Chicken Pox

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Chicken pox and shingles are caused by the same virus (Varicella or Herpes Zoster). Humans are the only source of infection for chicken pox and shingles. Person-to-person transmission occurs by direct contact with vesicular fluid from patients with either condition. Chicken pox may additionally be transmitted by airborne spread from  respiratory tract secretions. There is a risk of infection up to 21 days after contact.  

Chicken pox is a highly contagious viral illness usually occurring in epidemics. It is generally a benign, self-limiting  disease in immuno-competent children but tends to be more severe in adolescents and adults and also in immunosuppressed patients e.g. patients on steroids. Complications include bacterial super-infection of skin lesions, pneumonia, central nervous system involvement (acute cerebellar ataxia, encephalitis), thrombocytopenia, and other rare complications such as glomerulonephritis, arthritis, and hepatitis. 

Exposure to the virus during the second 20 weeks of pregnancy can result in congenital varicella syndrome characterised by skin scarring, abnormalities of limbs, brain, eyes and low birth weight. Varicella infection can be fatal for an infant if the mother develops varicella from 5 days before to 2 days after delivery.

Shingles presents with skin lesions in a dermatomal distribution and in immunocompromised individuals, can be very extensive. It may be complicated by pain persisting for weeks to years after the infection (postherpetic neuralgia). 

Cause

• Varicella-Zoster (or Herpes Zoster) virus

Symptoms

Chicken pox

• Fever
• Malaise
• Anorexia
• Headache 
• Itchy skin rash

Shingles

• Painful rash
• Fever

Signs

Chickenpox

• Vesicular rash eventually becoming crusted
  • Rash in different stages (papules, vesicles, crusted lesions)
  • Appear first on face, scalp or trunk and spreads to rest of body, more concentrated on trunk
  • Persists for 5-7 days
  • Presence of pus in lesions suggests secondary bacterial infection

Shingles

• Vesicular rash
  • Along a dermatome 
  • Rash eventually crusts

Investigations

• Usually none (diagnosis is mainly clinical)
• Polymerase Chain Reaction (PCR) or cell culture from vesicular fluid, crusts, saliva, cerebrospinal fluid or other specimens (if diagnosis in doubt)

TreatmentTreatment Objectives

• To relieve the intense itching or pain  
• To prevent or treat secondary infection
• To prevent dehydration in children 

Non-pharmacological treatment

• Avoid scratching  
• Regular bathing with soap and water 
• Avoid intentionally breaking up vesicles

Pharmacological treatment 

See sections below

Referral CriteriaRefer when severe complications set in. Also refer patients who are at risk of developing a disseminated rash e.g. patients on steroid therapy, other immunocompromised states and the newborn whose mother has had a recent infection.