Varicella (Chickenpox)

Varicella, or chickenpox, is a vaccine preventable virus caused by varicella zoster and is one of the classic childhood diseases, occurring in children under the age of ten. It is also one of the most contagious. Chickenpox consists of hundreds of itchy, fluid-filled blisters throughout the surface of the body. The blisters eventually burst and can scar the skin. Sometimes complications may arise, such as skin infections or pneumonia, causing hospitalization. In the United States, there are less than 4 million cases of chickenpox annually with approximately 4,000 to 9,000 cases that have serious complications, causing about 100 deaths. These deaths usually occur in individuals with weak immune systems, newborns, and adults. Chickenpox cases are more severe in adults and, although it is rare for adults to get the chickenpox, they account for over half the deaths. In adults, the varicella virus can also cause shingles, which is the re-emerging of chickenpox after many years.

Since many people are now vaccinated for varicella, the number of cases has been decreasing, but chickenpox has not been eliminated. Chickenpox is highly contagious and can be spread very easily by direct contact and droplet/airborne transmission, such as coughing or sneezing. The period of contagiousness begins approximately 1 to 2 days before onset of rash and ends when all lesions have crusted over. Once contracted, the symptoms begin to appear in about two weeks, but an individual may be symptom free for up to 21 days.

Symptoms that occur a few days before the pox outbreak include:

• Fever
• Headache
• Stomach ache
• Loss of appetite

The average child develops 250 to 500 small, blistery red spots on the skin, usually on the face, trunk, or scalp and spread from there. In a few days, the original red spots will scab over as new spots arise. Most pox will not leave scars unless they become infected from scratching. If vaccinated, it is still possible to develop a mild case of chickenpox, but recovery time and the number of pox are reduced.

Once a person has had chickenpox, the virus usually remains in the body for a lifetime, but is repressed by the immune system. If the immune system becomes weak or there is a period of high stress, the chickenpox can re-emerge as shingles in about 1 in 10 adults.

It is hard to prevent the contraction of the chickenpox because individuals are contagious and can spread the virus before any symptoms or blisters appear. The best preventative measure that can be taken is to be vaccinated. The vaccine is routinely recommended for children over 12 months of age and other susceptible individuals. People over 13 years of age should receive 2 doses of vaccine, separated by at least 4 weeks.

The risk of transmission of vaccine virus from a vaccinated person to a susceptible contact appears to be very low. Transmission of vaccine virus appears to occur primarily if and when the vaccinee develops a vaccine-associated rash, which could occur up to 42 days after vaccination.

Approximately 1 percent of vaccinees per year have developed breakthrough infections, i.e., developed varicella disease even though they had responded to the vaccine. Breakthrough infection is significantly milder with fewer lesions (generally fewer than 50), many of which are maculopapular rather than vesicular. Most persons with breakthrough infection do not have fever. Varicella transmission from vaccine recipients with mild breakthrough disease has been documented but is rare.

Please contact your doctor, local health department or the Department of Health and Senior Services (866-628-9891) if you have other questions about varicella.