Chickenpox

Essentials

• An effective vaccine against chickenpox containing live attenuated viruses is available http://www.cdc.gov/chickenpox/vaccination.html http://www.ecdc.europa.eu/en/publications-data/public-health-guidance-varicella-vaccination-european-union. Find out about its inclusion in the local national immunization programme. See also Vaccinations Vaccinations.
• Chickenpox in an otherwise healthy child below 12 years of age does not usually require treatment with an antiviral drug.
• Prevent chickenpox in immunocompromized patients with Zoster hyperimmunoglobulin and treat symptomatic disease with antiviral drugs.
• Chickenpox can also be highly severe in patients who are on glucocorticoid medication, severely atopic or HIV positive, or who have received stem cell transplantation, as well as in patients over 12 years of age: consider antiviral medication in these patient groups.
• Recurring fever and/or intensive pain in the recovery phase suggest a bacterial complication and indicate hospital treatment.

Clinical picture

• There are usually no prodromal symptoms.
• A maculopapular rash starts suddenly and quickly develops into vesicles (pictures ). Lesions at different stages are simultaneously found on the skin (pictures ). The vesicles are mainly found on the trunk, and they may also occur on the scalp and also in the mucous membranes, e.g. in the mouth.
• The patient often is febrile in the initial phase of the rash.
• Pneumonia (cough, opacity in chest x-ray) is rare in children but occurs in 15-30% of adults. The risk is increased during pregnancy and in smokers.

Complications

• Streptococci and staphylococci can cause secondary bacterial infections. If a patient with chickenpox develops anew a high fever and has severe pains, remember the possibility of complications, e.g. necrotizing fasciitis Severe Infections of the Skin and Soft Tissues, caused by invasive streptococci.
• 10% of all cases of Reye's syndrome are associated with chickenpox. Therefore, aspirin must not be given to patients with chickenpox.
• Meningoencephalitis is rare but severe complication (1:3000-10 000).
• Post-infectious cerebellitis presents as cerebellar symptoms (ataxia, disturbance of balance) after chickenpox infection. It resolves spontaneously.

Contagiousness

• Chickenpox is easily spread by droplets already about 1-2 days before the emergence of the rash. Infectivity continues until all the vesicles have become crusted (for at least about 5 days form the emergence of the rash).
• The incubation period is 10-21 days: shorter in immunocompromised patients and longer after administration of Zoster hyperimmunoglobulin (ZIG).

Diagnosis

• Chickenpox is usually easily recognizable and no laboratory investigations are required.
• In patients belonging to risk groups, the diagnosis can be confirmed from a sample taken with a cotton swab from the bottom of a vesicle for PCR testing. A PCR test from the cerebrospinal fluid or synovial fluid is also possible.

Treatment Acyclovir for Treating Varicella in Otherwise Healthy Children and Adolescents

• If an immunocompromized individual gets chickenpox he/she should receive acyclovir in a hospital.
  • Factors that predispose to severe chickenpox include primary immunodeficiencies that particularly affect the amount or function of T cells, cytotoxic medication that is going on or has been terminated less than 3 months earlier, high-dose glucocorticoid treatment that has lasted for more than 14 days, some other immunosuppressive treatment, HIV infection, and sequelae of stem cell transplantation.
  • Varicella-zoster virus is less susceptible to acyclovir than Herpes simplex virus. Hence acyclovir treatment is usually started intravenously (1 500 mg/m² /24 hours divided into 3 doses). The dosage is reduced in renal insufficiency. In mild cases, oral valacyclovir therapy may be sufficient.
• Treatment of a child that has otherwise been healthy with acyclovir is usually not necessary. Treatment is clearly indicated if the child has severe atopy or if he/she is more than 12 years old. The dose for adults is 800 mg 4 times daily for 5 days and for children 20 mg/kg 4 times daily for 5 days, orally. The treatment effect is the best if the medication is started within 24 hours of onset of the rash.
• Itch can be treated with hydroxyzine (1-2 mg/kg/day in several divided doses) taking into account, however, its sedative effect. Secondary bacterial infections of the skin (intensive, painful erythema of the skin around crusts, impetigo) can be treated, for example, with cephalexin (50 mg/kg/day perorally). The surroundings of healing crusts are always somewhat erythematous.
• The healed crusts may leave scars on the skin (picture ).
• If there is a suspicion of invasive streptococcal complication, refer the patient emergently to a hospital where intravenous antimicrobial treatment with a combination of penicillin and clindamycin is started and, if necessary, the infection focus is surgically incised Severe Infections of the Skin and Soft Tissues.

Prevention Vaccines for Post-Exposure Prophylaxis Against Varicella (Chickenpox) in Children and Adults

• Zoster hyperimmunoglobulin (ZIG) should be given to a patient evidently exposed to chickenpox who has leukaemia, lymphoma, or congenital or acquired immunodeficiency, and who has not had chickenpox before or the history is unclear.
  • Exposure is defined as a case of chickenpox or herpes zoster in the family, or chickenpox in a companion (with whom the patient has been in skin contact or has spent time indoors face-to-face for more than 5 minutes or has been in the same room for more than 15 minutes). In a hospital, exposure is defined as a case in the same room. If the brother or sister of a child has been exposed to chickenpox, he/she may be infectious after 8 days from the exposure at the earliest.
  • ZIG (125 IU/10 kg i.m., maximum dose 625 IU) should be given within 72 hours of exposure. However, there is no absolute limit in this regard. If the patient is repeatedly exposed in less than 2 weeks from the previous dose of immunoglobulin, only half a dose is administered.
• In addition to ZIG, prophylactic acyclovir may be started in risk situations (dosage: 40 mg/kg/24 hours divided into 4 doses, max. 800 mg × 4, for 5 days) 7-9 days after the exposure, whereupon the onset of the disease is prevented or the disease appears only in a mild form. In patients with severe immunodeficiency, a therapeutic dose may also be used.
• Also varicella vaccine given within 3 days from the exposure significantly reduces the onset of a symptomatic disease.

Varicella vaccine Live Attenuated Varicella Vaccine for Healthy Children, Vaccines for Post-Exposure Prophylaxis Against Varicella (Chickenpox) in Children and Adults

• The effect of the vaccine containing live attenuated virus http://www.dynamed.com/condition/chickenpox#VARICELLA_VIRUS_VACCINE_LIVE is best in healthy children. About 5% of them have a mild exanthema after the vaccination. In children with cancer the vaccine fails more often and adverse effects are more common. Most effective protection of children belonging to risk groups is achieved by vaccinating other children.
• The vaccination is given in two doses http://www.cdc.gov/chickenpox/vaccination.html. Find out about local practice concerning timing of the doses.
  • In Finland, for example, this is done at the age of 1.5 years and at the age of 6.
  • See also the article Vaccinations Vaccinations.
• It is recommended that all persons who are over 12 years of age and have not had chickenpox should be vaccinated using two doses of vaccine at a 3-month interval. Prior testing for antibodies is not needed.

Chickenbox in pregnant women and at the time of delivery

• If a woman gets chickenpox 0-5 days before delivery or during the first two days after delivery there is a high risk of infection of the foetus or neonate. About 17% of such neonates are clinically infected, with a mortality as high as 31%. Therefore all exposed neonates should be treated with ZIG and prophylactic acyclovir. If the neonate becomes symptomatic, acyclovir is administered intravenously at a therapeutic dose.
• If one of the neonate's sisters or brothers gets chickenpox the neonate need not be treated with ZIG.
• Chickenpox may be dangerous for a pregnant woman. Chickenpox in a pregnant woman or chickenpox exposure in a pregnant woman who has not had the disease is an indication for immediate consultation with a gynaecologist or specialist in internal medicine. Decisions on treatment are made in the hospital individually.

Herpes zoster

• Varicella-zoster virus (VZV) remaining latent in the body may, when reactivated, cause herpes zoster (shingles) in the area of 1-3 sensory dermatomes.
• Also children may get herpes zoster, especially if they had chickenpox in a mild form during the first year of life.
• Covering the lesion is sufficient for isolation.

Pictures