Chicken Pox

Question 1

What is Chicken Pox?

Answer 1

• Chickenpox is a highly contagious viral illness
• It causes a classic vesicular rash
• It is caused by Varicella Zoster Virus
• It is a common childhood illness

Question 2

What is Varicella-Zoster Virus?

Answer 2

• It is the cause of both chickenpox and shingles
• The primary VZV infection: this is chickenpox which is characterised by a generalised pruritic vesicular rash seen in children
• Reactivation (shingles): painful unilateral vesicular rash restricted to a dermatomal distribution

Question 3

When is the peak age for Chicken Pox?

Answer 3

• Children less than 10 years old

Question 4

What is the pathophysiology of Varicella-Zoster Virus?

Answer 4

• Following recovery from chickenpox, the virus lies dormant within the dorsal root ganglia
• VZV is a highly contagious virus that is spread by direct contact with vesicle fluid from skin lesions or respiratory droplets
• The incubation period is around 14-16 days
• Patients then develop a generalised papular rash that becomes vesicular
• Patients are considered infective for 48 hours before rash onset until the typical skin lesions have fully crusted over
• Majority of patients make a complete recovery without intervention
• However, the immune system is unable to completely clear the virus which remain dormant within the dorsal root ganglia of nerves

Question 5

What are the Clinical Features of Chicken Pox?

Answer 5

• Generalised Vesicular rash
• Fever intially
• Malaise
• Feeding Problems
• Vomiting/ Diarrhoea
• Headache
• Rash

Question 6

How would you describe the rash?

Answer 6

• The rash starts as a small erythematous macules
• This progresses to papules
• This develops into puritic vesicles
• This then devlops into pustules
• The pustules then burst and begin to crust over from around day 5 after rash onset
• Often left with hypopigmentation of the skin areas after the crusting has fallen off over 1-2 weeks

Question 7

What diagnosis/ Investigations would you consider for Chicken Pox?

Answer 7

• A clinical diagnosis is made for Chickenpox
• A skin swab = PCR

Question 8

What is the managment for Chickenpox?

Answer 8

• Self-limiting, with paracetamol
• Maintain hydration
• Aciclovir (anti-viral therapy), only recommended in adults and older children >14 years old who present with chickenpox within 24 hours of rash onset

Question 9

Who should you ensure your child with chickenpox avoids?

Answer 9

• Infants < 4 weeks old
• Immunocompromised patients
• Pregnant women
• Stay away from school or nursery

Question 10

What is the advice on Chicken pox and pregnancy?

Answer 10

• Chickenpox in pregnancy can be severe
• 10% of women can develop varicella pneumonia
• Pregnant women should avoid patients with chickenpox
• if exposed VZV Antibody status (IgG) should be checked and the Varicella Zoster Immunoglobulin (VZIG) considered if <20 weeks gestation and negative antibodies

Question 11

What is Fetal Varicella Syndrome?

Answer 11

• If pregnant mothers are infected with VZV in the first 28 weeks of pregnancy the fetus is at risk of fetal varicella syndrome
• Characterised by:
• Skin scarring
• Hypoplasia of Limbs
• Neurological disorders (microcephaly (small head), learning difficulties, bladder/bowel dysfunction
• Eye disorder (microphthalmia (small eyes), chorioretinitis, cataracts)

Question 12

What are the complications of Chicken Pox?

Answer 12

• Secondary bacterial infection - NSAIDs increase this risk
• Invasive Group A streptococcal soft tissue infections = Necrotizing fasciitis
• Dehydration
• Pneumonia
• CVS involvement: encephalitis, meningitis, myelitis, Reye’s Syndrome
• Dissmination: pneumonia, hepatitis, encephalitis and DIC
• Haemorrhagic Varricella