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Renal and Genito-Urinary System > Human Herpes Virus > Flashcards

Human Herpes Virus Flashcards

1
Q

What is the size of the Herpes Virus?

A

120-200nm

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2
Q

What disease does Herpes simplex virus 1 & 2 cause?

A

Oropharyngeal & Genital Herpes

(HSV 1 - mainly oral infections
HSV 2 - mainly genital infections)

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3
Q

What disease does Varicella-Zoster Virus (HHV-3) cause?

A

Chicken pox (Varicella) / Shingles (Zoster)

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4
Q

How does HSV-1 cause oral infections?

A

Herpetic gingivostomatitis

  • The virus enters trigeminal sensory neurones
  • Migrates to trigeminal ganglion
  • In 50% of cases it remains dormant in the trigeminal ganglion
  • In 50% of cases it becomes reactivated and migrates to peripheral nerve endings were active viral particles are shed.
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5
Q

How is the HSV reactivated?

A

Reactivation of Herpes Simples Infection (Herpes Labialis - cold sores)

  • UV light
  • Stress
  • Illness
  • Immuno-suppression

The lesion resolves. The virus lays dormant again in trigeminal ganglion until reactivated

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6
Q

Which group of people does herpetic gingivostomatitis (HSV-1) mostly affect?

A

Mainly affects young children (usually mild, may go unnoticed)

Sometimes young adults (often more severe)

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7
Q

What are the clinical features of Herpetic Gingivostomatitis (HSV-1)

A
  • Incubation period 3-10 days
  • Duration 5-14 days
  • Multiple Vesicles - rupture to form extensive sloughing ulcers
  • Gingivitis with erythema and sloughing
  • Malaise, pyrexia, lymphadenopathy
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8
Q

How are we able to investigate Herpetic Gingivostomatitis (HSV-1)

A
  • Rising antibody titre
  • Presence of IgM antibodies
  • Viral culture (now mainly PCR)
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9
Q

What is the Basic method of PCR

A
  1. ) DENATURE DNA to single stands
  2. ) ANNEALING PRIMERS of specific primers to DNA
  3. ) EXTENSION BY POLYMERASE
  4. ) AMPLIFICATION - Repeat 30-35 times
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10
Q

How do we manage Herpetic Gingivostomatitis (HSV-1)

A
  • Acyclovir (200mg 5 x daily for 5 days) if found early or in immunocompromised
  • Fluids and soft diet
  • Analgesics/Antipyretics
  • Local antiseptics e.g. chlorhexidine
  • Topical analgesics e.g. Difflam
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11
Q

Action of Acyclovir

A
  • HSV thymidine kinase phosphorylates guanosine (G) when HSV DNA replicates
  • Human cells cannot phosphorylate ACV very well
  • In HSV-infected cells, ACV is phosphorylated by the viral TK enzyme to ACV-P
  • ACV-P then inhibits virus replication
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12
Q

What are the clinical features Herpes Labialis (Reinfection 2 HSV) - Cold Sores

A
  • Prodromal irritation
  • Vesicles at or near mucocutaneous junction of lips
  • Crusting lesions lasting 7-10 days
  • usually reoccur at same sites
  • Rarely:
    may occur, intra-orally, in nose or elsewhere on skin
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13
Q

Management of Herpes Labialis

A
  • Acyclovir cream 5% if used very early
  • OTC drying and antibacterial agents

PROPHYLACTIC TMT:
]• Rarely justified
• Prophylactic acyclovir will prevent lesions in the immunocompromised or those susceptible to erythema multiforme

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14
Q

Value of Acyclovir in Herpes Labialis

A
  • Reduces duration of pain by 1.4 days
  • Reduces occurrence of new lesions by at least 50%

Reduces time to lesion crusting by 2.1 days

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15
Q

What are the features Herpetic Whitlow

A

• Herpetic infection of the fingers from handling the oral tissues of someone with active 1 or 2 HS lesions

  • Very painful
  • Very difficult to treat
  • Prevention better than cure (wear gloves)
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16
Q

What is HSV Encephalitis

A
  • Mainly affects frontal lobes of the brain
  • 70-80% mortality if untreated
  • Only 3% of survivors return to normal

Usually only people >50 years (HSV-1) and neonates (HSV-2) affected

17
Q

Feature of HSV Encephalitis

A

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 cranial pressure
  • 1 in 300,000 births in UK
18
Q

What is HHV-3

A

HHV-3 = Varicella-Zoster Virus

  • Primary Infection - Chicken pox (Varicella)
  • Secondary Infection - Herpes zoster (Shingles) - Chest and Back most common

(secondary infection being reactivated by Age, Stress, Illness, Immunosuppression)

19
Q

What are the Three phases of infection with Herpes Zoster (2nd infection)

A
  1. ) Pre-herpetic neuralgia
  2. ) Rash
  3. ) Post-herpetic neuralgia
20
Q

What are the clinical features of 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
21
Q

Clinical features of the rash in Herpes Zoster infection

A
  • Unilateral vesicles in the distribution of a branch of the trigeminal nerve
  • These vesicles break down to form:
  • Ulcers (mucosa)
  • Crusting lesions (skin)
  • Lasts 2-3 weeks
  • In the eye:
  • Glaucoma
  • Cataract
  • Double vision
  • Scarring of the cornea
22
Q

How do we manage Herpes Zoster Infection?

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

New alternatives to acyclovir:

  • Valaciclovir 1g 3 x daily for 7 days
  • Famciclovir 250mg 3 x daily for 7 days
23
Q

Describe 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 decrease risk of neuralgia
  • Treat pain with tricyclic anti-depressants and neuropathic pain drugs
24
Q

What are the associated diseases with HHV-4 - Epstein-Barr Virus (EBV)

A
  • Infectious Mononucleosis (Glandular fever) - Acute Primary 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.
25
Q

What is the infection course of the EBV?

A
  • Primary infection EBV replicates in oro-pharyngeal epithelial cells but then establishes latency in B-lymphocytes
  • EBV latent infection of B-lymphocytes is necessary for virus persistence, subsequent replication in epithelial cells and release of infectious virus into saliva.
26
Q

What is Infectious Mononucleosis (EBV)?

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 usually seen in young adults
  • The disease can run a prolonged, episodic course, interfering with physical and scholastic performance
27
Q

Clinical features of infectious mononucleosis

A
  • Petechiae on soft palate
  • Creamy exudates on fauces
  • Cervical lymphadenopathy
28
Q

What is Burkitt’s Lymphoma?

A
  • A malignant, B-cell lymphoma of high prevalence in children in tropical Africa at elevations below 1500 meters where malaria is present
  • Severe, clinical EBV infections early in childhood predispose to Burkitt’s Lymphoma - EBV immortalises B cells
  • Treatment - cyclophosphamide (chemo)
  • Usually presents as a tumour mass in the jaw bone
29
Q

What are the clinical features of HHV-5 Cytomegalovirus (CMV)

A

In healthy individuals rarely causes:

  • Glandular fever-like illness
  • Saliva gland swelling

In immunocompromised/AIDS can cause:

  • Large ragged oral mucosal ulcers
  • Salivary gland swelling
  • Retinitis
30
Q

What can HSV-8 cause?

A

• In aids patients can cause:

- Kaposi’s sarcoma

Renal and Genito-Urinary System (3 decks)

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