Rickettsiae

Question 1

Physical description of Rickettsiae

Answer 1

• very small rods
• G negative
• obligate intracellular parasites

Question 2

4 groups of Rickettsiae

Answer 2

Typhus, Spotted Fever, Ehrlichia/Anaplasma, Coxiella burnetti

Question 3

types of Typhus group

Answer 3

R. prowazekii, R. typhi, R. akari, Orientalia tsut.

Question 4

types of spotted fever group, and factor

Answer 4

R. rickettsii; and grows in cytoplasm

Question 5

description of ehrlichia and anaplasma

Answer 5

• have chlamydia like life cycle(RB-EB alternation)
• monocytes: EHR
• granulocytes: ANA
• do not have PG or LPS

Question 6

description of coxiella burnetti

Answer 6

• grow in host cell phagolysosome

- growth enhanced by sulfonamides; use of host cell adenine, folic acid synth. not required

Question 7

Clinical presentation of typhus group

Answer 7

• 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

Question 8

Clinical presentation of spotted fever group

Answer 8

• endothelial pathoge
• rash appears on extremities first, including palms and sole
• spread from extremities to trunk

Question 9

Another name for spotted fever group and associated symptoms

Answer 9

• Rocky mountain spotted fever
• abrupt fever, headache, nausea, vomiting, muscle and join pain, abdominal pain
• pain due to vasculitis of organs

Question 10

Clinical presentation of Ehrlichia chaffeensis

Answer 10

• 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

Question 11

Clinical presentation of Anaplasma phagocytophilum

Answer 11

• rash rare, but symptoms like ehrlichiosis
• obligate parasite of neutrophils and granulocytes
• pathology associated with immune response

Question 12

Clinical presentation of Coxiella

Answer 12

• 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

Question 13

Epidemiology of Typhus group

Answer 13

• 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

Question 14

Epidemiology of spotted fever group

Answer 14

• spread by bite dog tick(EAST) or wood tick(Rockies)
• maintained in reservoir by transovarian cycle
• SE united states

Question 15

Epidemiology of Ehrlichia and Anaplasma

Answer 15

• considered a zoonotic infection
• spread by ticks
• recent cases in WI, MN

Question 16

Epidemiology of coxiella burnetii

Answer 16

• spread to animals via ticks
• humans via dust or aerosols from infected animals
• goat, sheep, cattle, cat
• placental aerosols, occupational hazard

Question 17

Pathogenesis of Borrielia

Answer 17

• highly pathogenic, infectious dose 1 cell
• spread from arthropod bite site in bloodstream to infect endothelial cells
• C. burnetti infects lung epithelia
• multiply intracellularly and spread to other tissues
• phospholipase A targets cell membranes
• lyses blood vessels(rash) and other epithelial cells
• R.rickettsia also lyses smooth muscle cells

Question 18

Read the images of the ppt

Answer 18

Read the images of the ppt

Question 19

Control of borrelia

Answer 19

• remove vector contact
• rat control, tick control
• tetracycline/doxycycline