Varicella (Chicken Pox)
Varicella (Chicken Pox)
An acute, highly contagious, viral disease caused by Varicella Zoster Virus. It spreads by infective droplets or fluid from vesicles. One attack confers permanent immunity.
Varicella is contagious from about 5 days before the onset of the rash until the crusts begin to disappear.
Reactivation of the virus may appear later as zoster or shingles. Incubation period is 2–3 weeks. Patients are most contagious from 1–2 days before onset of the rash until crusting of lesions.
Complications are more common in immunocompromised patients and include: Secondary skin infection, pneumonia, necrotising fasciitis, encephalitis, haemorrhagic varicella lesions with evidence of disseminated intravascular coagulation.
Two important bacteria causing complications are S.aureus and S. pyogenes.
Diagnoses
Mild headache, fever and malaise
Characteristic rash: lesions progress from macules to vesicles in 24–48 hours,successive crops appear every few days.
Vesicles, each on an erythematous base, are superficial, tense ‘teardrops’ filled with clear fluid which dry to form fine crusts.
The rash is more profuse on the trunk and sparse at the periphery of extremities at the height of eruption, all stages (macules, vesicles and crusts) are present at the same time the rash lasts 8–10 days and heals without scarring, unless secondarily infected mucous membranes may be involved pruritus may be severe.
Management
- Isolate the patient
- Neonate: Isolate from mother until the mother is regarded as non-contagious
- Maintain adequate hydration
Antiviral therapy
For immunocompetent patients with varicella complications and for all immunocompromised patients. Initiate as early as possible, preferably within 24 hours of the appearance of the rash.
- Aciclovir oral 20 mg/kg 8 hourly daily for 5 days (Max: 800 mg/dose) OR
- Aciclovir IV 10mg/kg/dose 8 hourly administered over 1 hour for 7–10 days
Pruritus: Calamine lotion, topical, applied 3 times daily
Promethazine oral 0.25–0.5 mg/kg/dose 6 hourly for 24–48 hours
Secondary skin infection: Cephalexin oral 7.5 mg/kg/dose 6 hourly for 5 days
Prophylaxis
- Neonates whose mothers develop varicella from 5 days before delivery to 2 days after delivery: Varicella-zoster immunoglobulin IM (VAZIGAM ®)1 mL(100 units) given within 96 hours of exposure. If varicella-zoster immunoglobulin is not available treat with Aciclovir 20 mg/kg/dose 8 hourly for 10 days.
- If baby develops varicella treat with Aciclovir 20 mg/kg/dose IV 8 hrly. (Gestational age <35 weeks give same dose 12 hrly)
- Immunocompromised children exposed to varicella:
- Aciclovir oral, 20 mg/kg/dose 8 hourly for 10 days