Varicella (Chickenpox): The Highly Contagious Childhood Rash Explained

Varicella, commonly known as chickenpox, is a highly contagious viral infection caused by the varicella-zoster virus (VZV), a member of the herpesvirus family. It was once considered a near-universal childhood illness before the introduction of effective vaccines. The disease is characterized by an intensely itchy rash that develops into fluid-filled blisters before crusting over and healing. While chickenpox is usually mild in healthy children, it can cause serious complications in infants, adults, pregnant women, and immunocompromised individuals.

Chickenpox typically begins with one to two days of fever, fatigue, headache, and loss of appetite before the characteristic rash appears. The rash starts as small red spots that quickly develop into raised bumps, then fluid-filled vesicles that look like tiny blisters. Over the next several days, these blisters break open, ooze, and form crusty scabs as they heal. A distinctive feature of chickenpox is that lesions in different stages appear simultaneously on the body, so you can see spots, blisters, and scabs all at the same time.

Varicella is one of the most contagious diseases known, spreading easily through respiratory droplets when an infected person coughs, sneezes, or talks. Direct contact with the fluid from chickenpox blisters is another route of transmission. An infected person is contagious from about one to two days before the rash appears until all the blisters have crusted over. In household settings, the transmission rate to susceptible family members is estimated at 80 to 90 percent.!!

For most healthy children, chickenpox treatment focuses on relieving symptoms and preventing complications. Calamine lotion, oatmeal baths, and oral antihistamines can help manage the intense itching. aspirin should never be given to children with chickenpox due to the risk of Reye syndrome.!! For adolescents, adults, and those at high risk, antiviral medications such as acyclovir or valacyclovir can reduce the severity and duration when started within 24 hours of the rash appearing.

While chickenpox is typically mild in healthy children, complications can be serious and sometimes life-threatening. Bacterial skin infections from scratching the blisters are the most common complication, potentially leading to cellulitis or scarring. More severe complications include pneumonia, encephalitis, and bloodstream infections.

Pregnant women who contract chickenpox face risks to both themselves and their unborn child. Immunocompromised individuals are at particular risk for widespread, severe disease.

The varicella vaccine, introduced in the mid-1990s, has dramatically reduced the incidence and severity of chickenpox worldwide. The standard vaccination schedule involves two doses, the first at 12 to 15 months of age and the second at 4 to 6 years of age. Vaccination is approximately 90 percent effective at preventing chickenpox entirely and nearly 100 percent effective at preventing severe disease. Even individuals who develop breakthrough chickenpox after vaccination typically experience a much milder illness.

After a person recovers from chickenpox, the varicella-zoster virus does not leave the body but instead becomes dormant in nerve cells near the spinal cord and brain. Years or decades later, the virus can reactivate and cause herpes zoster, commonly known as shingles, which produces a painful blistering rash along a single nerve dermatome. The risk of shingles increases with age and with any condition that weakens the immune system. A shingles vaccine is now recommended for adults over 50.

When dealing with a rash that could be chickenpox, having a way to visually document and analyze the lesions can be extremely helpful. Skinscanner allows you to photograph skin changes and receive AI-powered analysis that can help distinguish between different types of rashes and vesicular conditions. Tracking the progression of lesions through their various stages provides useful information that you can share with your healthcare provider. While chickenpox should always be evaluated by a medical professional, Skinscanner serves as a valuable tool for initial assessment and ongoing monitoring.