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DEN303 - IHD > Human Herpesviruses > Flashcards

Human Herpesviruses Flashcards

Structure and classification of Herpesviruses What disease are caused by Herpesviruses How Herpesviruses infect human cells Pathobiology of Herpes simplex virus and other Herpesviruses

1
Q

Herpeton

A
  • greek for creep
    Icosahedral capsid surrounding ds DNA
    Virus size 120-200 nm
    80 genes coding for 100 proteins
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2
Q

beta herpes

slow growth in t cells and leukocytes

A

cytomegalovirus
human herpesvirus 6
human herpesvirus 7

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3
Q

gamma herpes virus

A

epstein barr

human herpesvirus 8

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4
Q

herpes simplex virus 1+2

A

oropharyngeal and genital herpes

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5
Q

varicella zoster

A

chicken pox / shingles

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6
Q

epstein barr virus

A

infectious mononucleosis, burkitt’s lymphoma, nasopharyngeal carcinoma

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7
Q

cytomegalovirus

A

Cytomegalic inclusion disease in utero (newborns and immunocompromised)

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8
Q

HHV 6

A

Exanthem Subitum (6th disease)?
HHV-7 HHV-8
Fatigue syndrome

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9
Q

HHV 7

A

Pityriasis rosea?

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10
Q

HHV 8

A

Kaposi’s Sarcoma (in AIDS patients)

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11
Q

Infection and replication

A

Hijacks host cell machinery
Viral cell injects DNA into host cell and gets uncoated
Transcription of DNA
Translation of viral proteins
Factor produced with has high affinity for host cell DNA polymerase - alters specificity
Viral DNA replicated and reinserted into viruses –> mature viruses
Viruses break out of nuclei and cytosis occurs

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12
Q

HSV1

Process
Symptoms

Reactivation

A

Mainly oral infections
- herpetic gingivostomatitis

  • virus enters trigeminal sensory neurones and affect sensation and motor fx
  • migrates to trigeminal ganglion
  • 50% becomes reactivated and migrates to peripheral nerve endings
  • causes 2ndary pathology
  • shedding of viruses at epithelial level
  • herpes labialis - cold sores
  • XS UV light
  • stress
  • illness
  • immuno suppression

Lesion resolves
Virus lays dormant again in trigeminal ganglion until reactivated

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13
Q

HSV 2

Cause

A

Mainly genital infections

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14
Q

Natural history of HSV infections

source of virus -

symptoms

A

Primary infection
Skin lesions
Saliva

genital lesions
genital secretions
90-99% asymptomatic
1-10% symptomatic

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15
Q

primary HSV

A

Very common

Mainly affects young children and young adults

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16
Q

primary HSV

A

Very common

Mainly affects young children and young adults

17
Q

Herpetic gingivostomatitis
Clinical features

diagnosis

investigation

A 
Incubation period 3-10 days
Duration 5-14 days 
multiple vesicles rupture to form sloughing ulcers
gingivitis with erythema and sloughing 
malaise, pyrexia and lymphadenopathy 
Diagnosis:
Typical clinical appearance
Main diagnostic difficulty with erythema
multiforme
Investigation:
Not normally done
Rising antibody titre / presence of IgM antibodies
Viral culture or now mainly PCR
18
Q

Management of primary HSV

A

Acyclovir (200mg 5 x daily for 5 days) if found early or in immunocompromised
Fluids and soft diet
Analgesics / antipyretics (paracetamol)
Local antiseptics e.g. chlorhexidine Topical analgesics e.g. Difflam X-infection control

19
Q

Clinical features of 2ndary HSV

Management

Prophylaxis

A

Prodromal irritation
vesicles at or near mucocutaneous junction of lips
Crusting lesions 7-10 days
Usually reoccurs at the same sites

May occur intra-orally in nose or elsewhere

Acyclovir cream 5% if used OTC drying and antibacterial agentsvery early
Prophylactic:

rarely justified
prevents lesions in immunocompromised or those susceptible to erythema multiforme

20
Q

Value of Acyclovir in Herpes Labialis

A

Prophylactic - oral ACV (600-1000mg/day in 2 doses) is effective.
Reduces duration of pain by 1.4 days
Reduces time to lesion crusting by 2.1 days
Reduces occurrence of new lesions by at least
50%
Increases mean time to next recurrence from 46
to 118 days
Reduces mean number of recurrences over a 4 - month observation period

21
Q

Herpetic whitlow

Features

A

Herpetic infection of the fingers from handling the oral tissues of someone with active 1° or 2° Herpes simplex lesions (mainly dentists)
Very painful
Very difficult to treat Prevention better than cure - wear gloves

22
Q

HSV encephalitis

adults

neonates

A

70-80% mortality if untreated
only people >50s (HSV1) and neonates (HSV2) affected

Adults (HSV-1)
•Headache and behavioural changes over several days •Fever
•only 11% of cases have a history of recurrent HSV infections

Neonates (HSV-2)
•Skin rash, lesions and CNS symptoms
•Virus present in liver, lung and adrenal glands
•Respiratory distress
•Fits and convulsions
•Raised intracranial pressure
•Incidence is approximately one case per 300,000 live births in the UK

23
Q

HSV 2

A

Mainly genital

multiple vesicles rupture to form extensive sloughing ulcers

24
Q

HHV 3

1mary infection

reactivation

2ndary infection

A

varicella zoster
many similarities in structure and infection to HSV 1 and 2

chicken pox - varicella
- dominant in dorsal root/trigeminal ganglia

  • age >50
  • stress
  • illness
  • immunosuppression

herpes zoster - shingles

25
Q

Chicken pox - varicella

A

2ndary viraemia takes 10 days post infection

26
Q

Herpes zoster

oral disease

3 phases

A

2ndary infection
most commonly affects chest and back
fluid filled rashes

most commonly affects one division of the trigeminal N

pre-herpetic neuralgia
rash
post herpetic neuralgia

27
Q

pre herpetic neuralgia

A

Pain in the distribution of the affected
division of the trigeminal nerve
Prior to the development of the rash May mimic dental pain

28
Q

rash (PHN)

A 
Unilateral vesicles in the
distribution of a branch of the
trigeminal nerve   Ophthalmic
  Maxillary
  Mandibular
Vesicles break down to form
  Ulcers (mucosa)
  Crusting lesions (skin)
Last 2-3 weeks
29
Q

Problems with zoster affecting ophthalmic region –

A

> glaucoma, cataract, double vision and corneal scarring

30
Q

Herpes zoster management

new alternatives

A

Acyclovir 800mg 5 x daily for 7 days if seen soon after lesions develop
Analgesics
Ophthalmic referral if eye involved
Avoid contact with children

Valaciclovir 1g 3 x daily for 7 days Famciclovir 250mg 3 x daily for 7 days

31
Q

Post-herpetic neuralgia

A

10% of patients go on to get extremely unpleasant intractable burning pain in the distribution of the affected nerve
More common in the elderly
Effective early treatment of zoster may ↓ risk of neuralgia
Treat pain with tricyclic anti-depressants and neuropathic pain drugs

32
Q

Epstein Barr virus

Associated with

Named after Anthony Epstein & Yvone Barr who discovered the virus in 1964

A

HHV4

Infectious Mononucleosis (Galndular Fever) – acute 1o infection with EBV
Burkitt’s Lymphoma – a B-cell malignancy
Nasopharyngeal Carcinoma – an epithelial cell malignancy
Oral Hairy Leukoplakia – seen in AIDS patients and some transplant recipients

33
Q

Epstein Barr mechanism

Why is latent infection needed?

A

Primary infection EBV replicates in ora-pharyngeal epithelial cells
Becomes latent in B cells

Virus persistence, subsequent replication in epithelial cells and release of infectious virus into saliva

34
Q

Infectious mononucleosis

Oral manifestation

A

About 95% of the world’s population are infected with EBV
Most infections are asymptomatic
Symptoms include sore throat, swollen cervical lymph nodes and mild fever
Infections in the western world are usually seen in young adults
The disease can run a prolonged, episodic course, interfering with physical and scholastic performance (good excuse for poor exam results )

Petechiae on soft palate
Creamy exudates on fauces Cervical lymphadenopathy

35
Q

Burkitt’s lymphoma

Prevalence

Manifests

Treatment

A

Malignant B cell lymphoma

High prevalence in children in tropical africa <1500m where malaria is present
Affects children sub clinically

Usually affects jaw bone as tumour mass
Nasopharyngeal carcinoma

Severe, clinical EBV infections early in childhood predispose to Burkitt’s Lymphoma – EBV immortalises B cells
Treatment – cyclophosphamide (chemo

36
Q

HHV 5

Rarely causes

Immunocompromised/AIDS

A

Cytomegalovirus

Glandular fever like illness
Salivary gland swelling

Large ragged oral mucosal ulcers
Salivary gland swelling
Retinitis

37
Q

HSV 8 in AIDS

A

Kaposi’s sarcoma

DEN303 - IHD (58 decks)

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