Zoonoses I Flashcards
Which virulence factor of Borrelia burgdorferi:
1) Primes PMNs to release granules and superoxides that cause joint pain (infectious arthritis - a hallmark of Lyme disease)
2) Converts plasminogen to plasmin, digesting the ECM, helping in the spread of the organism
OspA
T/F Strains of Borrelia burgdorferi with the OspB are more invasive than mutants lacking it.
TRUE
Borrelia burgdorferi OspB is used for serodiagnosis with _____
Western Blot
The vector of Borrelia burgdorferi/Lyme disease is the _____. How is the organism introduced?
Ixodes tick
Introduced via tick saliva and vomit
T/F Removal of a tick within 24 hours may stop the transmission of Borrelia burgdorferi.
TRUE
In the first stage of Lyme disease, patients demonstrate flu-like symptoms and pathognomonic _____.
Erythema chronicum migrans aka “Bull’s eye rash”
What symptoms characterize the second stage of Lyme disease? Where is the organism at this point? What mediates this stage of the disease?
Sx: Acute arthritis, cardiac disease, meningitis, & Bell’s Palsy (more severe cases) - Appear weeks to months after bite.
The organism may be systemic or even dead at this point
The second stage of Lyme disease is mediated by the host inflammatory response.
What three symptoms characterize the third stage of Lyme disease?
1) Chronic arthritis
2) Chronic skin lesions
3) Chronic neurological problems
These appear months to years after the tick bite
The third stage of Lyme disease is thought to be _____ in nature.
Autoimmune
T/F serologic evaluation of CSF, blood, or synovial fluid for B. burgdorferi can be done at any stage of the disease
FALSE
Must be early on in the infection
_____ is used to look for B. burgdorferi DNA in tick (peel it off the patient) or host tissue.
PCR
Lagniappe: Immunostaining of biopsy sample may also be used to detect the bacteria
What are the four treatment options for Lyme disease?
1) Doxycycline
2) Beta-lactams
3) Tetracyclines
4) Erythromycin
What role does Borrelia recurrentis’ virulence factor VMP play?
It is a surface protein that varies antigenic epitopes in response to immune clearance.
The relapsing nature of Borrelia recurrentis infection is attributable to _____
Modifications by VMP (gene activated by gene conversion)
Borrelia recurrentis is carried by _____ and _____
Human body lice and ticks (Borrelia hermsii)
Tick borne Relapsing Fever has the same pathogenesis as B. burgdorferi, except that they remain _____ instead of _____
Remains in bloodstream instead of disseminating to the organs
Evaluating blood smears patients with B. recurrentis after a febrile episode reveals _____
The appearance of a “thread” between erythrocytes
The most evident feature of B. recurrentis infection is _____
Cyclic fever and chills
T/F No Borrelia species have an animal reservoir
FALSE
The tick-borne form of Relapsing Fever (caused by B. hermsii) has a rodent reservoir.
The treatment of Borrelia is a low dose beta-lactam instead of a high dose. Why is this the case?
High doses kill all of the organism at once causing a massive release of cytokines due to the sudden exposure to many pro-inflammatory mediators.
This is known as the Jarisch-Herxheimer reaction
What organism causes Leptospirosis?
Leptospira interrogans
How is L. interrogans transmitted?
Contact with urine
Enters through mucous membranes or damaged skin
The acute stage of Leptospirosis (leptospiremia) is characterized by _____
Spiking fever due to the organism changing its antigens (about one week)
How does L. interrogans appear under a microscope?
Motile, Gram (-) spiral/question-mark shaped organism with hooked ends
Serology for _____ in CSF or blood is used for acute phase diagnosis of Leptospirosis.
IgM antibodies
The convalescent phase of Leptospirosis (Weil’s syndrome) occurs when the organism spreads to _____, causing what symptoms?
Organism spreads to liver and kidneys
Sx: Jaundice, renal failure, can cause myocarditis. Autoimmune uveitis and interstitial nephritis may result
How is Leptospirosis identified in the clinic?
Microscopic agglutination test or cultured in vitro
What are the three treatment options for Leptospirosis?
1) Doxycycline
2) Penicillin
3) Fluoroquinolone
What organism causes Rocky Mountain Spotted Fever?
Rickettsia rickettsi
What virulence factor of R. ricketsii is the immunodominant surface-exposed antigen responsible for adhesion?
rOmpA
What virulence factor of R. ricketsii mediates internalization of the organism?
Phospholipase
R. ricketsii is introduced into the host by _____
Saliva of Dermacentor tick
T/F R. ricketsii is a facultative intracellular pathogen
FALSE
R. ricketsii is an OBLIGATE intracellular pathogen
R. ricketsii, after entering the bloodstream, infects the _____ of lungs, spleen, brain, and skin.
Vascular endothelium
After infecting the vascular endothelium, R. ricketsii causes _____. Patients preset with a characteristic _____ on the extremities
R. ricketsii causes vasculitis
Patients often have a characteristic petechial rash on their extremities
What are the three treatment options for R. rickettsi infection/Rocky Mountain Spotted Fever?
1) Tetracycline
2) Chloramphenicol
3) Fluoroquinolones
What organism causes Epidemic Typhus?
Rickettsia prowazekii
Where are breakouts of Epidemic Typhus often concentrated
POW camps/Internment centers/Slums - Anywhere there’s a lot of people with poor sanitation crowded together and head lice
What is the vector for R. prowazekii?
Human head/body live (P. humanus capitis/corporis)
What is the animal reservoir for R. prowazekii?
Flying squirrels
T/F R. prowazekii is an obligate intracellular pathogen?
TRUE
Both Rickettsia species are obligate intracellular pathogens
How does R. prowazekii gain access to its human host?
Louse feeds and defecates (R. prowazekii is in the feces) simultaneously
Bite itches –> Host scratches bite –> Feces/bacteria rubbed into wound
T/F Epidemic Typhus caused by R. prowazekii has similar symptoms and mortality to Rocky Mountain Spotted Fever caused by R. ricketsii
FALSE
The symptoms ARE similar, but Epidemic Typhus caused by R. prowazekii has a higher mortality (40%) than RMSF (10%)
_____ is a reemergence of an old typhus infection after the R. prowazekii lies dormant in the lymph nodes for many years?
Brill-Zinsser
What is the treatment for Epidemic Typhus caused by R. prowazekii?
Tetracycline & Chloramphenicol for 3-4 days
What organism causes Q Fever?
Coxiella burnetti
The phase I antigens of C. burnetii block _____
Antibodies to bacterial surface proteins
The phase II antigens of C. burnetii are derived from phase I, when the organism undergoes a _____. After this mutation, surface proteins on the bacterial cell wall become _____.
Deletion mutation
After mutation, C. burnetii cell wall proteins become exposed
The antibody against C. burnetii phase I antigens are found in _____ patients. The antibody against C. burnetii phase II antigens are found in _____ patients?
Phase I antibodies: Chronically ill
Phase II antibodies: Acutely ill
Many mammals function as reservoirs of C. burnetii. Which ones are the most well known reservoirs?
Farm animals
How is C. burnetii transmitted?
Humans inhale dust that’s infected with C. burnetii “spores” (not true endospores)
Where does C. burnetii replicate in the human host?
Inside phagocytes
T/F C. burnetii is an obligate intracellular pathogen
TRUE
C. butnetii is an obligate intracellular organism, just like Rickettsia
Acute disease caused by C. burnetii presents as an _____. It may spread to the liver, causing _____
Acute C. burnetii disease presents as an ATYPICAL PNEUMONIA (non-productive cough, no consolidation in lower lobes of lung)
Spread to the liver can cause DIFFUSE GRANULOMAS
Chronic disease caused by C. burnetii causes _____
Chronic endocarditis (on artificial/previously damaged valves)
How is C. burnetii diagnosed in the lab?
PCR or serology (looking for phase antigens)
What are the treatment options for Q fever caused by C. burnetii?
Tetracycline / Tetracycline + rifampin / Tetracycline + trimethoprim-sulfa
