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Module 7: Multisystems > Agents of bioterrorism II > Flashcards

Agents of bioterrorism II Flashcards

1
Q

What are the characteristics of bacillus?

A

Gram +

Aerobic or Facultatively Anaerobic

Spore forming rods

Most species are opportunistic pathogens of low virulence

Two species cause disease: cereus (food poisoning) and anthracis (anthrax)

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2
Q

How does spore-forming ability help bacillus?

A

Spores are formed in soil and are very resilient and infectious

  • Heat resistance
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3
Q

What are the virulence factors of Bacillus anthracis?

A

Capsule: poly D-glutamic acid
(hallmark of anthracis)

Toxins:
Edema toxin = EF+PA
Lethal toxin = LF+PA

PA = protective antigen = B subunit (cell binding component) for both toxins
–> anti-PA Abs neutralize toxins

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4
Q

What is Edema Factor?

A

A virulence factor of Bacillus anthracis

It is a calmodulin-dependent bacterial adenylate cyclase

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5
Q

What is Lethal Factor?

A

A virulence factor for Bacillus anthracis

It is a zinc-metaloprotease that cleaves mitogen activated protein kinase kinase (MAPKK) and inhibits MAPK signal transduction pathways in macrophages

*What makes anthrax lethal

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6
Q

What is the reservoir for Bacillus anthracis?

A

Reservoir: Soil

–> Herbivores infected during grazing
- Human transmission by:
Contact with infected animals, hides, hair, wool, bone, bone products, biting flies
Ingestion of contaminated meat
Inhalation

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7
Q

What are the forms of anthrax?

A

Cutaneous - most common in nature

Gastrointestinal

Inhalation - Woolsorter’s disease, bioterrorism

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8
Q

What is the presentation of cutaneous anthrax?

A

Produces a papule that progresses to central necrosis to black eschar

  • Painless
  • Edema occurs
  • 80-90% complete resolution
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9
Q

What is the presentation of GI anthrax?

A

RARE!

  • Follows ingestion of spore-contaminated meat

- Ulcers form at site of invasion (i.e. mouth, esophagus, intestine) which leads to
Regional lymphadenopathy
Edema
Sepsis

Mortality >50%

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10
Q

What is the presention of inhalational anthrax?

A

Non-specific symptoms for 3-5 days

Terminal phase:
Dyspnea
Stridor
Cyanosis
Increased chest pain
Chest wall edema
Shock and death within 24-36hrs
Hemorrhagic mediastinitis, hemorrhagic pleural effusions (seen on CXR)

  • Can cause meningitis and GI hemorrhage
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11
Q

What is the CDC treatment for inhalational anthrax?

A

Combination Abx Therapy:

Ciprofloxacin or Doxycyclin

+

Clindamycin

+

Rifampin

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12
Q

What are the characteristics of Yersinia pestis?

A

Agent of bubonic plague

Gram - rod

Grows well on MacConkey’s agar

Flea vector requried for transmission
(exception: pneumonic plague)

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13
Q

What is the pathogenesis of Yersinia?

A

Flea bites and regurgitates bacteria –> Vesicular lesions at bite site –> Organism is phagocytosed by PMNs and Monocytes

Either Killed in PMNs
or
Released from monocytes
–> can now resist phagocytosis by both PMNs and monocytes –> goes to lymphatics –> localizes in regional lymph nodes and creates bubo

May Disseminate to bacteremia (–> pneumonia, meningitis, and/or septic shock)
or
Stop

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14
Q

How is plague diagnosed?

A

Culture on MacConkey’s agar or sheep blood agar

Drops of bubo aspirate, blood, or other materials used for staining

  • -> Gram stain shows PMNs and Gram- coccobacilli
  • -> Wayson stain shows light blue bacilli wiht dark blue polar bodies
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15
Q

What makes a virus a High priority for biodefense agent?

A

Pose a risk to national security because they:

  • Can be easily disseminated or transmitted person-to-person
  • High mortality
  • Might cause public panic and social disruption
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16
Q

What is hemorrhagic fever?

A

Acute febrile illness characterized by malaise, myalgia, and prostration dominated by general abnormalities of vascular permeability, and regulation.

Bleeding manifestations often occur, usually diffuse and reflect widespread vascular damage rather than life-threatening volume loss

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17
Q

What are the virus families containing VHF agents?

A

Arenaviruses:
Lassa fever
S. American Hemorrhagic fevers

Bunyaviruses:
Congo-crimean hemorrhagic fever (CCHF)
Rift Valley Fever (RVF)
Hantaviruses

Filoviruses:
Ebola
Marburg

Flaviviruses:
Yellow-fever
Kyasanur Forest disease
Omsk hemorrhagic fever

18
Q

What are the properties of Viral Hemorrhagic Fevers?

A

All enveloped, DNA viruses

  • Survival is dependent on animal or insect reservoir
  • -> Human infection is incidental to interaction with host
  • Outbreaks occur sporadically and irregularly
  • No cure or established drug treatment
19
Q

What are key factors in the patient history of viral hemorrhagic fever?

A

Foreign travel to endemic or epidemic area

Rural environments

Possible nosocomial exposure

Contact with arthropod or rodent reservoir

Domestic animal blood exposure

20
Q

What is the treatment for viral hemorrhagic fever?

A

Supportive care

Cautious sedation and anagesia use

Correct coagulopathies as needed

No anti-platelet drugs or IM injections!

Ribavirin possibly effective for:
Arenaviruses
Bunyaviruses

21
Q

What are characteristics of Filoviruses?

A

Examples: Ebola and Marburg

Structure:
Pleomorphic
long, sometimes branched filaments
Shorter filaments shaped like a “6” or “U” or circles

  • *Enveloped**
  • *Single-stranded, negative-sense RNA**

New viral particles created by budding from surface of host cells (hence, enveloped)

22
Q

What is the natural reservoir of ebola virus?

A

likely Bats

23
Q

What are the subtypes of ebolavirus?

A
  1. Ebola-Zaire
  2. Sudan
  3. Ivory Coast
  4. Bundibugyo (causes disease in humans)
  5. Ebola-Reston (causes disease in non-human primates)
24
Q

What is the natural reservoir for Marburg virus?

A

Fruit bats

25
Q

How is Ebola virus transmitted?

A

By direct contact wiht blood and secretions of an infected person, and through contaminated needles, etc.

–> Nosocomial transmission occurs frequently during outbreaks

**There are no carrier states with Ebola virus - All infections are acute

26
Q

How is Ebola virus diagnosed?

A

Difficult in early stages because of non-specific early symptoms (red eyes, skin rash, etc)

Early days: ELISA, IgM ELISA, PCR, virus isolation

Post-mortem: Immunohistochemistry, virus isolation, PCR

27
Q

What are characteristics of Crimean-Congo Hemorrhagic fever?

A

Transmitted by ticks; responsible for severe outbreaks in humnas; not pathogenic for ruminants

Bunyavirus:
Genome is circular
Ambisense RNA (+ and -) in three parts:
Small (S), Middle (M), Large (L)

28
Q

What are the Arenavirus hemorrhagic fevers in humans?

What are their characteristics?

A

Lassa fever and S. American hemorrhagic fever

Rodent-borne disease- contact with rodent excreta causes aerosol transmission

Enveloped virus
Grainy appearance caused by ribossomes from host cells
Ambisense RNA

29
Q

What are characteristics of Lassa virus?

A

Arenavirus

Rodent reservoir (Mastomys species): transmitted through excreta inhalation, consumption, or bite

Secondary human-to-human transmission with occasional nosocomial outbreaks
- contact with blood or body fluids

Affects all ages and sexes; less sever in younger patients

Most serious in pregnant women (more susceptible and causes abortion)

30
Q

What is the presentation of Lassa Virus?

A

Symptoms occur 1-3 weeks after infection:

Fever
Retrosternal pain
sore throat
Back pain
cough
Abdominal pain
Vomiting
Diarrhea
Conjunctivitis
Facial swelling
Proteinuria
Mucosal Bleeding
Hearing loss
Tremors
Encephalitis

  • Due to varied, nonspecific presentation, clinical diagnosis is difficult
31
Q

What is “Swollen Baby Syndrome”

A

Lassa fever in children and infants:

Edema
Abdominal Distention
Bleeding
Poor Prognosis

32
Q

What is treatment for Lassa Fever?

A

Supportive!

Ribavirin: effective against Lassa

Hyperimmune serum: effects still uncertain although dramatic results have been reported

33
Q

How is Lassa diagnosed?

A

ELISA to detect IgM and IgG antibodies as well as Lassa antigen

Culture

Immunohistochemistry on post-mortem diagnosis

34
Q

How is lassa fever prevented?

A

No vaccine

Rodent control

35
Q

What are characteristics of Hendra and Nipah viruses?

A

Paramyxoviruses

Zoonotic and highly pathogenic

Broad tropism: ephrin B2/B3 as receptors

BSL04 restricted

Glycoprotein spikes useful for Antibodies and may make vaccination a future possibility

36
Q

What is the presentation of Nipah/Hendra infection?

A

Widespread, multisystemic vasculitis
- thrombosis, ischemia and necrosis

Most severe clinical and pathologic manifestations in brain, lungs, and spleen

Severe respiratory disease - “ARDS-like”
(pneumonitis/multi-organ failure and/or acute encephalitis)

37
Q

What are characteristics of poxviruses?

A

Large (seen by light-microscope)

Outer lipoprotein envelope that encloses dumbell shaped core

Genome: Large, double-stranded linear DNA
Replicates in cytoplasm

Very resistant to inactivation viable in crusts for years at room temperature

38
Q

What makes a virus suitable for eradication?

A

No animal reservoir

Lack of recurrent infections

One or few stable serotypes

Availability of an effective vaccine

Absence of subclinical infections

39
Q

What are characteristics of Smallpox?

A

Disfiguring disease with high mortality

spread by secretions from mouth and nose and by material from pocks or scabs

Transmission requires close contact

Every vesicular lesion is at same stage (chickenpox and others have lesions at different stages at all times)

40
Q

What is the distribution of smallpox lesion?

A

Denser on face, arms, hands, legs, and feet than body

Involvement of palms and soles

41
Q

How is smallpox diagnosed?

A

Smear from lesions - stained with gentian violet; look for Guarnieri bodies

Electron microscopy of lesion material showing cytoplasmic inclusions and brick-shaped virions

Egg inoculation results in specific pock morphology on chorioallantoic membranes

PCR

42
Q

What are complications from smallpox vaccine?

A

Generalized vaccinia

Eczema vaccinatum

Post-vaccination encephalitis

Progressive vaccinia

Overall fatality

Module 7: Multisystems (13 decks)

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