Varicella zoster

Question 1

Define

Answer 1

DEFINITION: primary infection is called varicella (chickenpox). Reactivation of the dormant virus (found in dorsal root ganglia), causes zoster (shingles).

NOTE: varicella zoster is also known as herpes zoster

Question 2

Causes

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

Symptoms

Answer 4

Chickenpox

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

Shingles

Shingles

• May occur after a period of stress
• 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
• Painful skin lesions
• Recovery: 10-14 days

Question 5

Signs

Answer 5

Chickenpox

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

Shingles

• Vesicular maculopapular rash
• Dermatomal distribution
• Skin excoriation

Question 6

Investigations

Answer 6

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 7

Management

Answer 7

Chickenpox

• Children - treat symptoms
• Adults - consider aciclovir

Shingles

• Aciclovir, valaciclovir, famciclovir

Prevention

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

Question 8

Complications

Answer 8

Chickenpox

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

Shingles

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

• Sacral zoster
• Motor zoster

Question 9

Prognosis

Answer 9

Depends on complications

Worse in pregnancy, elderly and immunocompromised