Varicella infection (incomplete)

What is antiviral therapy for varicella?

For patients ≥2 years with normal renal function, we administer oral acyclovir or valacyclovir. If antiviral therapy is initiated (eg, immunocompetent patients at increased risk of developing complications from varicella), treatment should be started within 24 hours after the rash develops, if possible.

What is the impact of vaccination on the clinical presentation of varicella?

Approximately 20 percent of children who receive one dose of varicella vaccine may develop varicella infection, known as "breakthrough disease", if exposed to VZV.

How is varicella transmitted?

Chickenpox is highly contagious, with secondary household attack rates of >90 percent in susceptible individuals. Transmission occurs in susceptible hosts via contact with aerosolized droplets from nasopharyngeal secretions of an infected individual or by direct cutaneous contact with vesicle fluid from skin lesions.

What are contraindications to varicella vaccination?

Contraindications to administration of varicella vaccine include: ●Severe allergic reaction (eg, anaphylaxis) to a previous dose of varicella vaccine or component of varicella vaccine (eg, neomycin, gelatin); varicella vaccines do not contain egg protein. ●Pregnancy or trying to become pregnant; immunization before and after pregnancy is discussed separately. ●Severe immunosuppression. ●Untreated active tuberculosis.

What is immunization for varicella?

In children, the first dose of varicella vaccine is usually administered at age 12 through 15 months and the second dose at age 4 through 6 years. We suggest separate varicella and MMR vaccines for children 12 through 47 months of age (ie, administered at the same visit, but at different sites). We suggest MMRV for children 48 months through 12 years of age. The dose of varicella vaccine (single-antigen or MMRV) is 0.5 mL. Varicella-containing vaccines are administered subcutaneously, usually in the upper outer triceps.

What are risk factors for varicella infection?

Ninety percent of children who died did not have identifiable risk factors for severe varicella. The most frequent varicella-related complications in children were secondary bacterial infections and pneumonia.

How does varicella affect children differently than adults?

Primary infection with VZV routinely occurs during childhood and is usually a benign self-limited illness in immunocompetent children. However, varicella can be a severe disease in adolescents, adults, and immunosuppressed or immunocompromised individuals of any age. Secondary cases in household contacts appear to be more severe than primary cases.

What is Reye syndrome?

Reye syndrome, an illness developing during the course of varicella infection in children, typically presents with a distinct constellation of symptoms including nausea, vomiting, headache, excitability, delirium, and combativeness with frequent progression to coma. Since salicylate use was identified as a major precipitating factor for the development of Reye syndrome, this complication has virtually disappeared, concomitant with advisories against using salicylates in febrile children.

What are complications of varicella infection?

Skin/soft tissue infections — Primary varicella infection in children has been associated with an increased incidence of invasive group A streptococcal soft tissue infection. Infectious complications have included cellulitis, myositis, necrotizing fasciitis, and toxic shock syndrome. Neurologic complications — Encephalitis and, mostly in the past, Reye syndrome, are the most serious complications of VZV infection, although they are uncommonly seen. Pneumonia — In immunocompetent children with varicella, pneumonia remains an uncommon complication; in contrast, pneumonia accounts for the majority of morbidity and mortality seen in adults with varicella.

How does uncomplicated varicella present clinically?

The clinical manifestations of varicella in healthy children generally develop within fifteen days after the exposure and typically include a prodrome of fever, malaise, or pharyngitis, loss of appetite, followed by the development of a generalized vesicular rash, usually within 24 hours. The vesicular rash of varicella, which is usually pruritic, appears in successive crops over several days. The lesions begin as macules that rapidly become papules followed by characteristic vesicles; these lesions can then develop a pustular component followed by the formation of crusted papules. The patient with varicella typically has lesions in different stages of development on the face, trunk and extremities. New vesicle formation generally stops within four days, and most lesions have fully crusted by day six in normal hosts. Crusts tend to fall off within about one to two weeks and leave a temporary area of hypopigmentation in the skin.

What is the epidemiology of varicella?

The epidemiology of varicella outbreaks (defined as ≥5 varicella cases epidemiologically linked to a common setting that occurred within one incubation period) have significantly decreased in number, size, and duration with the introduction of varicella vaccine.

What is the appropriate supportive care for varicella?

The following general measures can be used for the symptomatic management of rash and fever, and can also help reduce the risk of developing certain complications: ●Antihistamines are helpful for the symptomatic treatment of pruritus. ●Fingernails should be closely cropped to avoid significant excoriation and secondary bacterial infection. ●Acetaminophen should be used to treat fever, particularly in children. Salicylates should be avoided since aspirin has been associated with the onset of Reye syndrome in the setting of a viral infection

What is the incidence of varicella?

Varicella occurs throughout the year in temperate regions, but the incidence typically peaks in the months of March through May. According to national seroprevalence data from the pre-vaccine era, greater than 95 percent of persons in the United States acquired varicella before 20 years of age, and fewer than 2 percent of adults were susceptible to infection

What is varicella?

Varicella-zoster virus (VZV) infection causes two clinically distinct forms of disease: varicella (chickenpox) and herpes zoster (shingles). Primary VZV infection results in the diffuse vesicular rash of varicella, or chickenpox.

When is antiviral therapy indicated for varicella infection?

We suggest oral antiviral therapy for immunocompetent children and adolescents who are at increased risk of developing complications from varicella (eg, pneumonia, skin infection), since antiviral therapy may theoretically reduce the risk of complications in these patients and is generally well tolerated. These individuals include: ●Unvaccinated adolescents (ie, children ≥13 years of age) since these patients are more likely to have severe disease compared with younger children. ●Secondary cases in household contacts since these cases are usually more severe than primary cases. ●Patients with a history of chronic cutaneous or pulmonary disorders since secondary bacterial infections may have severe consequences. ●Children taking intermittent oral or inhaled steroid therapy. The risk is greatest when corticosteroids are administered during the incubation period. ●Individuals taking chronic salicylates. These individuals are at risk of developing Reye syndrome. We suggest not administering antiviral therapy for healthy children ≤12 years.