical manifestation: fever, headache, rash (petechial) begins around wrist
and ankles and spreads toward trunk!!! rickettsialpox
eschars
Treatment: Fatal
Rickettsia prowazekii
Epidemiology: Not related to typhoid fever. The only Rickettsia capable of causing an epidemic. major killer after WWI. Major killer in WWII too. Prevalent in wars/floods. Homeless communities. Transferred through infected lice. Replicates till cells of lice burst. Feces of the lice infect the host human upon landing. FLYING SQUIRRLE + MAJOR Reservoire IN US!!! 100% of the lice die after they infect a human, but the lice done dye upon infecting the flying squirrel.
Treatment: Spray DTT all over clothes and skin. Vaccine
Clinical manifestation: severe headache, fever, myalgia, rash from trunk to extremities. Brill-Zinsser = recrudescent form of lice-borne typhus. Note: Categorized as bioterrorism weapon.
Rickettsia typhi
MURINE TYPHUS
epidemiology: tropical/subtropics. Lives in rats. Developing countries had it more prominent in rat flea. Rat to rat transmission. Flea feces could spread to human if fleas was infected.
Clinical manifestation: systemic endothelial indection. Milder Rocky Mountain spotted fever (RMSF)
Orientia tsutsugamushi
Scrub typhus
epidemiolgy: chigger mice. Transferred via ovaries of females.
Ehrlichia and Anaplasma
Epidemiolgy: tick borne illness. Infection specifically through monocytes/macrophages (Ehrlichia) and neutraphils (Anaplasma). Have 2 cores (Morula) of two different sizes, located in cytoplasmic membrane. Thin cell walls since they lack peptidoglycan and LPS
Human Monocytic Ehrlichiosis (HME) and Ehrlichia chaffeensis
Epidemiology: May through august, Dog tick, Lone Star tick, white tailed deer spreads it, southeastern US.
Clinical symptoms: fever, LEUKOPENIA, thrombocytopenia
Human Granulocytic Anaplasmosis (HGA) and Anaplasma phagocytophilum
Lxodes scapularis is the tick of choice. Same tick as Lyme disease tick. Found in southern new england, nj, ny, mn, wi.. Major reservoir = white footed mouse.. Lives predominantly in neutraphils.
Clinical features: morulae in 20-80% of the patients. fever, headache, MYALGIA. rash is rare.
