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

• 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:

– 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)

• 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 ANTHRAXMost common presentation:Look for black eschar; halo ofvesicles; extensive oedema

Cutaneous Anthrax: Early lesions

(CDC Public Health Image Library)

(courtesy AB Christie, Liverpool)

Cutaneous Anthrax

( CDC. www.bt.cdc.gov/agent/cutaneous.asp)

• 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)

Cutaneous Anthrax

Note extensive oedema in relation to lesion size

( CDC www.bt.cdc.gov/agent/cutaneous.asp)

Cutaneous Anthrax: Differential Diagnosis

• 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

(Armed Forces Institute of Pathology, USA)

• 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

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.co-amoxyclav 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 ofanthraxProphylaxis Adult doses Child doses

Ciprofloxacin 500mg orally bd for 6 weeks

20-30mg/kg bd

Doxycycline (if cipro x tolerated /indicated)

100mg orally bd 5mg/kg orally in two divided 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: rats, mice, ground squirrels

intracellular organism: monocytes/macrophages

=> long-term survival requires host

=> Circumstances for natural human outbreaks:disasters/ disruption of rat habitats/ rat dis- or relocation

SYNDROMIC PRESENTATION – SESSION 1PLAGUE EPIDEMIOLOGY INATURALLY OCCURING PLAGUE

Since 1965: 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: Zambia, Algeria, Malawi, DR Congo

December 2007: n=1, marmoth hunter, China

Endemic in U.S. 1947-96: 390 cases/y1970-2003: 5-15 cases/y

83% Bubonic15% Septicemic2% Primary Pneumonic

SYNDROMIC PRESENTATION – SESSION 1PLAGUE 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

3 TYPES OF DISEASE

Bubonic

Septicaemic

Pneumonic

SYNDROMIC PRESENTATION – SESSION 1PLAGUE CLINICAL COURSE I

Plague: Clinical FormsBubonic

(CDC image library)

• 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

SYNDROMIC PRESENTATION – SESSION 1PLAGUE CLINICAL COURSE II1. “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% treatedOverall 14% in U.S. (delayed diagnosis/ therapy)

COMPLICATION: BACTERAEMIA

secondary septicaemic plague

secondary pneumonic plaguesecondary plague meningitis

www.cdc.gov

3. Pneumonic Plague

US cases: 2% PRIMARY PNEUMONIC12% SECONDARY PNEUMONIC

PRIMARY: Result of droplet inhalation Only few cases in endemic areas

ENTRY: Aerosol => other patients/ infected animals/ BW

SECONDARY: Hematogenously spread to lungsInitially: interstitial pattern/ later: abscess

CFR: ~ 100% if untreated/ therapy delayed > 18-24h after onsetRemains 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

• Other pneumonias,esp. “atypicals”

• Leptospirosis (haemorrhagic)

Bubonic• Staph/strep adenitis

• Glandular tularaemia

• Cat scratch disease

• LGV & chancroid

Septicaemic• Other Gram-negative sepsis

• Meningococcaemia

• Rickettsia

SYNDROMIC PRESENTATION – SESSION 1PLAGUE TREATMENTFIRST LINE:

STREPTOMYCIN =>bacteriocidalCHILDREN: 30 mg/kg IM divided q8-12h (max 2g/day)ADULTS: 1g IM bid

GENTAMYCIN => as effective, qd dosageCHILDREN: 2.5mg/kg im/iv q8hADULTS: 5mg/kg iv qd (check levels) OR

load 2mg/kg, then 1.7mg/kg q8h

SECOND LINE:

DOXYCYCLIN => good in vitro + good human data1. Single 200mg iv loading dose2. 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 1-3)• 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 )

Boys aged 13 years, infected from the same source-admitted same day: right-unvaccinated; left-vaccinated in infancy

Variola major: variation in severity

Diagnosis of smallpox: (must be in CL4 facility)

• Classical testsEM of vesicle fluid for

poxvirusVirus culture(CFT and ELISA for plasma

antibodies-not reliable)

PCR: rapid, specific, can distinguish between poxviruses-performed on blood or vesicle fluid

Smallpox vs. Chickenpox

• 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

• 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

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

MELIOIDOSIS

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 1MELIOIDOSIS V Epidemiology II

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 1MELIOIDOSIS VI Epidemiology III

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 1MELIOIDOSIS VIII Transmission

INCUBATION PERIOD: 1-21 days (~ 9 days) up to 30 years

Always Fever, chills, malaise

Soft tissue: AbscessPulmonary: Productive cough, dyspnoeaSepticaemic/disseminated: Multiple abscesses, Septic shock

MOST INFECTIONS ASYMPTOMATIC/ LATENT

MODE OF TRANSMISSION INDUCES DIFFERENT CLINICAL FORMS:

INOCULATION => Focal (wound) infectionINHALATION => Acute pulmonary infection

Both can result in secondary SEPTICEMIACNS involvement is rare

SYNDROMIC PRESENTATION – SESSION 1MELIOIDOSIS IX Clinical Course I

Abscess/ granuloma formation

– Skin– Bone and/or muscle– Joints– Internal organs– Genitourinary– Nervous system (infrequent)

FOCAL INFECTIONS

SYNDROMIC PRESENTATION – SESSION 1MELIOIDOSIS X Clinical Course II

Most common form:

High fever, headache

Dull aching chest pain

Cough, tachypnea, rales

Chest X-rays– Upper lobe consolidation– Nodular lesions– Pleural effusion

ACUTE PULMONARY INFECTION

SYNDROMIC PRESENTATION – SESSION 1MELIOIDOSIS XI Clinical Course III

PULMONARY INFECTION - RADIOLOGY FINDINGS

USE CTIF AVAILIABLE !

SYNDROMIC PRESENTATION – SESSION 1MELIOIDOSIS XII Clinical Course IV

DIAGNOSIS:Clinical suspicion => travel to endemic areas

low budget, outdoor travel

=> occupational exposure

medical, military

Microbiology => Isolation of organism

=> Various serological tests

PREVENTIONAvoid contact with soil/water => Chlorination if needed

Handling infected animals with care

Thorough cleaning of wounds

SYNDROMIC PRESENTATION – SESSION 1MELIOIDOSIS XIVDiagnosis and prevention