Chickenpox

Question 1

Chickenpox Pathogen

Answer 1

• Varicella zoster

- Reactivation leads to herpes zoster (shingles)

Question 2

Chickenpox Infectivity

Answer 2

• A few days from onset of lesion until crusts fall off

- Can catch chickenpox from shingles but not the other way round (still rare)

Question 3

Chickenpox Presentation

Answer 3

• Infection and immunity can occur without disease
• Virus enters through URT
• First feature is pyrexia
• Headache, malaise, abdominal apin
• Crops of vesicles appear over 3-5 days, mostly on head, neck, trunk
• Very itchy, papule, vesicle, pustule to crust
• Pneumonia common in immunocompromised

Question 4

Chickenpox Differentials

Answer 4

• Usually clear diagnosis
• Generalised herpes zoster or simplex
• Dermatitis herpetiformis
• Impetigo
• Guttate psoriasis

Question 5

Chickenpox Investigations

Answer 5

• Usually clinical

- Confirmation can be obtained by taking scraping

Question 6

Chickenpox Management

Answer 6

• Minimise scratching
• First 1-2 days are most infectious
• Symptomatic treatment
• Sedating antihistamines

Question 7

Chickenpox Aciclovir Indications

Answer 7

IV

• High risk patients, strongly immunosuppressed (e.g. HIV CD4<200, organ transplant)
• Systemic disease
• Patients on high dose steroids
• New lesion after 8 days

Oral

• Chronic medical condition
• Secondary case
• Pregnant patients

Question 8

Chickenpox Contacts Management

Answer 8

• If face-to-face for longer than 4 hours and 5-7 days after exposure, if high risk (incl. no PHx, give oral aciclovir)
• If high risk and under 96 hours after exposure, give VZIG

Question 9

Chickenpox Complications

Answer 9

• Secondary infections of lesions can occur, usually from scratching
• Viral pneumonia
• Encaphalitis