By Shannon C. Pickens, M.D.
Herpes zoster (shingles) is a painful, blistering skin rash due to the varicella-zoster virus, the virus that causes chickenpox. Once an episode of chickenpox has resolved, the virus remains inactive in certain nerves in the body. Shingles occurs after the virus becomes active in the nerves years later. Years later, the virus may break out of the nerve cell bodies and travel down nerve axons to cause viral infection of the skin in the region of the nerve; this region is called a dermatome. In some people, it stays dormant forever; in others, the virus becomes active when disease, stress or aging weakens the immune system. However, many patients with zoster apparently have normal immune systems.
Many people question whether or not a person can catch the shingles from someone else who has the shingles. You cannot catch shingles from someone else who has shingles, but a person with a shingles rash can spread chickenpox to a person who has not had the chickenpox or has not gotten the chickenpox vaccine. The virus is spread through direct contact with fluid from the rash blisters, not through sneezing, coughing or casual contact. A person is not infectious before the blisters appear or after the rash has developed crusts.
The incidence rate of herpes zoster every year ranges form 1.2-3.4 cases per 1,000 healthy individuals of all ages and increases to 3.9-11.8 per 1,000 individuals greater than 65 years old. Approximately 10-20% of the U.S. population eventually develops one or more cases of zoster. The incidence of people who are immunocompromised is much higher, probably closer to 50%.
The earliest symptoms include headache, fever and malaise followed by burning pain, itching, tingling and/or numbness. This is followed by a rash usually limited to a single dermatome on one side of the body that does not cross the midline. The rash begins as red patches, which then form small blisters. The blisters eventually fill with fluid and then crust over. It takes two to four weeks for the blisters to heal, and they may leave scars.
Herpes zoster is usually diagnosed clinically. A scraping may reveal giant multinucleated cells, but these are not specific for herpes zoster. These giant cells have also been seen in herpes simplex, which causes a rash that is often indistinguishable from the rash caused by herpes zoster. General laboratory studies and other systemic workups are not indicated unless complications or underlying disease are suggested.
Treatment for the rash usually consists of antiviral medications which are used to help reduce pain and complications and to shorten the course of the disease. Examples include acyclovir, famcyclovir and valacyclovir. An antiviral drug treatment can reduce the severity and duration of herpes zoster if a seven to 10-day course of the drug is started within 72 hours of the appearance of the characteristic rash. Cool wet compresses, oatmeal baths and calamine lotion may reduce itch and discomfort.
The rash usually clears in two to three weeks and rarely reoccurs. Sometimes, the pain in the area where the shingles occurred may last from months to years; this is called post herpetic neuralgia (PHN), and it occurs when nerves have been damaged by an outbreak. PHN occurs rarely in people under 40 years old but can occur in up to half of untreated people who are 60 years and older. Other complications include herpes zoster ophthalmicus, which involves the orbit of the eye and occurs in about 10-25% of cases; if this occurs, it may cause loss of vision. Herpes zoster oticus (Ramsay Hunt syndrome) involves the ear secondary to the virus spreading to the vestibulocochlear nerve and may cause hearing loss and vertigo. Occasionally, herpes zoster can become widespread and is disseminated over the entire body. It is usually indistinguishable from varicella (chickenpox) and almost always occurs in the immunocompromised.
A live vaccine for VZV exists and is marketed as Zostavax. It prevents half of the cases of herpes zoster in older adults and reduces the cases of PHN by two thirds. In October 2007, the vaccine was officially recommended in the U.S. for healthy adults age 60 and older. It can cut the risk of severe disease by 55%. It is not recommended to treat active shingles or post herpetic neuralgia once it develops. You should not get the vaccine if you have had an allergic reaction to gelatin, neomycin or have a weakened immune system secondary to HIV/AIDS, treatment that affects the immune system such as steroids, cancer treatment or have a history of cancer; women who are pregnant should not receive the vaccine.
To learn more about Herpes Zoster, visit https://www.mayoclinic.org/diseases-conditions/shingles/symptoms-causes/syc-20353054