Varicella Zoster

Question 1

Definition

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/Risk factors

Answer 2

· VZV is a herpes ds-DNA virus

· Highly contagious

· Transmission by aerosol inhalation or direct contact with vesicular secretions

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

Presenting symptoms (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

Presenting symptoms (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 on physical examination (chickenpox)

Answer 6

o Maculopapular rash

o Areas of weeping and crusting

o Skin excoriation (from scratching)

o Mild pyrexia

Question 7

Signs on physical examination (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 plan

Answer 9

· Chickenpox
o Children - treat symptoms
o Adults - consider aciclovir

· Shingles
o Aciclovir, valaciclovir, famciclovir

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

Question 10

Possible complications (chickenpox)

Answer 10

o Secondary infection
o Scarring
o Pneumonia
o Encephalitis
o Congenital varicella syndrome

Question 11

Possible complications (shingles)

Answer 11

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 12

Prognosis

Answer 12

· Depends on complications

· Worse in pregnancy, elderly and immunocompromised