Zoonotic infxns Flashcards
Stable rodent-flea infxn cycle that is maintained in a resistant host population w/o excessive host mortality
(long term reservoir of infxn)
Enzootic plague
Plague bacilli are introduced into rodent or small mammal populations that are moderately or highly susceptible to lethal effects of the infxn
epizootic plague
PLague that results in lymph gland swelling resulting from bite of flea 2-5 days earlier
(60-90% mortality if untreated)
bubonic plague
- most common form of plague
primary or secondary lung infxn which is highly infectious and 100% fatal if untreated
pneumonic plague
Type of plague that results in invasion of almost all organs, no sig evidence of prior disease
- death occurs in 12-24 hrs
- can see ecchymosis
septicemic
stain seen with yersinia
giemsa stain: see bipolar “safety pin”
Virulence of yersinia pestis
- plasmic encoded factors
Type III secreted proteins:
- tyrosine phosphatase
- cytotoxic factors
VW surface antigens
Flea associated virulence factors
Coagulase fibrinolysin
Yersinia pestis virulence
- chromosomally encoded
- iron acquisition systems
- attachment and invasion factors
- endotoxin
Phase variation
ability to change protein on its surface
- immune system can no longer recognize it
Francisella tularensis can do that
Which can be spread person to person?
Yersinia or Francisella?
Yersinia only
- no need to isolate indiv w/ francisella
How many % of Ixodes deer tick carry borrelia burgdorferi?
10-36%
- most of these ticks associated with lyme diseases are assoc. with the nymphal stage bite
When do the ticks mainly infect humans?
Late spring and summer in their 2nd year of life
Reservoir for lyme disease (borrelia burg)
mouse
White tailed deer
Where are the ticks for lyme disease endemic to?
Northeastern US
Vector for rickettsial diseases
- Rickettsia rickettsii
- Prowazekii
- Typhi
- Rickettsia rickettsii: ticks
- Prowazekii: lice
- Typhi: fleas
can lay 8 nits (eggs)/day
Stain used to stain rickettsiae?
Giema stain
Where do rickettsia invade?
endothelial cells and disseminate throughout vascular system
Which rickettsial disease starts at wrist and ankle and spreads to trunk and palms?
Which starts centally and spreads out?
Rockey mountain spotted fever:
- starts at wrist and ankle and spreads to trunk and palms
Typhus:
- starts centally and spreads out
Which organisms are found in south atlantic states (North carolina, oklahoma, TN?)
Rocky mt spotted fever
- also the most frequently reported rickettsial illness in US
virulence of anaplasmosis and erlichia
- Enters via lipid rafts
- Prevents phagosome fusion with lysosome
- downregulates ROS generation
- Inhibits host cell apoptosis
Vector for:
Erlichiosis
Anaplasmosis
Q fever
Erlichiosis: tick
Anaplasmosis: tick
Q fever: no arthropod vector - inhaled spores from cattle/sheep
YOPS
tyrosine phosphatase
Secreted protein that subverts nl activation mechanism of phagocytic cells
Virulent strains of F. tularensis requires what for growth?
cysteine
is cellular or humoral immunity required for F. tularensis required for recovery?
Peak incidence?
Cellular immunity
Summer (ticks)
Winter (hunting)
Scrub typhus
- etiologic agent
- common reservoirs
- modes of transmission
Scrub typhus
- Orientia tsutsugamushi
reservoir: Chiggers (larval mites) - Chigger mite bite –> eschar
- rash absent
Classic triad of rocky mt spotted fever
- HA
- Fever
- Rash (petechial lesions)
Brills disease
- etiologic agent
- common reservoirs
- modes of transmission
Rickettsia prowazekii
- no rash
- occurs many yrs after primary infxn
*prowazekii also cause epidemic typhus which does cause rash
Host cells of rickettsiae are endothelial cells, what are the target cells of erlichia and anaplasma?
Phagocytic cells
- multiply in phagosome instead of cytosol
Erlichiosis: infects monocytes and macrophages
Anaplasmosis:
infects neutrophils
Geographical location of erlichia and anaplasma?
erlichia: South central and south eastern US
anaplasma: Northeast and upper midwest US
