Varicella Zoster

Question 1

Define varicella zoster

Answer 1

Primary infection with varicella zoster virus causes chickenpox
Reactivation of the dormant virus in the dorsal root ganglia causes shingles (herpes zoster)

Question 2

What are the causes/risk factors of varicella zoster?

Answer 2

• VZV is part of the human herpesvirus family (HHV-3) and is a dsDNA virus
• Transmitted by aerosol inhalation or direct contact with vesicular lesions
• Incubation period ~14 days
• Highly contagious – patient is infectious before onset of rash and remains infectious
until all the lesions have crusted over
- High risk of severe disease if pregnant, neonate, immunocompromised
• Increased risk of reactivation -> shingles if:
- Immunocompromised – HIV, corticosteroids, chemotherapy

Question 3

What are the symptoms of varicella zoster?

Answer 3

Chickenpox
• Malaise
• Sore throat
• Headache
• Intensely itchy rash – face and trunk >
extremities, oropharynx, conjunctivae, GU tract

Shingles
• Tingling
• Hyperaesthesia
• Painful skin lesions

Question 4

What are the signs of varicella zoster?

Answer 4

Chickenpox
• Mild pyrexia
• Maculopapular rash -> weeping vesicles
(exudate) and crusting
• Skin excoriation

Shingles
• Vesicular maculopapular rash in
dermatomal distribution
• Skin excoriations

Question 5

What investigations are carried out for varicella zoster?

Answer 5

• Often a clinical diagnosis (both chickenpox and shingles).
• In high-risk patients, adults, or other patients in whom the diagnosis is unclear, laboratory testing can confirm the diagnosis.
- PCR off skin lesion.
- Viral culture
- DFA: Direct fluorescent antibody testing. Positive for VZV antigen (indicating that virus is present).

Question 6

What is the management for varicella zoster?

Answer 6

Chickenpox
Children: 
• Paracetamol analgesia 
• Anti-histamines e.g. diphenhydramine 
• Emollients e.g. calamine lotion

Adults or Moderate Risk of Severe Disease:
• Anti-viral therapy (oral) e.g. acyclovir
• Paracetamol analgesia
• Anti-histamines e.g. diphenhydramine
• Emollients e.g. calamine lotion.

Patients with or at High Risk of Severe Disease:
• Anti-viral therapy (IV) e.g. acyclovir
• Paracetamol analgesia
• Anti-histamines e.g. diphenhydramine
• Emollients e.g. calamine lotion

Shingles:
• Oral antiviral e.g. acyclovir.
• Low-dose amitriptyline may benefit those with moderate/severe discomfort.
• Simple analgesia (paracetamol)

Question 7

What are the complications of varicella zoster?

Answer 7

Chickenpox:  
• Secondary infection 
• Scarring 
• Pneumonia 
• Encephalitis 
• Cerebellar syndrome 
• Congenital varicella syndrome: scarring, ophthalmic defects, limb dysplasia and CNS abnormalities. Occurs in 1–2% of offspring of mothers who developed chickenpox <20 weeks gestation. 

Shingles:
• Postherpetic neuralgia
• Zoster opthalmicus (rash involves V1).
• Ramsay Hunt syndrome: The reactivation of virus in 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 may lead to urinary retention.
• Motor zoster (muscle weakness of myotome at similar level as involved dermatome)