Micro- Anthrax and Smallpox Flashcards
What is a category A bioterror agent?
- high mortality rate
- easily transmissible person-to-person
- special public health actions are necessary
- causes social disruption
What is a category B bioterror agents?
- moderate rates of illness but low mortality
2. moderately easy to disseminate
What is a category C bioterror agent?
- emerging infectious agent
- possible to produce easily
- potential for high morbidity and mortality
What 3 bacteria are “category A” bioterror agents?
- anthrax [bacillus anthracis]
- plaque [yersinia pestis]
- tularemia [francisella tularensis]
What 2 viruses are category A bioterror agents?
- smallpox [variola major]
2. Lassa, Marburg, Ebola, Denque
What toxin is category A bioterror agent?
Botulism/botulinum toxin
What are the category B bioterror agents?
- Q fever [coxiella burnetti]
- Brucelliosis
- Glanders/Meliodosis- burkholderia
- Psittacosis- chlamydia psittaci
- typhus [rickettsia prowazekii]
- food and waterborne pathogens [shigella, salmonella, campy]
What are the category C bioterror agents?
- MDR and XDR TB
- Viruses
- nipah
- hanta
- yellow fever
What are the advantages of biologics as weapons?
- easy to obtain
- inexpensive
- can be disseminated over large geographic areas
- perpetrator escapes easily
What is the “ideal microbe” for bioterror?
- infectious as aerosol
- stable in the environment
- susceptible population
- spread person-to-person
- high morbidity and mortality
- difficult to diagnose or treat
What are the 2 aerobic gram positive rods?
- bacillus
2. cornybacterium
What are the three inoculation sites for anthrax?
- inhalation
- cutaneous
- gastrointestinal
How do you acquire cutaneous anthrax?
What happens following inoculation?
It is acquired by contact with material contaminated with SPORES [textile from animal skin or hair, raw hides, wool]
After inoculation:
- development of papular lesion
- become vesicular with surrounding edema
- form a black eschar
It is painless
How do you acquire GI anthrax?
What is incubation period?
What is the presentation of disease?
What is the fatality rate?
Eating contaminated meat that is undercooked.
Incubation is hours to 7 days while spores germinate in your intestines.
Presents with:
- bloody diarrhea
- fever, vomiting
Case fatality is 25-75%
Describe inhalation anthrax. How is it acquired? How long is incubation? What are the initial symptoms? What are the later symptoms?
Inhalation of spores
Incubation 3 to greater than 40 days
Begins with non-specific flu-like illness
-fever, myalgia, headache, chest discomfort
*May have a period of transient improvement [RED]
Rapid deterioration to high fever, dyspnea, shock
What is the pathogenesis of inhalation anthrax?
- inhale 2micron particles
- ingested by alveolar macrophages which move to hilar lymph nodes
- germination, production of anthrax toxin in the lymph nodes
- Hemorrhagic necrosis of nodes and mediastinum
- Gelatinous pleural effusion with atelectasis
- seeding of other organs
- hemorrhagic meningitis
What are the 2 main virulence factors of B. anthracis?
- capsule
2. anthrax toxin
What are the inhalation anthrax major signs?
- fever, tachycardia, tachypnea
- toxic appearance
- signs of pulmonary consolidation or pleural effusion
- may NOT have pulmonary infiltrates since germination of spores is in the nodes in the mediastinum and NOT the lungs
Why may there not be pulmonary infiltrates in inhalational anthrax?
Because germination of the spores takes place in the nodes of the mediastinum and not in the lungs [RED]
How is the diagnosis of inhalational anthrax made based on :
- suspicion [RED]
- proof [RED]
Suspicion:
- widened mediastinum on CXR [RED]
- hemorrhagic mediastinal nodes on CT
- no rhinorrhea or conjunctivitis; pharyngitis unusual
Proof [RED]
- 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 treatment for inhalation anthrax [x60days]?
ciprofloxacin OR doxy [not effective against meningitis]
PLUS
1 or 2 additional antimicrobials [ vanc, penG, others]
What is the treatment for cutaneous anthrax [x7-10 days, unless aerosol exposure]
oral Cipro or Doxy
What is anthrax chemoprophylaxis?
How long is it given
Disease doesn’t begin until spores germinate [maybe weeks later]
If the person may have been exposed, treat them for a long time [over 60 days] with cipro or doxy p.o.
Who receives the anthrax vaccine?
How is it delivered?
Vaccine is given to military personnel and occupational exposures.
It has protective antigen and requires multiple injections over a period of weeks.
Is isolation of patients with Anthrax exposure required?
No because it is not transmitted person-to-person.
It is inhalation of spores that causes illness.
Anthrax spores remain viable for decades. What 2 professions are at highest risk for inhalation?
- animal husbandry
2. veterinary medicine
What virus family does smallpox belong to?
Orthopox virus family
[other pox viruses = cowpox, monkeypox, molluscum cantagiosum, vaccinia]
What is the genome of smallpox virus?
Describe the structure of the virus from in to out.
Genome: dsDNA
Structure:
- nucleosome surrounded by core membrane
- Lateral body
- outer membrane
- envelope
- surface tubule
What is the other name for smallpox?
When was it eradicated?
Why is this still an issue?
Variola major
It was eradicated in 1977 but it is still an issue because Russia and the US each have a vial.
It is a potential bioterror agent that would have huge morbidity, mortality, and social disruption [category A]
How is smallpox spread?
What is the usual scenario?
It is spread person-to-person via aerosol or droplet nuclei
Usual scenario: secondary infection of household members, then of hospital personnel [school outbreak is unusual]
What is “multiplication factor” for smallpox?
2-10 new cases per case of smallpox
What is the most helpful feature of preventing transmission of smallpox [RED]?
fever precedes the rash, infectivity accompanies rash
How long can smallpox virus survive in the environment?
2 days
Describe the progression of disease for smallpox.
What is the incubation period?
What is the first sign of illness?
When do they become infectious?
- infection
- 7-17 day incubation period
- Fever 2-3 days prior to rash
- rash first appears on oral mucousa, face and forearms then spreads to trunk and legs [this is the infectious stage]
The rash lasts 1-2 weeks
Smallpox progresses from macule/papules to vesicles to pustules to scabs.
Describe the vesicles.
deeply embedded in the dermis and feel like firm round objects implanted in the skin
When are patients most infectious with smallpox?
When do they cease to be infectious?
In the first week of the rash when oral lesions ulcerate and release virus into the saliva.
They are no longer infectious when the scabs have separated [3-4 weeks after onset of rash]
What organs does smallpox viremia disseminate to?
What is the case fatality ratio?
- Lungs
- Liver
- GI tract
Case fatality ratio = 30%
According to the CDC, what are the 3 MAJOR deteminants of smallpox? [RED]
What are the 4 minor?
MAJOR:
- febrile prodrome [>101 F] 1 to 4 days before rash onset
- rash lesions are firm deep or hard
- Lesions are the same stage of development on any part of the body [RED]
MINOR:
- centrifugal distribution
- first appearance on oral mucousa or face
- toxic appearance
- slow evolution of lesions over days
Do patients with smallpox require isolation?
They do not need to be isolated until they develop a fever. Check temp once a day and isolate in their home if they are above 101.
How does incubation period compare for chickenpox and smallpox?
Chickenpox = 12-21 days Smallpox = 12-14 dats to fever, 2-3 more for rash
How does the location of the rash differ from chicken pox and smallpox?
Chicken pox= most prominent on the trunk and does not involve palms or soles.
Smallpox = most prominent on face and extremities. INVOLVES PALMS AND SOLES
How does the appearance of the rash differ for chicken pox and smallpox?
Chickenpox = lesions at different stages of development
Smallpox= all lesions at the same stage of development
How do diagnostic tests differ for chickenpox and smallpox?
Chickenpox:
- serum IgM
- Tzanck prep
- culture or PCR of vesicle fluid
Smallpox
- culture, PCR, electron microscopy of vesicular fluid
* must be done at CDC
What evidence must there be for the smallpox vaccine to be considered successful?
There must be evidence that the vaccinia virus has replicated in the host as evidenced by the formation of the “Jennerian vesicle” which is maximal at 7 days post vaccination. It will scab, fall off and be a scar by day 21
What are the common side effects of smallpox vaccination?
What occur in under 500 cases per million?
- fever, chills, swelling and tenderness of regional lymph nodes
Rare:
- autoinoculation of eyes, face, nose, mouth
- generalized vaccinia
- eczema
- progressive vaccinia
- postvaccine encephalitis
- myocarditis
What are the 5 contraindications for smallpox vaccine?
- eczema
- immunosuppression
- household contact of eczema or immunocompromised
- pregnant
- allergic to vaccine components
What are the steps you do if you suspect someone has smallpox?
- isolate suspect and do NOT let them go to the hospital
- notify health department
- incubation is at least 7 days so during this interval contacts do not need to be isolated.
* vaccine given during the first few days may be protective - isolate when the fever comes
