SHINGLES or herpes zoster is a skin condition characterised by vesicles or “water bumps” on a section of the skin supplied by a specific nerve in a dermatomal distribution.

Though it occurs in people with an intact immune system, especially those over 60 years old, older patients with weak immune systems are more at risk.

Shingles is caused by the varicella zoster virus, a deoxyribonucleic acid (DNA) herpes virus. Initially a separate infection occurs through droplets in the air containing the virus. The viral particles come into contact with the mucosa of the mouth and nose and travel in the blood, then it grows and multiplies in the body. After the viral infection overwhelms the immune system, it results in a vesicular rash all over the body called chicken pox. This happens in approximately 14 days, during which the virus infects and eventually lives dormantly in certain nerve cell bodies.

When they are reactivated later, the result is a painful blistering rash known as shingles. Reactivation typically occurs in people with weakened immune systems that can no longer contain the virus, so it multiples.

WHO IS AT RISK?

Those at risk include the elderly who have weak cellular immunity, diabetics, cancer patients, those infected with HIV/AIDS, patients on steroids, or who have had an organ transplant, and those on immuno-suppressive drugs. Shingles occurs mainly in the nerve that supplies sensation to the face and trunk.

WHAT TO LOOK FOR?

Shingles presents with a red rash that quickly develops into a group of vesicles or larger ones called bullae. Within a week, the clear-filled rashes become replaced with pus and then form crusts — yellow, dried rashes. Healing may take up to a month and then a darkened area develops which may be present for months. Some patients may also have fever, headache and tiredness along with the rash.

If the patient has a weakened immune system, several nerves may be affected, so several sections of the skin will have the painful rash. These people can also have inflammation involving the lung, liver and brain, which may precede the rash and is often missed.

DIAGNOSIS

The doctor will diagnose shingles based on the symptoms and the rash. However, lab tests may become necessary if the diagnosis is doubtful. Polymerase chain reaction (PCR), although expensive, can test for the viral DNA in the fluid from the skin rash, blood, brain, or lung fluid.

Shingles is contagious and can be transferred from person to person by air droplets or contact with infected skin. Covering the lesion reduces the likelihood of passing on the virus.

TREATMENT

Treatment of shingles focuses on reducing the duration of the illness and preventing complications. These complications include pain, numbness and abnormal sensation persisting after the rash termed post-herpetic neuralgia; eye involvement that could threaten sight, especially if there is a vesicle at the tip of the nose and bacterial infections causing severe skin infection.

Antivirals can reduce the inflammation of the nerves and decrease the healing time. Antidepressants, medications such as gabapentin, topical anaesthetics and opioids are used to treat the nerve pain associated with the disease.

Patients who have eye involvement should see an ophthalmologist. Antiviral and topical steroids are also used by the specialist to treat some of the eye complications.

A zoster vaccine is approved for people at risk of developing shingles, but there are specific requirements, especially if there is the presence of a weakened immune system.

Dr Romayne Edwards is a consultant emergency physician at the University Hospital of the West Indies and an associate lecturer at the University of the West Indies.