BIOTERRORISM
HISTORY
• Microbial pathogens were used as potential
weapons of war or terrorism from ancient times:
– the poisoning of water supplies in the sixth century
B.C. with the fungus Calviceps purpurea (rye ergot)
by the Assyrians
– the hurling of the dead bodies of plague victims over
the walls of the city of Kaffa by the Tartar army in
1346
– the spreading of smallpox via contaminated blankets
by the British to the native American population loyal
to the French in 1767.
Key Features of Biologic Agents
Used as Bioweapons
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High morbidity and mortality
Potential for person-to-person spread
Low infective dose and highly infectious by aerosol
Lack of rapid diagnostic capability
Lack of universally available effective vaccine
Potential to cause anxiety
Availability of pathogen and feasibility of production
Environmental stability
Database of prior research and development
Potential to be “weaponized”
CLASSIFICATION
• Centers for Disease Control and Prevention (CDC) classifies potential
biologic threats into three categories: A, B, and C
• Category A agents are the highest-priority pathogens:
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can be easily disseminated or transmitted from person to person
result in high mortality rates
have the potential for major public health impact
might cause public panic and social disruption
require special action for public health preparedness.
• Category B agents include those that are moderately easy to
disseminate, result in moderate morbidity rates and low mortality rates,
and require specifically enhanced diagnostic capacity.
• Category C agents include emerging pathogens
– the general population lacks immunity
– could be engineered for mass dissemination in the future because of
availability, ease of production, ease of dissemination
– The recent emergence of novel viruses leading to outbreaks of severe
acute respiratory syndrome (SARS), Nipah, hantavirus are examples
Category A agents
• Anthrax (Bacillus anthracis)
• Botulism (Clostridium botulinum toxin)
• Plague (Yersinia pestis)
• Smallpox (Variola major)
• Tularemia (Francisella tularensis)
Viral hemorrhagic fevers:
• Arenaviruses: Lassa, New World (Machupo, Junin,
Guanarito, and Sabia)
• Bunyaviridae: Crimean Congo, Rift Valley
• Filoviridae: Ebola, Marburg
• Flaviviridae: Yellow fever; Omsk fever; Kyasanur Forest
Category B agents
• Brucellosis (Brucella spp.)
• Epsilon toxin of Clostridium perfringens
• Food safety threats:
– Salmonella sp.
– Escherichia coli 0157:H7
– Shigella sp.
• Water safety threats
– Vibrio cholerae
– Cryptosporidium parvum)
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Glanders (Burkholderia mallei)
Melioidosis (B. pseudomallei)
Psittacosis (Chlamydia psittaci)
Q fever (Coxiella burnetii)
Ricin toxin from Ricinus communis (castor beans)
Staphylococcal enterotoxin B
Typhus fever (Rickettsia prowazekii)
Viral encephalitis
– alphaviruses (e.g., Venezuelan, eastern, and western equine
encephalitis)
Anthrax as a Bioweapon
• Anthrax may be the prototypic disease of bioterrorism
although rarely spread from person to person
• U.S. and British government scientists studied anthrax
as a biologic weapon beginning approximately at the
time of World War II (WWII).
• Soviet Union in the late 1980s stored hundreds of tons of
anthrax spores for potential use as a bioweapon
• At present there is suspicion that research on anthrax is
ongoing by several nations and extremist groups
• One example of this is the release of anthrax spores by
the Aum Shrinrikyo cult in Tokyo in 1993. Fortunately,
there were no casualties associated with this episode.
Anthrax as a Bioweapon II
•
1979: the accidental release of spores into the atmosphere from a Soviet
Union bioweapons facility in Sverdlosk:
– at least 77 cases of anthrax were diagnosed with certainty, of which 66 were fatal
– victims have been exposed in an area within 4 km downwind of the facility
– deaths due to anthrax were also noted in livestock up to 50 km away from the
facility
– interval between probable exposure and development of clinical illness ranged from
2 to 43 days (the majority of cases were within the first 2 weeks)
– death typically occurred within 1 to 4 days following the onset of symptoms
– the anthrax spores can lie dormant in the respiratory tract for at least 4 to 6 weeks
•
September 2001: anthrax spores delivered through the U.S. Postal System.
– CDC identified 22 confirmed or suspected cases of anthrax (11 patients with
inhalational anthrax, of whom 5 died, and 11 patients with cutaneous anthrax - 7
confirmed - all of whom survived)
– cases occurred in individuals who opened contaminated letters as well as in postal
workers involved in the processing of mail
– one letter contained 2 g of material, equivalent to 100 billion to 1 trillion spores
(inoculum with a theoretical potential of infecting up to 50 million individuals)
– The strain used in this attack was the Ames strain - was susceptible to all
antibiotics
Bacillus anthracis
• Aerobic, sporing Gram-positive rod:
infection usually transmitted by spores
• Generally more sensitive to antibiotics
than other Bacillus species, but multi drug
resistant strains have been found in nature
• BUT not sensitive to 3rd generation
cephalosporins
• Easily dismissed as a contaminant when
identified in general hospital laboratories
B.anthracis, forming spores
Typical, wavy chains of bacilli, appearance like railway trucks
B. anthracis toxins
• Lethal toxin (LeTx): intracellular
endopeptidase, probably directly damages
endothelial cells; also immunosuppressive.
• Oedema toxin (ETx): potent adenyl
cyclase; contributes to shock and
potentiates LeTx.
• Protective antigen: the portion of the
binary LeTx and ETx complexes which
mediates attachment to target cells
Bacillus anthracis: epidemiology
• Spores of B. anthracis are widely dispersed in
nature: in soil, animal carcases and skins, and items
made from skin, wool or hair (eg drums made with
animal skins, bags, fur robes, plaster reinforced with
horse-hair etc)
• It is relatively difficult to infect humans: usually skin
inoculation or a large inhalational exposure is
required
• The organism is therefore classified at biosafety
level 3 (CL 3)
Anthrax presentations
• Inhalational: ‘flu’
followed by
mediastinitis and
pneumonitis
• Cutaneous
• Gastrointestinal
• Meningitic
CUTANEOUS ANTHRAX
Most common presentation:
Look for black eschar; halo of
vesicles; extensive oedema
Cutaneous Anthrax:
Early lesions
(CDC Public Health Image Library)
(courtesy AB Christie, Liverpool)
Cutaneous Anthrax
• 95% of naturally occurring cases
• Subcutaneous inoculation of
spores
• Hands, forearm, head
• Incubation: <1 to 7 days
• Small painless papule  ulcer
with marginal vesicles (24-48h)
• Painless oedema surrounds
lesion
• Develops into eschar (2-6 d)
• Untreated mortality 20%
(treated v. rare)
( CDC. www.bt.cdc.gov/agent/cutaneous.asp)
Cutaneous Anthrax
Note extensive oedema in relation to lesion size
( CDC www.bt.cdc.gov/agent/cutaneous.asp)
Cutaneous Anthrax:
Differential Diagnosis
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Necrotic ulcers
Rickettsial eschar
(e.g. tick typhus)
Pox virus infection
(e.g. cowpox, orf)
Spider bites
Cowpox
(courtesy Dr D. Baxby, Liverpool)
Cutaneous anthrax:
oedema
• Rarely,
bacteraemia can
accompany
cutaneous
anthrax
• Always
investigate, and
treat sepsis with
high-dose IV
antibiotic
Intestinal Anthrax
• Ingestion of contaminated
meat
• Incubation: <1 - 7 days
• Fever, acute abdomen,
vomiting, bloody diarrhoea
• Intestinal eschar (similar to
cutaneous lesion)
• Progression to sepsis
syndrome
• Mortality 50 - 100% despite
treatment
(Armed Forces Institute of Pathology, USA)
Inhalational anthrax
• Flu’-like onset, respiratory
failure develops abruptly
after 3-4 days-fatal in 1 or
2 days
• CXR suggestive, but
features can be subtle
• Blood cultures pos.(CL3)
• PCR possible (ref.lab)
• responds to early
vigorous treatment
Jernigan et al. EID 2001; 7: 933
Confirmed anthrax cases associated with bioterrorism: U.S., 2001.
A. Geographic location and clinical manifestation of the 11 cases of
confirmed inhalational and 7 cases of confirmed cutaneous anthrax.
B. Epidemic curve for the 18 confirmed cases of inhalational and
cutaneous anthrax and 4 cases of suspected cutaneous anthrax.
Progression of chest x-ray findings in a patient with inhalational anthrax.
Findings evolved from subtle hilar prominence and right perihilar infiltrate
to a progressively widened mediastinum, marked perihilar infiltrates,
peribronchial cuffing, and air bronchograms.
Recognising inhalational
anthrax
• 10 cases of inhalational anthrax: USA
• WCC 7.5-13.3 x109/l (6 < 10.0)
• 6/6 had >70,000 RBCs in pleural fluid, with
high protein and low WBCs
• 6/6 had PaO2 80mmHg or less on air
• 5/7 treated within 5 days of onset survived
• 1/3 treated after 5 days survived
JA Jernigan et al. EID 2001; 7: 933
Treating inhalational anthrax
• Severe chest
infection of
unknown cause.
• DON’T use 3rd gen.
Cephalosporin alone.
• Use a penicillin eg.coamoxyclav plus a
macrolide/ciproflox.
• Or add gentamicin.
• Antibiotics effective
for anthrax.
• Ciprofloxacin.
• Benzyl penicillin.
• Macrolides.
• Gentamicin (plus
pen.).
• Doxycycline.
• Chloramphenicol.
Vaccination and Prevention
• The first successful vaccine for anthrax was developed
for animals by Louis Pasteur in 1881.
• At present, the single vaccine licensed for human use is
a product from the cell-free culture supernatant of an
attenuated, nonencapsulated strain of B. anthracis
(Stern strain) - anthrax vaccine adsorbed (AVA).
• Clinical trials for safety in humans and efficacy in
animals are currently under way to evaluate the role of
recombinant protective antigen (one of the major
components, along with lethal factor and edema factor,
of B. anthracis toxins) as an alternative to AVA.
• The efficacy of AVA in a postexposure setting in humans
has not been established.
• The current recommendation for postexposure
prophylaxis is 60 days of antibiotics (ciprofloxacin or
doxycycline).
Chemo-prophylaxis of
anthrax
Prophylaxis
Adult doses
Child doses
Ciprofloxacin
500mg orally bd 20-30mg/kg bd
for 6 weeks
Doxycycline (if 100mg orally bd 5mg/kg orally in
cipro x tolerated
two divided
/indicated)
doses
Although normally used with caution or contraindicated,
these drugs may be given in pregnancy, lactation and
childhood to protect against anthrax
PLAGUE
MICROBIOLOGICAL FEATURES:
gram-negative, rod-shaped, facultative anaerobic
bipolar staining, non-motile, non-sporulating
BIOLOGICAL SURVIVAL:
15 minutes in 55° C/ few hours in sunlight
weeks in water, grains, moist soil, dry sputum, flea feces
lives months/years at just above 0°C
HOST RANGE:
zoonotic disease of rodents:
intracellular organism:
rats, mice, ground squirrels
monocytes/macrophages
=> long-term survival requires host
=> Circumstances for natural human outbreaks:
disasters/ disruption of rat habitats/ rat dis- or relocation
SYNDROMIC PRESENTATION – SESSION 1
PLAGUE
EPIDEMIOLOGY I
Since 1965:
NATURALLY OCCURING PLAGUE
approximately 1500 cases/year
25 countries reported cases
50% Eastern and South Africa, esp. Madagascar
1980-1994:
18,739 cases reported from 20 countries to WHO
2000 – 2005:
December 2007:
Zambia, Algeria, Malawi, DR Congo
n=1, marmoth hunter, China
Endemic in U.S.
1947-96:
1970-2003:
83%
15%
2%
390 cases/y
5-15 cases/y
Bubonic
Septicemic
Primary Pneumonic
SYNDROMIC PRESENTATION – SESSION 1
PLAGUE
TRANSMISSION
4 ROUTES FOR HUMAN INFECTION
1.
Flea-bite (most common)
=> Rat-borne urban epidemics in history
=> Human overcrowding, indoor contacts
2.
Handling infected animals (skin contact, scratch, bite)
=> Endemic sylvatic plague with sporadic outbreaks
=> Occupational risks
3.
Inhalation of contaminated aerosol (human/animal)
=> Only pneumonia capable of person to person spread
4.
Ingestion of infected meat
SYNDROMIC PRESENTATION – SESSION 1
PLAGUE
CLINICAL COURSE I
3 TYPES OF DISEASE
Bubonic
Septicaemic
Pneumonic
Plague: Clinical Forms
Bubonic
• Common form of naturally
occurring plague, following bite
of infected flea
• Inguinal, axillary, or cervical
lymph nodes are the most
commonly affected
• 80% can become
bacteraemic
• 60% mortality if untreated
(CDC image library)
SYNDROMIC PRESENTATION – SESSION 1
PLAGUE
CLINICAL COURSE II
1. “CLASSIC” Bubonic Plague
ENTRY:
Bite of infectious flea
Contact/ ingestion of infected animals
Contact/ ingestion of infectious material
BUBOES:
Enlarged tender lymphnodes (unilateral)
Usually inguinal/ femoral in adults
Cervical/ submaxillary common < 10y
CFR:
40-60% untreated, <5% treated
Overall 14% in U.S. (delayed diagnosis/ therapy)
COMPLICATION:
BACTERAEMIA
secondary septicaemic plague
secondary pneumonic plague
secondary plague meningitis
www.cdc.gov
3. Pneumonic Plague
US cases:
2%
12%
PRIMARY PNEUMONIC
SECONDARY PNEUMONIC
PRIMARY:
Result of droplet inhalation
Only few cases in endemic areas
ENTRY:
Aerosol => other patients/ infected animals/ BW
SECONDARY:
Hematogenously spread to lungs
Initially: interstitial pattern/ later: abscess
CFR:
~ 100% if untreated/ therapy delayed > 18-24h after onset
Remains high despite treatment:
Overall 57% (U.S.)
DEATH WITHIN 2-4 DAYS (max 6d): cyanosis, stridor, resp. failure
Plague: Differential Diagnosis
Pneumonic
• Bioterrorism threats
• Anthrax
- Tularaemia
- Melioidosis
Bubonic
• Staph/strep adenitis
• Glandular tularaemia
• Other pneumonias,
esp. “atypicals”
Septicaemic
• Other Gram-negative
sepsis
• Meningococcaemia
• Rickettsia
• Leptospirosis (haemorrhagic)
• Cat scratch disease
• LGV & chancroid
SYNDROMIC PRESENTATION – SESSION 1
PLAGUE
TREATMENT
FIRST LINE:
STREPTOMYCIN
CHILDREN:
ADULTS:
=>bacteriocidal
30 mg/kg IM divided q8-12h (max 2g/day)
1g IM bid
GENTAMYCIN
CHILDREN:
ADULTS:
=> as effective, qd dosage
2.5mg/kg im/iv q8h
5mg/kg iv qd (check levels) OR
load 2mg/kg, then 1.7mg/kg q8h
SECOND LINE:
DOXYCYCLIN
=> good in vitro + good human data
1. Single 200mg iv loading dose
2. 100mg iv bid or 200 mg iv qd adults/ kids >45kg
=> 1st choice po therapy for mass casualties/ PEP
Smallpox
The variola virus
• A member of the family of Orthopoxviridae
• The largest viral genome: double-stranded
DNA
• An enveloped virus, but the envelope is
not essential for infectiousness
The Yugoslavia outbreak 1972
• Single index case spent time in Iraq
– 11 contacts developed smallpox
• 100 secondary cases in contacts and
other hospital patients
• 14 tertiary cases
• Spread to other cities
• Total 175 cases, 35 deaths
Variola: first and second day of
rash (4th-5th day of fever)
Variola: 4th day of rash
•For the first time-on
the fourth day of the
rash and the fifth day
of infectiousness, a
typical vesicular
appearance is seen
Variola major: drying rash (7-9
days)
•The rash is
becoming less
infectious
•Conjunctival
lesions are usually
benign and heal
completely
Variola major: confluent on day
7 of rash
Variola major: scabbing of rash:
day 11
Smallpox Clinical Course
• Prodrome (day 13)
• Erythematous
rash (days 2-3)
• Maculopapular
rash (days 4-6)
• Vesicular 
pustular rash (days
8-14+)
(Fenner F et al. Smallpox and its eradication. WHO 1998.
http://whqlibdoc.who.int/smallpox/9241561106.pdf )
Variola major: variation in
severity
Boys aged 13 years, infected from the same source-admitted same day:
right-unvaccinated; left-vaccinated in infancy
Diagnosis of smallpox:
(must be in CL4 facility)
• Classical tests
EM of vesicle fluid for
poxvirus
Virus culture
(CFT and ELISA for plasma
antibodies-not reliable)
PCR: rapid,
specific, can
distinguish
between
poxvirusesperformed on
blood or vesicle
fluid
Smallpox vs. Chickenpox
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Smallpox
Incubation 7-17d
Severe illness
Prodrome
Headache and back pain
Centrifugal
Synchronous
Rash not initially itchy
Lesions round
Scabs form 10-14d
Scabs separate 14-28d
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Chicken pox
Incubation 14-21 d
Usually mild
Prodrome
Mild malaise
Centripetal
Asynchronous
Rash initially itchy
Lesions oval
Scabs form 4-7d
Scabs separate <14d
Management of smallpox
• General supportive measures
• Analgesia (the rash is very painful)
• Good hygiene (secondary infection is a
danger-the skin is a common portal of
entry)
• Antibiotics to treat secondary infection and
limit scarring
• ?antiviral drugs
Smallpox vaccine
• Live vaccinia vaccines
 Lister-Elstree
 NYCBH
 2nd generation live
 (Modified vaccinia and others)
• Given by scarification
MELIOIDOSIS
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Burkholderia pseudomallei
Aerobic, gram-negative, motile bacillus
Found in water and moist soil
Opportunistic pathogen
Produces exotoxins
Can survive in phagocytic cells
• Latent infections common
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS V
Epidemiology II
disease of rice farmers
endemic in tropics and subtropics:
Southeast Asia, Australia, the Middle East, India, China,
Caribbean
U.S. and EU cases linked with travel abroad
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS VI
Epidemiology III
Clinical disease uncommon
in endemic areas
– antibodies in 5-20% of
agricultural workers
– no history of disease
Seasonal increase (wet season)
– heavy rainfall
– high humidity or temperature
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS VIII
Transmission
WOUND INFECTION
– Contact with contaminated soil
or water
INGESTION
– Contaminated water
INHALATION
– Dust/ contaminated soil
RARELY
– Person-to-person
– Animal-to-person
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS IX
Clinical Course I
INCUBATION PERIOD:
1-21 days (~ 9 days) up to 30 years
Always Fever, chills, malaise
Soft tissue:
Pulmonary:
Septicaemic/disseminated:
Abscess
Productive cough, dyspnoea
Multiple abscesses, Septic shock
MOST INFECTIONS ASYMPTOMATIC/ LATENT
MODE OF TRANSMISSION INDUCES DIFFERENT CLINICAL FORMS:
INOCULATION =>
INHALATION =>
Focal (wound) infection
Acute pulmonary infection
Both can result in secondary SEPTICEMIA
CNS involvement is rare
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS X
Clinical Course II
FOCAL INFECTIONS
Abscess/ granuloma formation
– Skin
– Bone and/or muscle
– Joints
– Internal organs
– Genitourinary
– Nervous system (infrequent)
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS XI
Clinical Course III
ACUTE PULMONARY INFECTION
Most common form:
High fever, headache
Dull aching chest pain
Cough, tachypnea, rales
Chest X-rays
– Upper lobe consolidation
– Nodular lesions
– Pleural effusion
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS XII
Clinical Course IV
PULMONARY INFECTION - RADIOLOGY FINDINGS
USE CT
IF AVAILIABLE !
SYNDROMIC PRESENTATION – SESSION 1
MELIOIDOSIS XIV Diagnosis and prevention
DIAGNOSIS:
Clinical suspicion
=> travel to endemic areas
low budget, outdoor travel
=> occupational exposure
medical, military
Microbiology
=> Isolation of organism
=> Various serological tests
PREVENTION
Avoid contact with soil/water => Chlorination if needed
Handling infected animals with care
Thorough cleaning of wounds