Shingles and Chickenpox (Varicella-Zoster Virus)

Description

Alternative Names

Risk Factors

The varicella-zoster virus is responsible for both chickenpox and herpes zoster, but its method of infection is different in both diseases.

• Both the active varicella and zoster form of the virus can cause chickenpox.
• The shingles virus in its latent (inactive) form is never infectious.

Catching Chickenpox. Most people get chickenpox from exposure to other people with chickenpox. It is most often spread through sneezing, coughing, and breathing. It is so contagious that few nonimmunized people escape this common disease when they are exposed to someone else with the disease.

People can also catch chickenpox from direct exposure to a shingles rash if they have not been immunized by vaccination or a previous bout of chickenpox. In such cases, transmission happens during the active phase when blisters have erupted but have not formed dry crusts. Herpes zoster spreads only from the rash. A person with shingles cannot transmit the virus by breathing or coughing.

Developing Shingles. Shingles itself can only develop from a reactivation of the varicella-zoster virus in a person who has previously had chickenpox. In other words, shingles itself is never transmitted from one person to another either in the air or through direct exposure to the blisters.

Risk Factors for Chickenpox (Varicella)

Between 75% and 90% of chickenpox cases occur in children under 10 years of age. Before the introduction of the vaccine, about four million cases of chickenpox were reported in the US each year. Since a varicella vaccine became available in the US in 1995, however, the incidence of disease and hospitalizations due to chickenpox are showing a dramatic decrease of over 80% in some states. Experts expect the disease to become a rarity in the US.

The disease usually occurs in late winter and early spring months. It can also be transmitted from direct contact with the open sores. (Clothing, bedding, and such objects do not usually spread the disease.)

A patient with chickenpox can transmit the disease from about two days before the appearance of the spots, to the end of the blister stage. This period lasts about five to seven days. Once dry scabs form, and the disease is unlikely to spread.

Most schools allow children with chickenpox back after ten days of onset. Some require children to stay home until the skin has completely cleared, although this is not necessary to prevent transmission.

Risk Factors for Shingles (Herpes Zoster)

About 500,000 cases of shingles occur each year in the US. Anyone who has had chickenpox has risk for shingles later in life, which means that 90% of adults in the US are at risk for shingles. Shingles occurs, however, in between 10% and 20% of these adult over the course of their lives, so certain factors must exist to increase the risk for such outbreaks.

The Aging Process. The risk for herpes zoster increases as people age, so the overall number of cases will undoubtedly increase as the baby boomer generation gets older. One study estimated that a person who reaches 85 has a 50% chance of having herpes zoster. The risk for postherpetic neuralgia (PHN) is also highest in older people with the infection and increases dramatically after age 50. PHN is persistent pain and is the most feared complication of shingles. An interesting, but small, 2003 study reported that older people with a history of chickenpox who practiced Tai Chi Chih experienced an increase in immune factors against herpes zoster. Tai Chi Chih is an Asian practice that employs balance, alignment, concentration, and meditation. Because Tai Chi and similar practices, such as yoga, reduce stress, these study results suggest that stress reduction techniques might be helpful in reducing the risk for herpes zoster.

Immunosuppression. People whose immune systems are impaired from diseases such as AIDS or childhood cancer have a risk for herpes zoster that is much, much higher than those with healthy immune systems. Herpes zoster in people who are HIV positive may be a sign of full-blown AIDS. The current drugs used for HIV, called protease inhibitors, may also increase the risk for herpes zoster. But drug-associated herpes does not appear to be as severe as it is in AIDS patients.

Cancer. Cancer places people at risk for herpes zoster. At highest risk are those with Hodgkin's disease (13% to 15% of these patients develop shingles). About 7% to 9% of patients with lymphomas, and between 1% and 3% of patients with other cancers, have herpes zoster. Chemotherapy itself increases the risk for herpes zoster.

Immunosuppressant Drugs. Patients who take certain drugs that suppress the immune system are at risk for shingles (as well as other infections). They include:

• Azathioprine (Imuran).
• Chlorambucil (Leukeran).
• Cyclophosphamide (Cytoxan).
• Cyclosporine (Sandimmune, Neoral).
• Cladribine.

These drugs can be used in patients who have undergone organ transplantation, but they are also often used for severe autoimmune diseases caused by the inflammatory process. Such disorders include rheumatoid arthritis, systemic lupus erythematosus, diabetes, multiple sclerosis, Crohn's disease, and ulcerative colitis.

Lack of Exposure to Children Infected with Chickenpox. Interestingly, one study suggested that previously infected adults who are exposed to children with chickenpox may receive an extra boost in antibody production, which can actually help them fight off herpes zoster. This means that as more children are vaccinated against chickenpox, more adults may be at risk for herpes zoster.

Risk Factors for Shingles in Children. Although most common in adults, shingles can also develop in children. One study reported that only 5% of cases occur in those under age 15. Children with immune deficiencies are at highest risk. Children with no immune problems and those who have chickenpox before they were one year old are at higher risk for shingles. It is still uncommon, however.