Oral Viral Infections Flashcards

1
Q

What are the general characteristics of a virus?

A

 Small- much smaller than bacteria/human cells
 Simple chemical composition- proteins, phospholipids, glycoproteins, nucleic acids (changes depending on family)
 No intracellular organelles- obligate intracellular parasites
 DNA/RNA- can have either

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2
Q

What are examples of DNA/RNA viruses?

A

DNA virus- human herpes

RNA virus- mumps

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3
Q

What are the stages of replication of Herpes Simplex?

A
  1. Binding
  2. Entry into cytoplasm
  3. Release and nuclear transport
  4. Nuclear entry
  5. Gene expression- ribosomes translate viral genes into proteins
  6. DNA replication via viral DNA polymerase
  7. Packaging
  8. Egress via endoplasmic reticulum, golgi apparatus and plamsma membrane
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4
Q

What does 1/2 triangles mean?

A

1- Diagnosis
2- Provisional diagnosis

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5
Q

How is a viral sample taken?

A

Use viral swab- flocked

Place in molecular sample solution- extracts viral DNA/RNA

After immersion- remove swab

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6
Q

What is used when taking a blood sample to check for viruses?

A

EDTA- purple topped
-> used in serology and molecular detection of viral DNA/RNA

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7
Q

What information should be included in virology request form?

A

Pt details & clinician details (inc phone no.)

Clinical details & diagnosis

Date of onset

Patient DOB or CHI number

Specify test (do not request “viral screen”)

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8
Q

What is a maculo-papular rash?

A

Red flat area on the skin covered with bumps (macules/Papules)

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9
Q

Which viruses can cause a macula-papular rash?

A

Enterovirus

HHV6

HHV7

Measles

Rubella

*B19, CMV, EBV- require serology for detection using EDTA blood sample

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10
Q

What is a vesicle?

A

Fluid filled blister

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11
Q

Which viruses are associated with vesicular lesions?

A

HSV1

HSV2

VZV

Enterovirus

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12
Q

What is an ulcer?

A

break in bodily membrane

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13
Q

Which viruses are associated with causing ulcers?

A

HSV

Enterovirus

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14
Q

What specimen/test is required for detecting the cause of macula-papular rashes, vesicular lesions and ulcers?

A

Specimen- mouth swab

Test- RNA/DNA detection

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15
Q

What is serology used for?

A

Detect presence of antibodies against a virus?

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16
Q

Which viruses can be diagnosed from presence of IgM antibodies?

A

CMV

EB

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17
Q

Which viruses can be diagnosed from presence of IgG antibodies?

A

HSV/Varicella Zoster

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18
Q

Was is meant by laboratory stewardship?

A

Only using lab as a resource when required
-> Most diagnoses are made via history/clinical investigation

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19
Q

What is characteristic about the appearance of herpes viruses?

A

Look like a fried egg

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20
Q

What are the types of herpes virus?

A

Herpes simplex type 1
Herpes simplex type 2
Varicella zoster- chicken pox/shingles
Epstein Barr
Cytomegalovirus
HHV-6
HHV-7
HHV-8 (Kaposi’s Sarcoma Associated virus)

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21
Q

What are the common features of infections with HHVs?

A

Primary infection

Latency

Recurrent infection

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22
Q

What conditions can HSV1/2 cause?

A

Gingivo-stomatitis
Herpes labialis- cold sores
Keratoconjuctivitis
Herpetic whitlow
Bell’s palsy
Genital herpes

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23
Q

What are the steps in the pathogenesis of HSV?

A

Acute infection

Latency

Reactivation

-> Cold sores, viral shedding, cell death

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24
Q

What is the reservoir for HSV?

A

Saliva

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25
Q

What is the route of transmission for HSV?

A

Direct by close person to person contact

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26
Q

When does atypical reactivation of HSV occur? What can be used to diagnose this?

A

In immunocompromised patients

-> take viral swab and do PCR

27
Q

What is used to treat HSV infections?

A

ACV to prevent recurrent infection in difficult cases
(200mg x5 daily ACV)

Topical therapy with ACV (aciclovir cream 5%)

IV therapy for severe & immunosuppressed

28
Q

What is the incubation period for Varicella-zoster?

A

10-21 days

29
Q

What are the potential complications of a Varicella infection?

A

Secondary bacterial infections- group A strep can colonise skin lesions

Pneumonia- vesicles form on epithelial lined surface of lung

Congenital, perinatal/neonatal issues

30
Q

What are the signs and symptoms of zoster infection?

A

Vesicles appear in dermatome of cranial or spinal ganglia where the virus has been dormant

-> The affected area may be intensely painful with associated paraesthesia

31
Q

What are the potential complications of zoster?

A

Post herpetic neuralgia

Secondary bacterial infections

Ophthalmic zoster

Ramsay Hunt syndrome- paralysis of facial nerve

32
Q

What are the stages in the pathogenesis of varicella zoster virus?

A

Primary Infection:
Infection with varicella zoster virus

Latency:
Sensory ganglion (Trigeminal)

Recurrent Infection:
Reactivation of latent virus from sensory ganglion (associated with immunosuppression due to age/tx)

33
Q

What is the route of transmission for Varicella-Zoster?

A

Direct contact, droplet or airborne spread

34
Q

In what groups is occurrence of Varicella and Zoster most common in?

A

V- Children

Z- Immunosuppressed/older

35
Q

What can be used to test for Varicella-Zoster in atypical cases?

A

Swab of vesicular/ulcer fluid in MSM
-> PCR

Serum IgG test (not used for diagnosis of zoster) – usually used for chickenpox exposure in HCW’s

36
Q

How is varicella infection prevented?

A

Chicken pox vaccine (not routine)- only given to patients who are vulnerable to chickenpox/complications

37
Q

How is shingles (zoster) treated?

A

Aciclovir: 800mg Oral x5 daily for 7 days
-> Refer all patients with herpes zoster to a specialist or their general medical practitioner.

38
Q

What is used to prevent zoster infection?

A

Zostavax- Live attenuated virus
-> Schedule: All people aged 70 + years

39
Q

What are the symptoms of an enterovirus infection? (hand, foot and mouth diseases)

A

Fever, runny nose, sneezing, cough, skin rash, mouth blisters, and body/muscle aches

40
Q

What are examples of enteroviruses?

A

Coxsackie- dentally relevant

Polio

41
Q

How does enterovirus infection spread?

A

Nose and throat secretions

Fluid from blisters or scabs

Faeces

42
Q

When are enteroviruses at their most infective?

A

First week

43
Q

Which populations tend to suffer from enterovirus infections?

A

Common in under 5s- nursery/school outbreaks

-> can happen to anyone

44
Q

What can be used to diagnose enterovirus infection?

A

Oral swab for detection of enterovirus RNA
-> not usually required

45
Q

How is hand, foot and mouth disease prevented/treated?

A

P= Hand washing

Tx= Relieve symptoms and treat dehydration

46
Q

What are the signs and symptoms of measles?

A

7-14 days after infection- high fever, runny nose, conjunctivitis, Cough

2-3 days later- Appearance of Koplik spots in the mouth (breakdown of epithelium)

3-5 days later- rash appears on face and spreads downwards

47
Q

What are the potential complications of measles?

A

Pneumonia

Brain swelling

Hearing loss

Diarrhoea

Death

-> MMR vaccine reduces risk

48
Q

How is Measles transmitted?

A

RNA virus is spread through airborne transmission
or direct contact with infected respiratory secretions

49
Q

What is mumps?

A

Epidemic parotitis

50
Q

How long is the incubation period for mumps?

A

12-24 days
-> asymptomatic carriage possible

51
Q

What are the symptoms of mumps?

A

headache
fever
swelling of the parotid glands (uni or bilateral)

52
Q

What other conditions can develop as a result of mumps infection?

A

deafness, encephalitis, pancreatitis, neuritis, arthritis, mastitis, nephritis, thyroiditis, ovaries (oophoritis), swelling of the testes (orchitis) and pericarditis.

53
Q

What type of virus is mumps?

A

Paramyxovirus family - RNA

54
Q

How is mumps spread?

A

Transmission is by direct contact with saliva/fomites or aerosol

55
Q

How is mumps diagnosed?

A

Oral fluid IgM antibody tests or PCR

56
Q

How are measles and mumps prevented?

A

MMR vaccine- routine childhood immunisation

57
Q

What is HPV16 a risk factor for?

A

Head and neck squamous cell carcinoma

58
Q

What is aciclovir?

A

Acyclic purine nucleoside
-> commonly used for intra-oral and perioral viral infection

59
Q

How does aciclovir work?

A

 Tricks replicating herpes virus into incorporating DOG molecule (defective) into growing DNA chain, blocking further synthesis of viral DNA
 Inhibits DNA polymerase (preferential termination- only viral not host DNA)

60
Q

What is aciclovir’s target viral molecule?

A

Viral enzyme- thymidine kinase

-> Higher affinity for acyclovir (only active in infected cells)
-> Mutations in this viral can cause resistance as it avoids action of drug

61
Q

What stage of infection does aciclovir work on?

A

Active replication stage
-> latency phase is not affected

62
Q

What is aciclovir used to treat in a dental setting?

A

Various intra-oral/peri-oral viral infections
-> Herpes simplex (cold sores) and Zoster (shingles) infections

63
Q

How can aciclovir be administered?

A

Topically

Systemically
-> orally or intravenously

64
Q

What is the pro-drug for aciclovir and peniciclovir?

A

A- valacyclovir

P- Famciclovir