What is Chickenpox

© 2009 Nucleus Medical Media, Inc.

Chickenpox is a highly contagious viral infection. It produces a widespread itchy rash and crusting. Chickenpox is caused by the varicella zoster virus (VZV). The virus can spread from person to person via:

• Airborne droplets of moisture containing the VZV virus
• Direct contact with fluid from a chickenpox rash

The virus is most contagious for 1-2 days before the rash erupts and during the first day or so after the rash has broken out. It remains contagious until all of the blisters have crusted.

Because of an extensive vaccination program, the incidence of chickenpox has declined greatly in the United States. The majority of cases (about 90%) occur in infants, children, and adolescents under age 14. The incidence among adults 20 or older is very low (approximately 5% of cases). When contracted during childhood, chickenpox is usually not serious. Serious complications are more common when contracted by adults (including adolescents), newborns, or people with a suppressed immune system. These complications can include:

• Pneumonia (usually in adults or older children)
• Liver or kidney inflammation
• Central nervous system complications, including:
  • Asceptic meningitis
  • Acute cerebellar ataxia (most common)
  • Encephalitis
  • Transverse myelitis
  • Guillain-Barré Syndrome
  • Reye's Syndrome (generally only in children and teenagers)
• Bacterial infections from Group A streptococci and Staphylococcus aureus leading to infections in the skin (Cellulitis), Toxic Shock Syndrome, bacteremia, arteritis, Gangrene , Osteomyelitis, and Pericarditis.
• Bleeding problems due to low platelet counts
• If a susceptible mother catches chickenpox while pregnant, damage to the baby may occasionally result. Some associated birth defects include: poor growth of arms or legs, skin scarring, small head, and perhaps mental retardation or other abnormalities of the nervous system
• Shingles is a complication of chickenpox that can occur years later.