• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/19

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

19 Cards in this Set

  • Front
  • Back
Anthrax
• Caused by Bacillus anthracis, a non-motile Gram-positive rod
• Natural disease of herbivores
• Produces three exotoxins:
– Edema factor
– Lethal factor
– Protective antigen
• Not contagious
Cutaneous Anthrax
• Route of infection: Direct inoculation of spores
• Incubation period: 1-7 days (may be up to 14 d)
• Clinical findings
– Pruritic macule -> vesicle ->round ulcer -> black eschar over 1-2 weeks
– Surrounding edema/erythema but painless
– +/- painful regional lymphadenopathy
• Untreated, ~ 5%-20% fatality rate
Cutaneous Anthrax: Diagnosis
• Vesicular fluid or border of skin lesion:
– Gram stain, culture and sensitivity
– PCR
• Skin biopsy
– Culture and PCR (fresh frozen)
– Immunohistochemistry (formalin-fixed)
• Serology:
– Acute- and convalescent-phase serum IgG (ELISA IgG antibody against protective antigen)
Inhalational Anthrax
• Route of infection: Inhalation of spores (1-5 microns in size) into terminal bronchioles and alveoli
• Incubation period ~ 1-6 d (range 1- ?100 d)
Inhalational Anthrax

Pathogenesis
• Once deposited, inert spores reside within alveoli (days – weeks)
• Spores taken up by alveolar macrophages -> regional lymph nodes
• Spores germinate, producing vegetative cells that proliferate within macrophages, produce toxins and enter the bloodstream
Inhalational Anthrax

Clinical manifestations
• Initial symptoms resemble “flu”
• Late symptoms include high fevers, vomiting, respiratory distress, and necrotizing hemorrhagic mediastinitis
• Fatal within 24-36 hours if treatment delayed
Inhalational Anthrax

Diagnosis
• Non-specific physical findings
• CXR: mediastinal adenopathy, pleural effusions
• Gm stain/culture (or PCR) of blood, pleural fluid, and CSF
– Large Gm (+) rods
– Rough, grayish colonies - non-hemolytic, non-motile
• Suspect cultures should be sent to NYCDOH/CDC
Inhalational Anthrax

Treatment
• Antibiotics are effective against vegetative B. anthracis but not against the spore form
• Mortality rate 100% despite aggressive Rx in “advanced disease” but is lower with early treatment
Anthrax Vaccine
• Culture supernatant (protective antigen) of attenuated, non-encapsulated strain
• Protective against cutaneous (human data) and possibly inhalational anthrax (animal data)
• Injections at 0, 2, 4 wks & 6, 12, 18 mos; followed by yearly boosters
• 83% serologic response after 3 doses, 100% after 5
• Current vaccine supplies are limited
Inhalational Anthrax

Prevention
• Primary prevention
Vaccination of persons most at risk for exposure to anthrax spores
• Post exposure prophylaxis
Vaccination of persons who have been exposed to aerosolized anthrax spores to prevent delayed spore germination and inhalational disease
Anthrax

Post-Exposure Prophylaxis
• Disease can be prevented as long as therapeutic antibiotic levels maintained until all spores cleared or controlled by immune defenses
• Viable spores demonstrated in mediastinal lymph nodes of monkeys 100d post-exposure
• Start oral antibiotics ASAP after exposure
– Antibiotics for 100 days without vaccine
– Antibiotics for 30 days with 3 doses of vaccine (0, 2 and 4 weeks)
Smallpox as a Bioterrorist Weapon
• Infectious via aerosol
• Rapid person-to-person transmission
• Worldwide immunity has waned
• Severe morbidity and mortality
• Clinical inexperience
• Potential to overwhelm medical care and public health systems (large-scale vaccine campaigns)
Smallpox
• Incubation period 12-14 d (range 7-17 d)
• Vaccination of contacts within 4 days of exposure is effective in preventing illness
• Contagiousness begins with onset of rash
• Isolation measures effective in controlling outbreaks even with limited vaccine use
Smallpox

Pathogenesis
• Implantation on oral or respiratory mucosa
• Migration to regional lymph nodes
• Initial asymptomatic viremia – day 3 or 4
• Multiplication in reticuloendothelial tissues
• Secondary symptomatic viremia – ~ day 8
Smallpox

Clinical Features
• Incubation period is 12-14 days (7-17d)
• Abrupt onset of high fever, malaise, rigors, vomiting, backache, and headache
• Followed in 2-3 d by maculopapular rash
• Generally not infective until rash appears
Smallpox

Exanthem
• Maculopapular rash
• Starts on face (including oral mucosa), forearms, or pharynx (centrifugal distribution)
• Spreads to trunk and legs
• Lesions on palms and soles common
• Macules/papules -> vesicles -> pustules
• Synchronous development
• Deeply embedded in dermis
Smallpox

Diagnosis
• Requires astute diagnostician to distinguish from varicella or erythema multiforme
• Swab of vesicular/pustular fluid or removal of scab for culture, EM, variola-specific PCR assay at CDC BSL4 laboratory
Smallpox v Chickenpox
Small pox
• Incubation 7-17 days
• Prodrome 2-4 days
• Distribution Centrifugal
• Evolution Synch
• Depth of lesion Dermal

Chicken pox
• Incubation 14-21 days
• Prodrome Minimal
• Distribution Centripetal
• Evolution Asynch
• Depth of lesion SubQ
Smallpox

Medical Management
• Even one suspect case is an international emergency requiring immediate reporting to public health authorities
• Strict quarantine with both respiratory and wound isolation (negative airflow pressure and HEPA filtration)
• No proven Rx (cidofovir effective in vitro)