Rickettsiae Flashcards
Physical description of Rickettsiae
- very small rods
- G negative
- obligate intracellular parasites
4 groups of Rickettsiae
Typhus, Spotted Fever, Ehrlichia/Anaplasma, Coxiella burnetti
types of Typhus group
R. prowazekii, R. typhi, R. akari, Orientalia tsut.
types of spotted fever group, and factor
R. rickettsii; and grows in cytoplasm
description of ehrlichia and anaplasma
- have chlamydia like life cycle(RB-EB alternation)
- monocytes: EHR
- granulocytes: ANA
- do not have PG or LPS
description of coxiella burnetti
- grow in host cell phagolysosome
- growth enhanced by sulfonamides; use of host cell adenine, folic acid synth. not required
Clinical presentation of typhus group
- parasite of blood vessel endothelium resulting in: vasculitis, rash
- begins on chest, spreads to extremities(no palm and soles)
- severe prostration, high fever
- epidemics associated with R. prowazekii
- mild associated with R typhii
- R.akari causes smallpox like rash
Clinical presentation of spotted fever group
- endothelial pathoge
- rash appears on extremities first, including palms and sole
- spread from extremities to trunk
Another name for spotted fever group and associated symptoms
- Rocky mountain spotted fever
- abrupt fever, headache, nausea, vomiting, muscle and join pain, abdominal pain
- pain due to vasculitis of organs
Clinical presentation of Ehrlichia chaffeensis
- headache, myalgia, thrombocytopenia, lymphopenia, bone marrow granulomas
- like RMSF, but usually no vasculitis
- obligate parasite of monocytes, macrophages
- pathology associated with immune response, esp. decrease of TNFalpha
Clinical presentation of Anaplasma phagocytophilum
- rash rare, but symptoms like ehrlichiosis
- obligate parasite of neutrophils and granulocytes
- pathology associated with immune response
Clinical presentation of Coxiella
- Q fever
- resembles influenza or pneumonia rather than typhus
- chronic infections lead to endocarditis
- granulomas of liver, spleen, bone marrow
- fever with pneumonia/hepatitis 2-3wks after exposure; typical
Epidemiology of Typhus group
- spread via human louse for R. prowazekii
- spread by rat flea for R. typhus; rodent host
- where or when hygiene is low
- live in humans as reservoir host and be transmitted
Epidemiology of spotted fever group
- spread by bite dog tick(EAST) or wood tick(Rockies)
- maintained in reservoir by transovarian cycle
- SE united states
Epidemiology of Ehrlichia and Anaplasma
- considered a zoonotic infection
- spread by ticks
- recent cases in WI, MN
