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Faith's Multisystems module > Anthrax, Plague, Viruses > Flashcards

Anthrax, Plague, Viruses Flashcards

1
Q

Anthrax: Gram +/-? Aerobic/anaerobic? Spore/non-spore former? Cocci/rods? How does it appear on the microscope?

A 
Gram +
Aerobic/facultative anaerobic
Spore forming
Rod
Forms long filaments/chains
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2
Q

What type of diseases can Bacillus cause?

A

Cereus (food poisoning)

Anthracis: anthrax.

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3
Q

Virulence factors of Bacillus anthracis? Toxins?

A
  • CAPSULE: Poly D-glutamic acid (unique!!! different from the polysaccharide capsule of others)
  • Edema toxin (A subunit)
  • Lethal toxin (A subunit)
  • Protective antigen (B subunit - binds cell)
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4
Q

What is edema factor

A

A calmodulin dependent bacterial adenylate cyclase: increases cAMP resulting in edema.

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5
Q

What is lethal factor

A

A zinc-metaloprotease that cleaves mitogen activated protein kinase kinase (MAPKK) => inhibits signal transduction pathway in macrophages.

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6
Q

What is protective antigen? How does it work?

A

Protective antigen binds to cell, forming a 7-mer or 8-mer - then EF or LF binds to it and can enter the cell.

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7
Q

Where is the reservoir of anthrax?

A

Soil

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8
Q

What are the disease forms of anthrax?

A
  1. Cutaneous: forms a painless black eschar with edema. MOST COMMON. 80-90% complete resolution.
  2. Gastrointestinal: RARE. Causes ulcers at site of invasion = hemorrhage.
  3. Inhalational: incubates 1-43 days, results in nonspecific symptoms for 3-5 days. defined by HEMORRHAGIC MEDIASTINITIS
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9
Q

How do you treat anthrax?

A

60 day regiment:
ciprofloxacin or doxycycline
+ clindamycin
+ rifampin

antibodies do not kill the spore = thus the long treatment

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10
Q

What is the vaccine for anthrax?

A

Biothrax
Inactivated vaccine of protective antigen (PA)

one intramuscular dose at 0, 4 weeks, then 6, 12, 18 months.
Requires yearly boosts

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11
Q

What is the bug that causes bubonic plague?

A

Yersinia pestis

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12
Q

Yersinia pestis: Gram +/-, cocci/rod? What does it grow on? what can you stain it with to confirm diagnosis?

A

Gram - rod, grows well on MacConkey’s agar.

Stains with Wayson stain = appears light blue bacilli with darl blue polar bodies (fluorescent)

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13
Q

What is the mode of transportation of yersinia pestis?

A

flea - except for pneumonic plague.

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14
Q

What are the viral agents that are listed in Category A of bioterrorism?

A

Smallpox

viral hemorrhagic fevers (filoviruses - ebola/marbur and Arenaviruses like Lassa Fever)

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15
Q

What is the viral agent that is listed Category B of bioterrism?

A

Viral encephalitic agents (alphaviruses such as VEE)

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16
Q

What are the viral agents that are listed in Category C?

A

These are emerging pathogens:

  • henipaviruses (nipah virus, hendra virus)
  • tick-borne encephalitis virus
  • Tick-borne hemorrhagic fever viruses such as Crimean-congo Hemorrhagic fever
  • Yellow Fever
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17
Q

What is Viral Hemorrhagic Fevers?

A

These groups of illnesses causes overall damage to the vascular system, resulting in hemorrhage.

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18
Q

What are the common presenting signs of a viral hemorrhagic fever?

A
  • malaise
  • myalgia
  • prostration
  • bleeding = lots of bruises. More vascular damage than life-threatening volume loss.
19
Q

What are some examples of viruses that can cause viral hemorrhagic fever?

A

Arenaviruses: Lassa Fever
Bunyaviruses: CCHF, Hantavirus
Filovirus: Ebola, Marburg
Flavavirus: Yellow Fever

20
Q

What are the properties of viruses that cause viral hemorrhagic fevers? eg - type of virus? reservoir? location? cure/treatment?

A
  • they are all enveloped RNA viruses
  • Thus, their survival is dependent on a host
  • they are generally geographically restricted based on their host
  • There is no cure or establised drug treatment
21
Q

What are the differential diagnosis of a viral hemorrhagic fever?

A 
consider Bacterial (tyhoid fever, rickettsiosis), 
Protozoa (falciparum malaria), Others: (HUS, heat stroak, vasculitis).
22
Q

What is the typical patient history of a patient with viral hemorrhagic fever?

A
  • foreign travel to endemic/epidemic areas
  • rural environments
  • contact with arthropod or rodent reservoir
  • domestic animal blood exposure
23
Q

What are some treatments for patients presenting with viral hemorrhagic fever?

A

SUPPORTIVE CARE

  • coagulopathies?
  • Ribavirin - only for arenaviruses and bunyaviridae (CCHF, Hantavirus, RVF). Tpically used for HCV and for RSV.
24
Q

which viruses that cause VHF currently have vaccines?

A
  1. Yellow Fever: Yellow fever 17D

2. Argentine hemorrhagic fever/Junin virus: Candid #1

25
Q

Filoviruses: Ebola/Marburg. What are the key structural elements?

A

-SSRNA enveloped viruses that appear filamentous and CURLY

26
Q

What is the natural reservoir of ebola?

A

Bats, mostly seen in Africa

27
Q

Crimean-congo hemorrhagic fever (CCHF): transmission?

A

TICKS

28
Q

Crimean-congo hemorrhagic fever (CCHF): key structural elements?

A

This is a bunyavirus: circular genome, ambisense RNA (+ and -) divided into three parts small, meddle, and large.

29
Q

Arenaviruses: Lassa fever and S. american Hemorrhagic fevers. How are these transmitted?

A

RATS: contact with rat excretia, ingestion of contaminated food, direct contact with broken skin, inhalation of tiny particles.

30
Q

Arenaviruses: Lassa fever and S. American Hemorrhagic fevers: how do these appear microscopically?

A

grainy appearance due to presence of ribosomes from their host cells (arena = sandy in latin).

31
Q

Symptoms of Lassa Fever

A

Flu-like symptoms, HEARING LOSS, facial swelling, sore throat, v/d - varied and nonspecific symptoms. Death rates higher in pregnant women especially in third trimester (Lassa virus also causes abortions) “SWOLLEN BABY SYNDROME”

32
Q

Treatment of Lassa fever

A

Ribavirin

Hyperimmune serum

33
Q

Prevention of Lassa fever

A

RODENT CONTROL

no vaccine available.

34
Q

Paramyxoviruses: Hendra and Nipah viruses: what animals? What receptors are used to enter the cells?

A

This is a zoonotic and highly pathogenic virus that originates from bats but can infect pigs, horses, dogs, cats, hamsters, ferrets, monkeys and humans.

These have a broad tropism: ephrin B2/B3 as receptors

35
Q

What are the symptoms of a Nipah/Hendra infection?

A

Widespread multisystem vasculitis: thrombosis, ischemia, necrosis.

Especially at the brain, lungs and spleen

Can cause a severe respiratory disease (ARDS like?) and/or acut encepahalitis.

Bloody froth at the mouth

36
Q

Poxviruses: how does this appear microscopically?

A

LARGE - can see with simple light microscopy as a brick-shaped particle. Has a complex outer envelope.

37
Q

What are the structural properties of Poxviruses?

A

LARGE - complex outer shell, with DNA virus that REPLICATED IN THE CYTOPLASM. It is very resistant to inactivation (can remain viable in crusts for years at room temperature)

38
Q

How did ppl in the past become immunized to smallpox?

A

they got cowpox! “Fair as a milkmaid” = would get a small pox on their fingers, but be immune to smallpox

39
Q

How are we able to eradicate smallpox from the US?

A

Because:

  1. there is no animal reservoir
  2. there are very few sterotypes
  3. there is an effective vaccine
  4. There is no subclinical infection
40
Q

What are the clinical signs of smallpox? verses chicken pox?

A

First fever, then 2-4 days after, rash appears - papules => fluid filled vesicles. All of these papules will be at the same stage of development (different from chicken pox where pustules can be at different stages).

41
Q

Small pox can appear all over the body, but will favor which part of the body? compared to chickenpox?

A

Smallpox pustules are denser on the face, arms, hands, legs and feet rather than the trunk/body. Involves the palms and soles.

Chickenpox rarely involves the hands/sole of feet.

42
Q

How do you diagnose chickenpox? what are the key microscopic features you look for?

A

Stain with gentian violet = look for GUARNIERI BODIES (typical inclusion bodies)

Electron microscopy: Shows cytoplasmic inclusions and brick shaped virions

Egg inoculation: shows specific pock morphology on chorioallantoic membranes

PCR.

43
Q

What are some complications of the smallpox vaccine?

A

can auto-inoculate (touch pox vaccine => eye = BAD)

can have generalized vaccinia (body wide dermatitis reaction instead of one pox rnx), eczema vaccinatum (seen in ppl with chronic granulocytic leukemia - spreading red rash from vaccine site) , post-vaccination encephalitis, etc.

Faith's Multisystems module (12 decks)

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