Ch2: Skin, Musculoskeletal, Blood and Lymph Part I Flashcards
What is Borrelia?
Extracellular, irregularly, loosely coiled spirochete
What are the 3 infections caused by Borrelia?
Reservoir for each?
Vector for each?
Relapsing Fever Epidemic: Humans (Body Louse)
Relapsing fever endemic: Rodents, soft ticks (Soft ticks)
Lyme disease: Rodents, deer, pets, hard ticks (Hard ticks)
Why does borrelia show up in waves in blood smears over time?
Clinically how do this present?
Antigenic variation
Relapsing fever
Both types of relapsing fever have what symptoms? (5)
- Acute onset of high fever with rigors
- Severe headache
- Myalgias
- Arthralgias
- Lethargy
Diagnosis of borrelia hermsii is done how?
Specifically how? 2
Identification of spirochetes in blood smears
- Look for outer membrane with flagella in periplasmic space
- Corkscrew motion of flagella
If Borrelia hermsii stains at all in gram stain, how will it stain?
Positive
Control for borrelia?
Avoid habitat of the vectors
treatment of borrelia hermsii? (4)
- Tetracycline (#1)
- Chloramphenicol
- Doxycycline
- Erythromycin
Borrelia burgdorferi (Lyme disease) is different from B. hermsii how?
Smaller
Reservoirs for B. burgdorferi? (3)
Deers
Deer mice
Birds
Vector for B. burgdorferi?
Deer tick/Hard tick
What form of ticks is small, overloked and feeds on many types of animals?
Nymphs
The longer the tick is attached, the better what is?
Chance of transmission
Who engorge faster, nymphs or adults?
Nymphs
Who has a painless bite, adults or nymphs?
Nymphs
Nymphs are prevalent during what months?
Spring and summer
What are the steps for tick transmission?
- Engorge slowly
2. Transmit afterawhile
What are the 3 stages of b. burgdorferi disease/lyme disease?
Stage 1: Acute lyme disease
Stage 2: Chronic lyme disease
Stage 3: Chronic monoarthritis and migratory polyarthitis
Acute lyme disease/stage1 has what two components? 2
- Target shaped rash: Erythema migrans
2. Flu-like symptoms
How long does erythema migrans last?
A week
Chronic lyme disease has what manifestations? 3
- Cardiac
- Neurologic
- Skin
The stage 3 arthritis is due to what?
Immune complex mediated Hypersensitivity Type III
Laboratory diagnosis has what 3 parts?
- Characteristic symptoms
- Exposure in endemic area
- Positive Ab response to B. burgdorferi OR Erythema migrans
What do you culture B. burgdorferi in to determine diagnosis?
Barbour-Stoenner-Kelly (BSK) medium
How is PCR used in diagnosing B. burgdorferi?
Detect in joint fluid
What is most important feature in diagnosig b. burgdorferi?
Antibody positive test
Control and treatment for borrelia burgdorferi? (4)
Most important?
- Doxycycline: Most important
- Amoxicillin
- Erythromycin
- Ceftriaxone: later manifestations
Rickettsia species is what size?
Gram stain result?
Shape?
Small
Gram negative
Coccobacilli
What metabolic feature is unique to Rickettsia?
Unique transport systems for NAD and ATP
What can some species of Rickettsia polymerize?
Actin
Are all Rickettsia zoonoses?
Exception?
Yes
Rickettsia prowazekii
Are all Rickettsia vector borne?
Yes: Lice, ticks, fleas, mites
Rocky mountain spotted fever is caused by what?
Vector?
Reservoir?
R. rickettsii
Tick
Tick and wild rodents
Rickettsialpox is caused by what?
Vector?
Reservoir?
R. akari
Mites
Mites and wild rodents
Scrub typhus is caused by what?
Vector?
Reservoir?
O. tsutsugamushi
Mite
Mites and wild rodents
Epidemic typhus is caused by what?
Vector?
Reservoir?
R. prowazekii
Louse
Humans, squirrel fleas, flying squirrels
Murine endemic typhus is caused by what?
Vector?
Reservoir?
R. typhi
Fleas
Wild rodents
All Rickettsia preferentially infect and replicate within what?
How does this show up?
Endothelial cells lining small blood vessels
Vascular leakage and red dots
Clinical manifestations of Rickettsia result from what?
Infection of endothelial cells –> Vasculitis (Primary reason for signs)
What determines symptoms of Rickettsia?
What is prominent in all? 2
Organs involved
Skin rashes
Pneumonia is common
When does Rickettsia typically turn deadly?
After getting pneumonia
Laboratory diagnosis of Rickettsia? 5
Which is most common?
- Culture embryonated eggs or tissue culture
- Immuno staining of tissue samples for Rickettsia antigens
- Serology: Most common
- PCR
- Stain with Giemsa or Gimenez stain
Control of Rickettsia?
Limiting exposure (avoid the vector habitat)
Treatment of Rickettsia?
Tetracyclines
What are the four members of the spotted fever group of Rickettsia?
Species with each?
Rocky mountain spotted fever: R. rickettsii
Mediterranean spotted fever: Rickettsia conorii
Rickettsialpox: Rickettsia akari
Others: R. sibirica, australis, japnoica
What symptom dominates in spotted fever group?
Rash
The members of the typhus group of Rickettsia? 2
Species for each
Epidemic typhus: R. prowazekii
Endemic murine typhus: Rickettsia typhi
What symptom dominates typhus group?
Fever
R. Rickettsii can polymerize what?
Allows it to do what?
Actin
Move intracellularly from cell to cell
Reservoirs of r. Rickettsia?
Vectors?
Wild rodents
Ticks (Dermacentor species) Wood ticks, dog ticks
Rocky mountain spotted fever is seen most where? (2)
- Eastern seaboard
2. SE USA
Describe the rash in R. Rickettsia?
Hemorrhagic rash starting with palms and soles and spreads centripetally (From extremities to torso)
What respiratory manifestation is seen commonly in R.Rickettsia causing death?
Pneumonia
In Classic RMSF, death occurs when?
7 to 15 untreated days after onset of symptoms
In fulminant (fast) RMSF, death occurs when?
First 5 days
What is the reservoir for rickettsia akari?
What is the vector?
House mouse
Mite ectoparasite
Human disease caused by rickettsia akari?
Similar to what?
Is it fatal?
What is the triad of symptoms in r. akari?
Rickettsial pox
Chicken pox
Not fatal
Fever, Rash, Eschar
Diagnosis and treatment for r. akari?
Same as other rickettsia (Tetracycline)
Ricketssia prowazekii has what reservoir? 2
Vector for humans? (2)
Humans and Flying squirrels
Human head and body louse
How does ricketssia prowazekii get into blood stream?
Louse gets on human skin –> Rickettsiae shed in louse feces –> Human scratches
Human disease from rickettsia prowazekii?
Epidemic typhus
Two main symptoms of epidemic typhus?
- Skin rash of macules that disappear on pressure and maculopapules with petechiae that do NOT involve face, palms, or soles and spreads centrifugally (Torso –> Outward)
- Pneumonia: Fatal
What is the recurrent form of epidemic typhus called?
Brill-Zinsser disease
Laboratory diagnosis for epidemic typhus is what?
And when is this detected?
Detection of a 4X rise in Ab titer in convalescence
Second week of illness
Rickettsia typhi
Reservoir?
Vector?
Human disease name?
Rats
Rat fleas
Endemic murine typhus
How does r. typhi caused endemic typhus compare to epidemic typhus?
Similar but not as severe
Diagnosis and treatment for R. typhi?
Same as R. prowazekii
What causes scrub typhus?
Orientia tsutsugamushi
Orientia tsutsugamushi
Size and shape?
Gram stain?
Type of metabolism?
Small coccobacillus
Gram negative
Orientia tsutsugamushi
Reservoir?
Vector?
Habitat of vector
Rodents
Chiggers
Scrub