top of page

Chickenpox

Chickenpox, also known as Varicella, is caused by the Varicella Zoster Virus (Herpes virus 3 - Herpesvirus Family). It is highly contagious but relatively benign, with humans being the only known natural host. Transmission occurs through respiratory or conjunctival routes via droplets or airborne particles, direct contact with lesions, and rarely through indirect or fomite transmission. Trans placental transmission is also possible. Herpes Zoster, or shingles, is a reactivation of the initial Varicella infection after a latent phase, even from the vaccine virus, though the risk is lower compared to natural infection. The incubation period ranges from 10 to 21 days, averaging 14-15 days, and in infants infected during birth, it ranges from 2 to 16 days, averaging 10-15 days. The disease presents with a generalized, pruritic, vesicular rash with 250 to 500 lesions in varying stages of development. Most vesicles lose the virus after five days. Chickenpox is communicable from 1-2 days before rash onset until 5-6 days after onset or until all vesicles are crusted. Household exposure transmission rates can reach up to 90% in susceptible contacts, with secondary cases often being more severe. The total length of illness is 5-10 days. Breakthrough chickenpox in immunized children tends to be milder with less chance of transmission to others. More severe disease can occur in infants, adolescents, and adults, with first and early second trimester infections potentially leading to fetal death or Varicella embryopathy. Maternal infection 5 days before to 2 days after delivery can result in more severe infection in the baby due to less maternal antibody transfer. Diagnosis is clinical, based on a history of exposure in the previous 10-21 days. Complications can include bacterial superinfection, pneumonia, and CNS issues such as encephalitis and acute cerebellar ataxia. Immunization involves two doses of the live attenuated Varicella vaccine at 15 months and 4-5 years, with effectiveness ranging from 44-88% for complete prevention and 86-90% for prevention of severe disease. Post-exposure vaccination within 3 to 5 days is recommended for those not previously immunized, with two doses if no prior dose was received and a second dose if one dose was received. Treatment is mostly symptomatic, including acetaminophen for fever, oral antihistamines, calamine lotion, daily baths, and measures to prevent scratching for pruritus. Superinfection is treated with topical antibiotics like mupirocin ointment for few lesions or systemic antibiotics like first-generation cephalosporins for more severe infections. Antivirals such as acyclovir are used for Varicella in immunocompetent unvaccinated individuals over 12 years of age, those with chronic lung or skin disorders, those on salicylate therapy, aerosolized or low-dose systemic corticosteroids, and secondary household cases. Hospital admission is required for Varicella pneumonia, moderate to severe immunosuppressed hosts, moderate to severe bacterial complications, and encephalopathy. Rarely, children may get chickenpox a second time, and initial infections in adults can be extremely serious and potentially fatal. The virus can remain inactive in the body's nerve cells for a lifetime, and in 3% to 5% of children, a rash can occur 5 to 26 days after vaccination.

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

bottom of page