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Flashcards in Human Herpes Virus Deck (30)
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1

What is the size of the Herpes Virus?

120-200nm

2

What disease does Herpes simplex virus 1 & 2 cause?

Oropharyngeal & Genital Herpes

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

3

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

Chicken pox (Varicella) / Shingles (Zoster)

4

How does HSV-1 cause oral infections?

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.

5

How is the HSV reactivated?

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

6

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

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

Sometimes young adults (often more severe)

7

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

- 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

8

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

- Rising antibody titre
- Presence of IgM antibodies
- Viral culture (now mainly PCR)

9

What is the Basic method of PCR

1.) DENATURE DNA to single stands

2.) ANNEALING PRIMERS of specific primers to DNA

3.) EXTENSION BY POLYMERASE

4.) AMPLIFICATION - Repeat 30-35 times

10

How do we manage Herpetic Gingivostomatitis (HSV-1)

- 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

11

Action of Acyclovir

- 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

12

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

- 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

13

Management of Herpes Labialis

• 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

14

Value of Acyclovir in Herpes Labialis

• 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

15

What are the features Herpetic Whitlow

• 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)

16

What is HSV Encephalitis

• 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

Feature of HSV Encephalitis

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

What is HHV-3

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

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

1.) Pre-herpetic neuralgia

2.) Rash

3.) Post-herpetic neuralgia

20

What are the clinical features of Pre-herpetic neuralgia:

• Pain in the distribution of the affected division of the trigeminal nerve

• Prior to the development of the rash

• May mimic dental pain

21

Clinical features of the rash in Herpes Zoster infection

• 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

How do we manage Herpes Zoster Infection?

• 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

Describe Post-herpetic neuralgia

• 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

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

• 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

What is the infection course of the EBV?

• 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

What is Infectious Mononucleosis (EBV)?

• 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

Clinical features of infectious mononucleosis

• Petechiae on soft palate

• Creamy exudates on fauces

• Cervical lymphadenopathy

28

What is Burkitt's Lymphoma?

• 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

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

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

What can HSV-8 cause?

• In aids patients can cause:
- Kaposi's sarcoma