Chickenpox

Chickenpox (Varicella)

• Varicella Zoster Virus (Herpes virus 3 - Herpesvirus Family)

• Highly contagious but relatively benign - Humans only known natural host

• Transmission:

  • Respiratory or conjunctival route - droplet or airborne; Direct Contact with lesion (Indirect or Fomite transmission rare)

  • Trans placental transmission

• Herpes Zoster: Reactivation of initial Varicella infection after latent phase (even vaccine virus can cause Herpes Zoster after latency - but risk is low compared to natural infection)

• Incubation period: 10-21 days (Avg 14-15days); in infants infected during birth 2-16days (Avg 10-15 days)

• Generalized, Pruritic, Vesicular rash - 250 to 500 lesions - in varying stages of development

• Most vesicles loose virus after 5 days

• Communicability: 1-2 days before rash onset until 5 -6 days after onset or until all vesicles crusted

• Household exposure transmission rate up to 90% in susceptible contact - secondary cases more severe

• Total Length of illness 5-10 days

• Breakthrough Chickenpox in immunized children: milder illness - less chances of transmission to other contacts

• More severe disease

  • Infants, adolescents and adult

  • First and early second trimester infection - Fetal death or Varicella embryopathy

  • Maternal infection 5 days before up to 2 days after Delivery (more severe infection to baby (less maternal antibody transfer))

• Diagnosis Clinical (H/O exposure in previous 10-21 days)

• Complications: Bacterial superinfection, Pneumonia, CNS(encephalitis, Ac Cerebellar ataxia),

• Immunization: Vaccine: 2 doses at 15mo and 4-5yrs (Live attenuated Varicella Vaccine)

  • Effectiveness (44-88% complete prevention and 86-90% prevention of severe disease)

  • Exposure to chickenpox: Vaccine within 3 to 5 days of being exposed (If not immunized previously - 2doses; If one dose received give second dose)

• Treatment (Mostly Symptomatic)

  • Fever

  • : Acetaminophen (Paracetamol)

  • Pruritus

  • : Oral Antihistamines, Calamine Lotion, Daily Baths, Cut Nails, can use Gloves or Socks

  • Superinfection

  • (usually group A streptococci or Staph aureus): Few Lesion- Topical antibiotics like Mupirocin ointment; More severe infection - systemic antibiotics like first generation cephalosporins (Cephalexin, Cefadroxil) or other antibiotics

  • Antivirals

  • :

  • Acyclovir:

  • 
    

    • Varicella: Oral: 10 days (80mg/kg/day into 4 dev doses up to adult dose of 800 mg 4 times daily)

    • Zoster:>12yr: Oral: 5-7 days (4000 mg /day into 5 dev doses)

    • Not routinely advised for <12yr age

    • Indicated in immunocompetent

      • Unvaccinated people above >12yr of age, Chronic Lung Disease, Chronic Skin Disorder, Those on Salicylate therapy, Aerosolized or low dose systemic corticosteroids, Secondary Household cases

• Admission : Varicella Pneumonia; Mod to severe Immunosuppressed host; Mod to severe bacterial complications ; Encephalopathy

• Comments:-

  • Rarely, children get chickenpox a second time

  • Initial chickenpox infections in adults can be extremely serious and may result in death.

  • The chickenpox virus can stay for a lifetime in an inactive form in the body’s nerve cells.

  • In 3% to 5% of children rash can occur 5 to 26 days after varicella vaccination