Episode Details

Varicella (chickenpox) is an acute infectious disease caused by the varicella-zoster virus (VZV), a DNA virus in the herpesvirus group,. Following primary infection, the virus persists as a latent infection in sensory nerve ganglia and can reactivate later in life as herpes zoster (shingles),.

• Transmission: The virus is highly contagious and spreads person-to-person via air (coughing/sneezing) or direct contact with vesicular fluid. It is communicable from 1–2 days before the rash appears until all lesions have crusted,.

• Incubation: Symptoms typically develop 10 to 21 days after exposure,.

• Symptoms: The hallmark symptom is an itchy rash that progresses rapidly from flat red spots (macules) to fluid-filled blisters (vesicles) and finally to scabs,. Lesions appear in successive "crops," meaning different stages of the rash are present simultaneously.

Clinical Severity and Complications

While often mild in healthy children, varicella can be severe or life-threatening in adults, pregnant women, and immunocompromised individuals,.

• Complications: Common complications include secondary bacterial skin infections (Staphylococcus or Streptococcus) and pneumonia. Central nervous system issues, such as encephalitis and cerebellar ataxia, are rare but serious.

• Reye Syndrome: Aspirin or salicylate-containing products must never be given to children with chickenpox, as this significantly increases the risk of Reye syndrome, a serious condition affecting the liver and brain,.

• Pregnancy: Maternal infection in the first 20 weeks of gestation can result in congenital varicella syndrome (limb hypoplasia, scarring, microcephaly).

Vaccination and Immunity

Since the introduction of the vaccine in 1995, varicella incidence in the U.S. has declined by an average of 97%.

• Vaccine Types: Two live, attenuated vaccines are licensed: VAR (Varivax) and the combination MMRV (ProQuad).

• Schedule: A 2-dose series is recommended for children: the first dose at 12–15 months and the second at 4–6 years. Adolescents and adults without immunity should also receive two doses, spaced at least 4 weeks apart.

• Efficacy: Two doses are 92% effective against any clinical varicella and 98% effective against severe disease.

• Breakthrough Infection: Infection can occur in vaccinated individuals but is typically milder, often with fewer than 50 lesions and no fever.

• Contraindications: Live vaccines should not be administered to pregnant women, individuals with severe allergic reactions to vaccine components (gelatin/neomycin), or those with severe immunosuppression (e.g., certain HIV counts, leukemia),.

Post-Exposure and Management

• Prophylaxis: Vaccination is 70% to 100% effective in preventing or modifying illness if administered within 3 to 5 days of exposure.

• Treatment: Routine care involves fluids, acetaminophen for fever, and anti-itch lotions. Antiviral medicines are reserved for those at high risk of complications, such as adults and immunocompromised patients