Varicella zoster

Question 1

What is varicella zoster?

Answer 1

• Varicella (chickenpox) is caused by the human alpha herpes virus, varicella zoster
• Varicella-Zoster Virus (VZV) → exclusively human virus, incubation period is around 14 days.
• After primary infection, can become latent in dorsal root ganglia and trigeminal ganglia.

Question 2

Describe the epidemiology of varicella zoster

Answer 2

• Over 80% of people have been infected by the age of 10 years
• In around one third of cases, VZV may re-activate later in life to produce shingles

Question 3

What are the risk factors for varicella zoster?

Answer 3

• HIV or immunocompromise (eg. steroid use, chemotherapy) exposure to VZV, age 1-9 years, occupational exposure
• Adults, pregnant women, immunosuppressed patients, and neonates are at high risk of complications from varicella

Question 4

What are the presenting symptoms/ signs of varicella zoster?

Answer 4

• Fever
• Vesicular Rash → first appears centrally, before spreading to extremities
• Vesicles on Mucous Membranes → in nasopharynx
• Pruritus
• Headache, Fatigue/Malaise, Sore Throat
• Shingles ⇒ acute, unilateral, painful blistering rash.

Question 5

What is shingles?

Answer 5

• Acute, unilateral, painful blistering rash.
• Prodromal period with burning pain over affected dermatome for 2-3 days.
• Erythematous, macular rash → vesicular rash.
• Patients are infectious until vesicles have crusted over.
• Tx = paracetamol and NSAIDs.
• Can also give antivirals within 72 hrs.
• Should avoid pregnant women and immunocompromised whilst infectious.

Question 6

What investigations are used to diagnose/ monitor varicella zoster?

Answer 6

1. PCR → positive for virus DNA
2. Ultrasound (Pregnant Women) → screen for fatal consequences of infection

Question 7

How is varicella zoster managed?

Answer 7

1. Supportive Care → paracetamol
2. Risk of moderate-severe disease → oral antiviral therapy (acyclovir)
3. Risk of severe disease → IV antiviral therapy

Question 8

What complications may arise following varicella zoster?

Answer 8

varicella pneumonia, encephalitis, meningitis, hepatitis. Severe infection in the newborn.

1. Ramsay Hunt Syndrome ⇒ LMN facial nerve palsy due reactivation of the varicella zoster virus in the geniculate ganglion of the facial nerve. Auricular pain is first feature, followed by unilateral facial nerve palsy and vesicular rash around the ear (may also get blisters on anterior 2/3 of tongue). Mx with oral aciclovir and corticosteroids (prednisolone).
2. Herpes Zoster Ophthalmicus ⇒ reactivation of the varicella-zoster virus in the area supplied by the ophthalmic division of the trigeminal nerve. Causes vesicular rash around the eye and Hutchinson’s sign (rash on the tip or side of nose). Requires urgent ophthalmology review and oral antivirals for 7-10 days.