Chicken pox

• Chickenpox is a highly contagious disease caused by the varicella-zoster virus (VZV).
• It can cause an itchy, blister-like rash.
• The rash first appears on the chest, back, and face, and then spreads over the entire body, causing between 250 and 500 itchy blisters. Chickenpox can be serious, especially in babies, adolescents, adults, pregnant women, and people with a weakened immune system. The best way to prevent chickenpox is to get the chickenpox vaccine.

Chicken Pox (Varicella Zoster)

History

• In the United States in the early 1990s, an average of 4 million people got chickenpox, 10,500 to 13,000 were hospitalized, and 100 to 150 died each year.
• Chickenpox vaccine became available in the United States in 1995.
• Each year, more than 3.5 million cases of chickenpox, 9,000 hospitalizations, and 100 deaths are prevented by chickenpox vaccination in the United States.

Signs and Symptoms

• Anyone who has not had chickenpox or gotten the chickenpox vaccine can get the disease.
• Chickenpox illness usually lasts about 4 to 7 days.
• The classic symptom of chickenpox is a rash that turns into itchy, fluid-filled blisters that eventually turn into scabs.
• The rash may first show up on the chest, back, and face, and then spread over the entire body, including inside the mouth, eyelids, or genital area.
• It usually takes about one week for all of the blisters to become scabs.

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Chicken pox

Other typical symptoms that may begin to appear 1-2 days before rash include:

• fever
• tiredness
• loss of appetite
• headache

Incubation Period and Prodrome

• The average incubation period for varicella is 14 to 16 days after exposure to a varicella or a herpes zoster rash, with a range of 10 to 21 days.
• A mild prodrome of fever and malaise may occur 1 to 2 days before rash onset, particularly in adults. In children, the rash is often the first sign of disease.

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CHicken Pox Blisters

Varicella in Unvaccinated Persons

• The rash is generalized and pruritic.
• It progresses rapidly from macular to papular to vesicular lesions before crusting.
• Lesions are typically present in all stages of development at the same time.
• The rash usually appears first on the chest, back, and face, then spreads over the entire body.
• The lesions are usually most concentrated on the chest and back. Symptoms typically last 4 to 7 days.

Breakthrough varicella

• Breakthrough varicella is infection with wild-type varicella-zoster virus (VZV) occurring in a vaccinated person more than 42 days after varicella vaccination.
• Breakthrough varicella is usually mild.
• Patients typically are afebrile or have low fever and develop fewer than 50 skin lesions.
• They usually have a shorter illness compared to unvaccinated people who get varicella.

Transmission

• Varicella is highly contagious.
• The virus can be spread from person to person by direct contact, inhalation of aerosols from vesicular fluid of skin lesions of acute varicella or zoster, and possibly through infected respiratory secretions that also may be aerosolized.
• A person with varicella is contagious beginning 1 to 2 days before rash onset until all the chickenpox lesions have crusted.
• Vaccinated people may develop lesions that do not crust.
• These people are considered contagious until no new lesions have appeared for 24 hours.
• It takes from 10 to 21 days after exposure to the virus for someone to develop varicella.

Did you know that varicella is less contagious than measles, but more contagious than mumps and rubella?.

Chicken pox scabs day 4

Acyclovir Treatment

The American Academy of Pediatrics (AAP) recommends that certain groups at increased risk for moderate to severe varicella be considered for oral acyclovir or valacyclovir treatment. These high risk groups include:

• Healthy people older than 12 years of age
• People with chronic cutaneous or pulmonary disorders
• People receiving long-term salicylate therapy
• People receiving short, intermittent, or aerosolized courses of corticosteroids

Best time for antivirals

• Some healthcare providers may elect to use oral acyclovir or valacyclovir for secondary cases within a household. For maximum benefit, oral acyclovir or valacyclovir therapy should be given within the first 24 hours after the varicella rash starts.
• Oral acyclovir or valacyclovir therapy is not recommended by AAP for use in otherwise healthy children experiencing typical varicella without complications.

Intravenous acyclovir therapy is recommended for severe disease (e.g., disseminated VZV such as pneumonia, encephalitis, thrombocytopenia, severe hepatitis) and for varicella in immunocompromised patients (including patients being treated with high-dose corticosteroid therapy for >14 days).

Famciclovir is available for treatment of VZV infections in adults, but its efficacy and safety have not been established for children. In cases of infections caused by acyclovir-resistant VZV strains, which usually occur in immunocompromised people, Foscarnet should be used to treat the VZV infection, but consultation with an infectious disease specialist is recommended.

Assessing Immunity to Varicella

Two doses of varicella vaccine are recommended for all children, adolescents, and adults without evidence of immunity to varicella. Those who previously received one dose of varicella vaccine should receive their second dose for best protection against the disease.

Complications

Complications from chickenpox can occur, but they are not common in healthy people who get the disease. People who may get a serious case of chickenpox and may be at high risk for complications include:

• Infants
• Adolescents
• Adults
• Pregnant women
• People with weakened immune systems because of illness or medications, for example,
• People with HIV/AIDS or cancer
• Patients who have had transplants, and
• People on chemotherapy, immunosuppressive medications, or long-term use of steroids.

Serious complications

Serious complications from chickenpox include:

• Bacterial infections of the skin and soft tissues in children, including Group A streptococcal infections
• Infection of the lungs (pneumonia)
• Infection or inflammation of the brain (encephalitis, cerebellar ataxia)
• Bleeding problems (hemorrhagic complications)
• Bloodstream infections (sepsis)
• Dehydration

Death is rare.

Prevention

• The best way to prevent chickenpox is to get the chickenpox vaccine.
• Everyone – including children, adolescents, and adults – should get two doses of chickenpox vaccine if they have never had chickenpox or were never vaccinated.
• Chickenpox vaccine is very safe and effective at preventing the disease.
• Most people who get the vaccine will not get chickenpox.
• If a vaccinated person does get chickenpox, the symptoms are usually milder with fewer or no blisters (they may have just red spots) and mild or no fever.
• The chickenpox vaccine prevents almost all cases of severe illness.
• Since the varicella vaccination program began in the United States, there has been over 90% decrease in chickenpox cases, hospitalizations, and deaths.

Chicken pox Resources
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