Bioterrorism Flashcards
What are the three groups biologic agents are divided into?
Bacteria
Viruses
Toxins
What are the biologic agents that are considered to have the most severe potential?
Bacillis anthracis (anthrax) Yersinia pestis (plague) Variola major (smallpox) Francisella tularensis (tularemia) Clostridium botulinum (botulism) Filoviruses and arenaviruses (viral hemorrhagic fevers)
Organism for anthrax
B. anthracis
Gram-positive spore-forming bacterium
Appears as long chains, resembling bamboo or boxcars
Where is anthrax found?
In grass-eating mammals that ingest or inhale the spores while feeding
Humans become infected by eating infected animals or through contact (skin or inhalation) with spores on the fur or hide of animals
What are the three forms of anthrax?
Cutaneous -Most common Pharyngeal or gastrointestinal Inhaled -Most deadly
Pathophysiology of anthrax
Exposure to spore via skin (or worse) inhalation Spores germinate into bacilli Transported to regional lymph nodes Release toxins Sx
Prevention of anthrax
Vaccine available to military at risk only
Cipro or doxy prophylaxis for 30 days (with vaccination) or 60 days (no vaccination)
Sx/exam of anthrax
Painless papules that become vesicular with significant edema Progress to ulcerated black eschar in 1 wk Constitutional sx (fevers, chills, myalgias) and lymphadenopathy
Pharyngeal or GI anthrax
Ulcers and edema of pharynx followed in 5 days by abdominal pain, upper and lower GI bleeding
Inhaled anthrax
Mild flu-like sx that rapidly progress to respiratory distress and septic shock
Diagnosis of anthrax
Primarily a clinical dx CXR Mediastinal lymphadenopathy (CT is more sensitive than CXR) Possible pleural effusions May be clear of infiltrates Gram stain and culture of skin lesions Tissue or pleural fluid evaluation
Tx of anthrax
Supportive and symptomatic care
Simple cutaneous anthrax (nontoxic): Cipro, doxy, or amoxicillin
Toxic pts or inhalational dz; require triple antibiotic therapy
-Cipro or doxy plus two other abx (e.g., rifampin, clinda)
Antibiotic therapy must continue for 60 days
Plague organism and how it’s transmitted
Y. pestis, a Gram-neg bacillus
Normally a dz of rodents transmitted to humans by inhalation of flea feces or bite of infected flea
Forms of dz- plague
Bubonic (skin)
-Bacilli migrate to regional lymph nodes- bubo
Pneumonic (inhalational)
-MC: may be transmitted person to person
Septicemia (from secondary dissemination)
Bubonic plague
Two to three days incubation followed by:
- Regional painful lymph node inflammation and necrosis (bubo)
- Fevers, chills, malaise
- Will disseminate over next week in 50% (if untreated)
- Leads to septicemia
Pneumonic plague
Two to three days incubation followed by:
- Abrupt onset of fevers, chills, and flulike illness
- Severe pneumonia in 24 hrs
- Pts may develop meningitis, liver injury, coagulation disturbances, and gangrene in extremities (black death)
Septicemic plague
Characterized by endotoxemia, shock, DIC, and coma
Dx of plague
Suspect in any healthy individual who develops overwhelming Gram-negative sepsis
Gram stain and culture all body fluids
Tx of plague
Isolate pts Do not incise and drain fluctuant lymph nodes (aspiration ok) Abx: Multiple choices available Mild bubonic may be treated at home Prophylaxis: Same drugs for 7-day course
Smallpox
Organism: V. major, a large DNA virus
Was successfully eradicated in 1980 with small pox vaccine, but US and Russia have viral repositories for research purposes
Threat to resurface d/t lack of vaccination
Clinical forms of smallpox
Variola major and minor- 90% of cases
-The classic form of dz
Hemorrhagic
Malignant
Sx/exam of smallpox- variola major and minor
Incubation period of 2 wks followed by:
- Constitutional sx
- Maculopapular rash
- Begins in mouth
- Predilection for face, then spreads distally involves palms and soles
- Changes from vesicular to pustular with all lesions in same stage
Sx/exam of smallpox- hemorrhagic
Quicker and more toxic course
Petechiae and hemorrhage
Ninety percent mortality rate
Sx/exam of smallpox-malignant
Also quicker and more toxic course
Lesions are flatter and never progress to pustules
Major criteria for smallpox
Febrile prodrome
Classic smallpox lesions
Lesions in some stage of development
Minor criteria for smallpox
Centrifugal distribution of pustules Toxic appearance First lesions in mouth, face or forearms -Slow evolution of lesions Pustules on the palms and soles
Major and minor criteria- how they come into play for smallpox
Three major- presumed dz
Two major or one major and four minor- probable disease
Fever than four minor- dz not likely
Lab PCR identification of variola DNA in a clinical specimen
Tx of smallpox
Isolate pt
Very contagious until all scabs fall off
Exposed persons- vaccinate within 3 days to prevent or attenuate dz. Vaccinia immunoglobulin is given simultaneously with vaccine and redosed as needed to limit complications of vaccination
Antivirals are being investigated as tx
Tularemia
Organism: Francisella tularensis, a Gram-neg intracellular bacterium
Tularemia is transmitted primarily from ticks, lagomorphs, and rodents via direct contact or ingestion of infection water, soil, or fomites
Several forms exist depending on route of contact
Localized dz with regional lymph node involvement- tularemia
Ulceroglandular: MC- ulcers with LAD
Glandular: 2nd MC LAD without skin lesions
Oculoglandular: Conjunctivitis with preauricular LAD
Oropharyngeal: Severe pharyngitis with cervical lymphadenitis
Invasive and generalized dz- tularemia
Typhoidal
-Fevers, chills, GI sx, NO skin lesions
Pulmonary
-Fevers, chills, SOB, nonproductive cough
Dx of tularemia
Based on clinical findings
Antibody titers, rapid PCR
Tx of tularemia
Isolation is not required
Antibiotic: Streptomycin is drug of choice
Prophylaxis= doxycycline
Organisms in viral hemorrhagic fevers
Filoviruses and grenaviruses
Normally transmitted via mosquitoes, rodents, or their parasites
Sx/exam of viral hemorrhagic fevers
Incubation period from 4-21 days, followed by:
- Fevers, myalgias, prostration
- Petechial hemorrhage, DIC
- Multisystem organ dysfunction, cardiovascular collapse
Dx of viral hemorrhagic fevers
ELISA
PCR
Tx of viral hemorrhagic fevers
Supportive care
Antiviral: Ribavirin
Prophylaxis: Ribavirin
Nerve agents
Organophosphates
Include sarin, soman, VX (vesicant?)
Vesicants
Agents that induce blistering via cellular damage, including mustard
Pathophysiology of nerve agents
Inhibit acetylcholinesterase
Leads to accumulation of acetylcholine at muscarinic and nicotinic receptors
Leads to cholinergic toxidrome
Sx/exam of nerve agents
Cholinergic toxidrome Salivation/sweating Lacrimation Urination Defecation Excretion? GI distress Emesis Miotic pupils Fasciculations Muscle weakness Apnea AMS Seizures
Dx of nerve agents
Based on hx exposure and clinical presentation
Tx of nerve agents
Supportive care
Atropine dosed to secretion control (may require 2-4 mg at frequent intervals)
Pralidoxime chloride (2-PAM) to reverse paralysis
Benzodiazepines for seizures
Sx/exam of vesicants
Local skin effects: Severe pain, vesicle formation, and inflammation to site of contact
Skin injury resembles second-degree burn
Inhalation effects: Pharyngeal edema and pulmonary necrosis- varying degrees of respiratory distress
Systemic effects: Bone marrow suppression
Tx for vesicants
Skin and mucus membrane decontamination with irrigation
Supportive care
