Herpes Simplex Virus

Question 1

List the herpesvirus classification.

Answer 1

Question 2

Define herpes simplex virus.

Answer 2

Disease resulting from HSV1 or HSV2 infection.

Question 3

What kind of viruses are HSV1 and 2?

Answer 3

Large, enveloped, double-stranded DNA viruses.

Question 4

What is HSV1 AKA and what does it cause?

Answer 4

Cold sores

• Herpes labialis - lips
• Herpetic whitlow - painful infection on fingers

Question 5

How common is HSV1?

Answer 5

Very common

90% of adults seropositive for HSV1 by age 30yrs (can be asymptomatic)

Question 6

How is HSV1 spread?

Answer 6

Respiratory droplets

Saliva

Question 7

How does HSV1 present?

Answer 7

• Gingivostomatitis, cold sores (herpes labialis)
• Herpetic whitlow
• Eczema herpeticum
• Herpes simplex meningitis, encephalitis
• Systemic infection
• Keratoconjunctivitis

Question 8

What is HSV2 AKA and what does it cause?

Answer 8

Genital herpes

Question 9

How does HSV2 present?

Answer 9

• Genital herpes (chronic-life long)
• flu-like prodrome
• vesicles/papules around genitals, anus
• shallow ulcers
• urethral discharge
• dysuria
• fever and malaise

Question 10

How is HSV2 spread?

Answer 10

• Sexual contact
• Perinatal

Question 11

What is the aetiology of HSV1 and 2?

Answer 11

• Virus becomes dormant following primary infection - trigeminal/sacral root ganglia
• Reactivation may occur in response to stress or immunosuppression

Question 12

What are the two phases of HSV?

Answer 12

Has a latent and lytic phase:

Latent phase - chronic infection where infectious virons are not produced –> asymptomatic

Lytic phase - viral replication and transport of virus to skin and mucosal surfaces–> active infection

Question 13

Describe the pathophysiology of herpes simplex virus.

Answer 13

• Acquired at mucosal surfaces or breaks in the skin
• Virus replicates in epidermis then infects sensory or autonomic nerve ending and travels via retrograde axonal transport to sensory ganglia.
• It then enters latent phase, evading the immune system to cause lifelong infection
• Periodic reactivation of the virus produces lytic replication when the virus travels by anterograde transport doen axons to the mucosal or cutaneous surface.
• Reactivation may lead to asymptomatic shedding of virus –> neuropathic tingling and burning to recurrent ulceration
• Timing and source is often diffucult to determine because virus is asymptomatic in when acquired
• HSV is associated with CD4+ and CD8+ T cells and antibodies.

Question 14

What investigations would you do fos HSV infection?

Answer 14

Usually clinical diagnosis

May consider viral culture* and HSV PCR**, glycoprotein G based type specific serology.

• *Viral culture - highest yield if vesicles can be unroofed and the base of an ulcer can be scraped with a Dacron swab
• **HSV PCR - as above; higher sensitivity than viral culture

Question 15

How do you manage HSV infection?

Answer 15

• oral aciclovir, valaciclovir or famciclovir *
• symptomatic treatment - paracetamol, lidocaine 5% topical,
• topical antiviral - docosanol topical 10%

*IV if there is disseminated visceral involvement (pneumonitis, hepatitis or SN involvement)