Many of my female friends have been complaining lately that they have been diagnosed with herpes zoster. What causes this condition and how best can it be prevented or treated? Alice

Dear Alice,

Herpes zoster or shingles is a virus infection, affecting the nerves and causing their inflammation. It occurs due to reactivation of chicken pox virus lying dormant in the body. This virus may be present in the body, following an episode of chicken pox or subclinical infection, where virus enters the body but causes no sickness. Why the virus is reactivated is not known precisely, but older people and those with reduced immunity are more prone to it. People affected by chicken pox before 18 months of age are more susceptible to develop herpes zoster later in life.

Chicken pox is spread by coming in direct contact with the virus in skin lesions or saliva or pus from skin lesions. It can also spread as droplet infection. But herpes zoster is not contagious like chicken pox.

It typically starts as severe burning pain on the site of affected nerve, which can be one side of the face, chest or any part of the body. In immune suppressed people it can be bilateral or extensive. Sometimes, the nerve supplying the eyes can be affected causing visual problems. There may be associated tingling and or numbness. This is followed in 2-3 days by appearance of vesicular eruptions, which later on become filled with pus, dry up and then fall. This entire process takes 7-10 days. In some people, the pain subsides in this period, whereas in some it continues for 4-12 months due to residual inflammation of the nerve.

Diagnosis is made easily, based on symptoms and physical examination. It can be confirmed by polymerase chain reaction or demonstration of virus by nerve biopsy.

Primary prevention consists of strengthening the immune system. Protection against chicken pox by adopting good hygienic measures while dealing with a patient can protect against herpes zoster later in life. CDC(Center for disease control and prevention recommends unique dose of herpes zoster vaccine to people above 60 years and those who are prone. It provides effective prevention against shingles for 3-5 years.