Micro: Anthrax and Smallpox

Question 1

What is the general classification of bioterrorism agents?

Answer 1

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

Question 2

What are the basic features of bacillus anthracis?

Answer 2

large, spore forming gram+ rod

cutaneous, GI, or inhalational inoculation

Question 3

What are the features of cutaneous anthrax?

Answer 3

contact w materials contaminated by spores

form painless black eschars

Question 4

What are the features of GI anthrax?

Answer 4

ingestion of uncooked contaminated meat
germination of spores in intestines
fever, vomiting, diarrhea, high fatality even w treatment

Question 5

What are the features of inhalational anthrax?

Answer 5

inhale spores, begins w nonspecific flu-like illness
*may have period of transient improvement
rapid deterioration follows: shock, dyspnea, high fever
death if untreated

Question 6

What is the pathogenesis of inhalational anthrax?

Answer 6

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

Question 7

What are the virulence factors of b. anthracis?

Answer 7

capsule and toxins

Question 8

What are signs that can suggest inhalational anthrax?

Answer 8

fever, tachy, tachypnea, toxic appearing, effusions

*may not be pulmonary infiltrates since germination of spores typically occurs in lymph nodes of mediastinum

Question 9

How is inhalational anthrax diagnosed?

Answer 9

*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

Question 10

What is the treatment for anthrax?

Answer 10

cipro or doxy
longer for inhalational + 1 or 2 additional antimicrobials
vaccine reserved for military personnel and occupational exposure

Question 11

What are important public health features of anthrax?

Answer 11

not transmissible person to person - no isolation needed

spores remain viable for decades

Question 12

What is the microbiology of smallpox?

Answer 12

orthopox family, dsDNA, enveloped

variola major and variola minor (smaller, less lethal)

Question 13

What is the epidemiology of smallpox?

Answer 13

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

Question 14

What are the features of the smallpox rash?

Answer 14

begins in mouth, then face and forearms, then trunk and legs

vesicles embedded in dermis - feel like firm round objects implanted in skin

Question 15

What happens w smallpox viremia?

Answer 15

disseminates to multiple organs - lung, liver, GI

no proven effective chemotherapy, fatality 30%

Question 16

What are the CDC definitions of smallpox?

Answer 16

• 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

Question 17

What are some important differences between chickenpox vs. smallpox?

Answer 17

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

Question 18

*What must happen for the smallpox vaccine to be considered successful?

Answer 18

*evidence that virus has replicated in patient = formation of Jennerian vesicle (maximal at day 7, scabs by 21, falls off and leaves scar)

Question 19

What are the possible side effects of smallpox vaccination?

Answer 19

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

Question 20

What are contraindications for the smallpox vaccine?

Answer 20

eczema, immunosuppresion, household contact of someone w these two
pregnancy
allergy to vaccine components

Question 21

What are important public health points regarding smallpox?

Answer 21

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