Micro: Anthrax and Smallpox Flashcards
What is the general classification of bioterrorism agents?
category A: high mortality, easy transmission, need special public health actions
category B: moderate rates of illness but low mortality, moderately easy to disseminate
category C: emerging agents, possible to produce easily, potentially high rates of morbidity/mortality
What are the basic features of bacillus anthracis?
large, spore forming gram+ rod
cutaneous, GI, or inhalational inoculation
What are the features of cutaneous anthrax?
contact w materials contaminated by spores
form painless black eschars
What are the features of GI anthrax?
ingestion of uncooked contaminated meat
germination of spores in intestines
fever, vomiting, diarrhea, high fatality even w treatment
What are the features of inhalational anthrax?
inhale spores, begins w nonspecific flu-like illness
*may have period of transient improvement
rapid deterioration follows: shock, dyspnea, high fever
death if untreated
What is the pathogenesis of inhalational anthrax?
ingestion by alveolar macrophages - move to hilar lymph nodes - germination and production of anthrax toxin
hemorrhagic necrosis of nodes, mediastinum
gelatinous pleural effusion –> atelectasis
bacteremic seeding of other organs –> meningitis
What are the virulence factors of b. anthracis?
capsule and toxins
What are signs that can suggest inhalational anthrax?
fever, tachy, tachypnea, toxic appearing, effusions
*may not be pulmonary infiltrates since germination of spores typically occurs in lymph nodes of mediastinum
How is inhalational anthrax diagnosed?
*widened mediastinum (CXR)
hemorrhagic mediastinal nodes (CT)
*proof: culture, PCR, or immunohistochemistry of nasopharyngeal swab, sputum, pleural fluid
blood culture, gram stain and culture of CSF, serology - IgG to protective antigen
What is the treatment for anthrax?
cipro or doxy
longer for inhalational + 1 or 2 additional antimicrobials
vaccine reserved for military personnel and occupational exposure
What are important public health features of anthrax?
not transmissible person to person - no isolation needed
spores remain viable for decades
What is the microbiology of smallpox?
orthopox family, dsDNA, enveloped
variola major and variola minor (smaller, less lethal)
What is the epidemiology of smallpox?
person to person via aerosol or droplet nuclei
usually infect other household members, then hospital personnel
*helpful feature for preventing transmission: fever precedes rash, while infectivity accompanies rash (isolate when fever hits)
virus dies in 2 days in environment
What are the features of the smallpox rash?
begins in mouth, then face and forearms, then trunk and legs
vesicles embedded in dermis - feel like firm round objects implanted in skin
What happens w smallpox viremia?
disseminates to multiple organs - lung, liver, GI
no proven effective chemotherapy, fatality 30%
What are the CDC definitions of smallpox?
- major and minor
major: febrile prodrome, rash lesions, *lesions in same stage of development on any part of body
minor: first appearance of lesions on face and arms, toxic appearance, slow evolution of lesions over several days
What are some important differences between chickenpox vs. smallpox?
no palms and soles vs. palms and soles
more prominent on trunk vs. face and extremities
lesions at different stages of dev vs. all at same stage
*What must happen for the smallpox vaccine to be considered successful?
*evidence that virus has replicated in patient = formation of Jennerian vesicle (maximal at day 7, scabs by 21, falls off and leaves scar)
What are the possible side effects of smallpox vaccination?
fever, chills, myalgias, tender regional lymph nodes, etc
autoinoculation of eyes, face, nose, mouth, genitals, rectum
generalized vaccinia, eczema vaccinatum, progressive vaccinia, postvaccinal encephalitis, myocarditis
What are contraindications for the smallpox vaccine?
eczema, immunosuppresion, household contact of someone w these two
pregnancy
allergy to vaccine components
What are important public health points regarding smallpox?
isolate suspected cases immediately when fever occurs
vaccine w/i 7 day incubation may be protective
initial rash = enanthem on oral mucosa, pox rash appears 1-3 days later, enanthem still infectious
