Chickenpox

The initial rash, a macular eruption, may be accompanied by an evanescent flush. Within a few hours, lesions progress to papules and then characteristic, sometimes pathognomonic teardrop vesicles, often intensely itchy, on red bases. The lesions become pustular and then crust.

Lesions evolve from macules to papules and vesicles, which then crust. A hallmark of chickenpox is that lesions develop in crops so that they are in various stages of development in any affected region. The eruption may be generalized (in severe cases) involving the trunk, extremities, and face, or more limited but almost always involves the upper trunk.

Ulcerated lesions may develop on the mucous membranes, including the oropharynx and upper respiratory tract, palpebral conjunctiva, and rectal and vaginal mucosa.

In the mouth, vesicles rupture immediately, are indistinguishable from those of herpetic gingivostomatitis, and often cause pain during swallowing.

Scalp lesions may result in tender, enlarged suboccipital and posterior cervical lymph nodes.

New lesions usually cease to appear by the 5th day, and the majority are crusted by the 6th day; most crusts disappear < 20 days after onset.

Sometimes vaccinated children develop varicella (called breakthrough varicella); in these cases, the rash is typically milder, fever is less common, and the illness is shorter; the lesions are contagious.

Secondary bacterial infection (typically streptococcal or staphylococcal) of the vesicles may occur, causing cellulitis or rarely necrotizing fasciitis or streptococcal toxic shock.

Pneumonia may complicate severe chickenpox in adults, neonates, and immunocompromised patients of all ages but usually not in immunocompetent young children.

Myocarditis, hepatitis, and hemorrhagic complications may also occur.

Acute postinfectious cerebellar ataxia is one of the most common neurologic complications; it occurs in 1/4000 cases in children.

Transverse myelitis Acute Transverse Myelitis Acute transverse myelitis is acute inflammation of gray and white matter in one or more adjacent spinal cord segments, usually thoracic. Causes include multiple sclerosis, neuromyelitis optica... read more may also occur.

Reye syndrome Reye Syndrome Reye syndrome is a rare form of acute encephalopathy and fatty infiltration of the liver that occurs almost exclusively in children The cause of Reye syndrome is unknown, but many cases seem... read more , a rare but severe childhood complication, may begin 3 to 8 days after onset of the rash primarily following the use of aspirin.

In adults, encephalitis Encephalitis Encephalitis is inflammation of the parenchyma of the brain, resulting from direct viral invasion or occurring as a postinfectious immunologic complication caused by a hypersensitivity reaction... read more , which can be life threatening, occurs in 1 to 2/1000 cases of chickenpox.

Oral antivirals, when given to immunocompetent patients within 24 hours of the rash’s onset, slightly decrease symptom duration and severity. However, because the disease is generally benign in children, antiviral treatment is not routinely recommended.

Oral valacyclovir, famciclovir, or acyclovir should be given to healthy people at risk of moderate to severe disease, including patients

The dose is famciclovir 500 mg 3 times a day or valacyclovir 1 g 3 times a day for adults. Acyclovir is a less desirable choice because it has poorer oral bioavailability, but it can be given at 20 mg/kg 4 times a day for 5 days for children ≥ 2 years and ≤ 40 kg. The dose for children > 40 kg and adults is 800 mg 4 times a day for 5 days.

Immunocompromised children > 1 year should be given acyclovir10 mg/kg every 8 hours IV. Immunocompromised adults should be treated with acyclovir 10 to 12 mg/kg IV every 8 hours.

Because pregnant women are at high risk of varicella complications, some experts recommend oral acyclovir or possibly valacyclovir for pregnant women with varicella. Although available safety data are reassuring, the safety of antiviral therapy during pregnancy is not firmly established, and there is longer experience with acyclovir in pregnancy compared to valacyclovir. Acyclovir and valacyclovir are pregnancy category B drugs. IV acyclovir is recommended for serious varicella disease in pregnant women. There are little data regarding the safety of famciclovir in pregnancy so it is not generally recommended for pregnant women.

A live-attenuated varicella vaccine Varicella Vaccine Varicella vaccination provides effective protection against varicella (chickenpox). It is not known how long protection against varicella lasts. But, live-virus vaccines, like the varicella... read more is available in 3 formulations in the US:

All healthy children and susceptible adults should receive 2 doses of live-attenuated varicella vaccine (see Centers for Disease Control and Prevention [CDC]: Child and Adolescent Immunization Schedule by Age). Vaccination is particularly important for women of child-bearing age, those at high risk for exposure, and those who have contact with individuals at higher risk for severe disease. These include healthcare professionals, teachers, child care workers, and residents and staff of nursing homes or other institutional settings. Serologic testing to determine immune status before vaccination in adults is usually not required. Rarely the vaccine may cause chickenpox lesions in immunocompetent patients, but disease is usually mild (< 10 papules or vesicles) and brief and causes few systemic symptoms.

Vaccination of health care workers who do not have evidence of varicella immunity is recommended. Susceptible health care workers who have been exposed to varicella should be vaccinated as soon as possible and kept off duty for 21 days.

Vaccination is contraindicated in

After exposure, chickenpox can be prevented or attenuated by intramuscular (IM) administration of varicella-zoster immune globulin (VariZIG). Candidates for postexposure prophylaxis include

The VariZIG immune globulin should be given as soon as possible (and within 10 days of exposure) and may modify or prevent varicella.

Vaccination should be given as soon as possible to exposed, susceptible healthy patients eligible for vaccination (eg, age ≥ 1 year and no contraindications). Vaccination can be effective in preventing or ameliorating disease within 3 days and possibly up to 5 days after exposure.

To prevent nosocomial transmission, the Centers for Disease Control and Prevention recommends postexposure prophylaxis with vaccination or varicella-zoster immunoglobulin, depending on immune status, for exposed health care workers and patients without evidence of immunity (available at Immunization of Health-Care Personnel).