Vector-Borne Transmission Flashcards
Describe the structure of Borrelia
Long spirochete
0.4uM (big enough for light microscope)
Stain G-, but NO LPS
Inflamm. lipoproteins in outer membrane
Four indicators of sepsis?
Hypotension
Fever
Heightened HR/BR
Infection Signs
Clinical Presentation of Borrelia recurrentis, hermsii, and 20 others
Bacteremia within week of inoculation
Fever, Intense Headache, Muscle Pain for 3-5 days
Symptoms Recurr after 5-10 days latency
May eventually form necrotic foci at parenchymatous organs
Why does Borrelia recurrentis keep on coming back?
Antigenic variation (may go through 5-10 cycles)
Borrelia burgdorferi (and 9 others in Eurpose) cause…
Lyme Disease
Symptoms of Lyme Disease?
Early – Flu-like, Bull’s Eye Rash
Early Disseminated – Facial Nerve Palsy, Meningitis, Carditis
Chronic – Arthritis, Joint Pain, Affect Heart/Nerves
Classy name for Bull’s Eye Rash?
Erythema chronicum migrans
How is Borrelia recurrentis spread?
Human Louse
How is Borrelia hermsii spread?
Soft bodied ticks with a rodent reservoir
– Transovarian and through bite
How is Borrelia burgdorferi spread?
Deer tick nymph with deer, mouse, or bird reservoir
Pathogenesis of Borrelia recurrentis and hermsii
Uses VMP (variable major protein) antigen Mostly the same, with a few mutants Abs select for the mutants
What leads to Borrelia recurrentis latency? relapse?
Latency – Most of the population killed
Relapse – Mutant variety grows to repopulate
Pathogenesis of Borrelia burgdorferi
Multiple rounds of symptoms probably means multiple infections with difference burgdorferi strains
How is Borrelia controlled?
- Avoid Vectors
- No effective vaccine
How is Borrelia treated?
Doxycycline or synthetic penicillins
can use 3rd gen cephalosporins
Describe the structure of Rickettsiae
Small G- Rods
Growth conditions required for Rickettsiae?
Obligate intracellular parasite
How is Rickettsiae cultured?
Yolk sac of embryonated egg
Four groups of Rickettsiae?
Typhus group
Spotted Fever Group
Enlichia, Anaplasma
Coxiella burnetti
Which of the four Rickettsiae groups isn’t really a Rickettsiae, but is likely classified that way according to our shelf materials
Coxiella burnetti
Who is in the Rickettsiae Typhus group?
Where do they grow?
prowazekii, typhi, akari
Cytoplasm of Host Cell
Who is in the Rickettsiae Spotted Fever group?
Where do they grow?
rickettsii
Cytoplasm of host cell
Describe the lifecycle of Rickettsiae ehrlichia, anaplasma.
Chlamydia-like (RB-EB alternation) in monocytes (Ehr) or granulocytes (Ana)
What is structurally unique about Rickettsiae ehrlichia, anaplasma
NO PG or LPS
Where do Coxiella burnetti grow?
Host cell phagolysosome
What should you never treat coxiella burnetti with?
Sulfonamides – they enhance the growth
Clinical presentation of Rickettsiae Typhus group?
Parasite of BV endothelium
Vasculitis, Rash (Chest–>Extremities)
Weakness, Fever
Clinical presentation of Rickettsiae Spotted Fever group?
Rash from extremities (Palms and Soles) –> Trunk
Rocky Mountain Spotted Fever
What does Rocky Mountain Spotted Fever entail?
Abrupt fever, headache, nausea, vomiting
Muscle, Joint, Ab pains from vasculitis of organs
50% fatal untreated
Clinical presentation of Rickettsiae Ehrlichia chaffeensis (monocytic erlyichiosis, HME)
Headache, Myalgia, Thrombocytopenia, lymphopenia, Marrow Granuloma
Like RMSF< but no vasculitis
What cells does Rickettsiae ehrlichia chaffeensis infect?
Monocytes/Macrophages
What tends to cause the primary pathology of Rickettsiae ehrlichia chaffeensis?
Immune Response
Decrease in TNF-a early, Increase late
Clinical presentation of Rickettsiae anaplasma phagocytophilum?
Rarely rash, but otherwise like ehrlichosis
What cells does Rickettsiae anaplasma phagocytophilum infect?
Neutrophils and Granulocytes
Other name for Coxiella burnetti
Q-Fever
Clinical presentation of Coxiella burnetti?
Typically: Fever w/ Pneumonia/Hepatitis 2-3 week post exposure
Can be:
- Chronic infections leading to endocarditis in pts w/ defective heart valves
- Granulomas in liver, spleen, BM
How is Rickettsiae Typhus Group spread?
Human Louse or Rat Flea
Transmit Human-Louse-Human
Rats are also reservoir
Where is Rickettsiae Typhus Group typically seen?
People together with low hygiene.
POWs, refugees
How is Rickettsiae-Spotted Fever Group spread?
Bite of Dog-tick or Wood-tick
How is Rickettsiae-Spotted Fever group maintained in reservoir?
Transovarian cycle
What part of the country is most prone to dvelop Rickettsiae-Spotted Fever group? What time of year?
Southeast US
Summer, Fall
How is Rickettsiae-Ehrlichia/Anaplasma spread?
Where is it commonly found?
Ticks.
WI, MN
How is Coxiella burnetti spread to humans?
Via dust or aerosols from infected animals
Especially in placental aerosols
Common carriers of Coxiella burnetti include…
Goats
Cattle
Sheep
Cats
Pathogenesis of Rickettsial diseases?
Arthropod bite site –> Endothelium
Multiply Intracellularly and Spread to other tissues
Phospholipase A targets Cell Membranes
What does Rickettsiae phospholipase A do?
Lyses blood vessels (rash) and other epithelial cells
How does R. Rickettsii one up the norman Rickettsiae vessel lysis?
It lyses smooth muscle cells
How are Rickettsial diseases controlled?
Remove Vector Contact
Vaccine for Q-fever (only in Australia)
How are Ricketsial diseases treated?
Tetracycline/Doxycycline
