Varicella Zoster

Question 1

Define:

Answer 1

• Primary infection is called varicella (chickenpox). Reactivation of the dormant virus (found in dorsal root ganglia), causes zoster (shingles).
o NOTE: varicella zoster is also known as herpes zoster

Question 2

Aetiology:

Answer 2

• VZV is a herpes ds-DNA virus
• Highly contagious
• Transmission by aerosol inhalation or direct contact with vesicular secretions
• Incubation period is 11-21 days and initial varicella infection is a contagious febrile illness with crops of blister at various stages
• After infection, virus is dormant in doral root ganglia
• Reactivation causes shingles – pain and rash in dermatomal distribution precedes malaise and fever by some days

Question 3

Epidemiology:

Answer 3

Chicken pox peak incidence: 4-10 yrs
• Shingles peak incidence: > 50 yrs
• 90% of adults are VZV IgG positive

Question 4

Symptoms of chicken pox:

Answer 4

o Prodromal malaise
o Mild pyrexia
o Sudden appearance of intensely itchy spreading rash mainly affecting face and trunk
o Vesicles weep and crust over
o New vesicles appear
o Contagious from 48 hrs before the rash until after the vesicles have all crusted over (7-10 days)

Question 5

Symptoms of Shingles:

Answer 5

o May occur after a period of stress
o Tingling/hyperaesthesia in a dermatomal distribution
• Dermatomal because the rash remains dormant in the dorsal root ganglia and reactivation makes the virus travel down the sensory axon to produce a dermatomal shingles rash
o Painful skin lesions
o Recovery: 10-14 days

Question 6

Signs of chicken pox:

Answer 6

o Maculopapular rash
o Areas of weeping and crusting
o Skin excoriation (from scratching)
o Mild pyrexia

Question 7

Signs of shingles:

Answer 7

o Vesicular maculopapular rash
o Dermatomal distribution
o Skin excoriation

Question 8

Investigations:

Answer 8

• Usually CLINICAL diagnoses
• Vesicle fluid may be sent for electron microscopy viral PCR (RARELY necessary)
• Chicken pox in an adult with previous history of varicella infection may require HIV testing

Question 9

Management of chicken pox:

Answer 9

o Children - treat symptoms

o Adults - consider aciclovir

Question 10

Management of shingles:

Answer 10

o Aciclovir, valaciclovir, famciclovir
o If conjunctiva affected, use 3% acyclovir ointment
o Post herpetic neuralgia in affected dermatomes can last years – it is hard to treat and can be intolerable. Can try amitriptyline, topical lidocaine patches or gabapentin +/- carbamazepine. Last resort: ganglion ablation

Question 11

Prevention of shingles:

Answer 11

Varicella Zoster Ig (VZIG) - may be considered in immunosuppressed or pregnant

Question 12

Complications of chicken pox:

Answer 12

o	Secondary infection 
o	Scarring 
o	Pneumonitis and ataxia
o	Purpura fulminans 
o	DIX 
o	Pneumonia 
o	Encephalitis 
o	Congenital varicella syndrome

Question 13

Complications of shingles:

Answer 13

o Postherpetic neuralgia
o Zoster ophthalmicus (rash in the ophthalmic division of the trigeminal nerve)

o Ramsay-Hunt syndrome

• DEFINITION: reactivation of VZV in the geniculate ganglion causing zoster of the ear and facial nerve palsy. Vesicles may be seen behind the pinna of the ear or in the ear canal
o Sacral zoster
o Motor zoster

Question 14

Prognosis:

Answer 14

• Depends on complications

* Worse in pregnancy, elderly and immunocompromised