Herpes Zoster: What Kind of Virus Is It and Why Does Shingles Occur

Herpes zoster, zona and shingles are names for one disease: an infection caused by the varicella zoster virus. The same virus causes chickenpox and, years later, can reactivate, producing a painful rash along the course of a nerve. Below is what is known about the infection and when a doctor is needed.

What herpes zoster is and why it is called shingles

Shingles (herpes zoster) is an infection with a painful rash. The name "shingles" describes the typical picture: the rash runs in a band along one side of the body — the left or the right, but not both at once. Most often it is the chest and abdomen, but the rash can also occur on the face, around the eyes, and on the genitals.

First spots appear, then itchy fluid-filled blisters; after a few days they dry out and become crusted — usually within 7–10 days. The skin may hurt for weeks after the rash disappears, and everything heals completely within up to 4 weeks.

The rash usually appears a few days after the first signs: tingling or pain in an area of skin, headache, malaise. In rare cases there is pain without a rash. Fever, chills, and upset stomach are possible.

Varicella zoster virus: the link to chickenpox

The causative agent is the varicella-zoster virus (Varicella Zoster virus), also known as human herpesvirus type 3: a DNA-containing virus of the herpesvirus family.

One virus causes two diseases. Primary infection causes chickenpox — more often in children. After recovery, the virus does not disappear: it remains in the ganglia of the trigeminal nerve and the dorsal roots of the spinal cord. Years later it can reactivate — this is how shingles arises, an endogenous infection in adults who had chickenpox in childhood.

Why the virus reactivates and who is at risk

The trigger is a weakening of immune control: stress, certain diseases, treatment that suppresses immunity, such as chemotherapy. The risk increases with age, and shingles is more common in people over 50.

The lifetime risk is estimated at 20–30%, that is, in 1 in 4 people; for people aged 85 and older — up to 1 in 2. A 2015 Swedish study: 315 cases per 100,000 residents of all ages and 577 per 100,000 among people aged 50 and older. Repeat episodes are possible but rare.

• people over 50;
• patients with immunodeficiency, including HIV;
• people with certain types of cancer;
• those taking steroids or medications after organ transplantation;
• people under stress or with another infection.

A vaccine against shingles exists; it is recommended for older people and patients with weakened immunity, and the decision is made by a doctor.

Is shingles contagious and to whom

Shingles itself is not contagious: you cannot catch it from another person. But the fluid in the blisters contains the virus, so a person with weeping rash can be a source of chickenpox for those who have not had it and are not vaccinated. The virus is not transmitted before the blisters appear or after the rash has crusted over.

The risk is small if the rash is covered by clothing or a loose bandage. While the rash is weeping, it is better to avoid contact with pregnant women who have not had chickenpox, people with weakened immunity, and children under 1 month of age.

What complications are possible

Most people recover without consequences. The most common complication is postherpetic neuralgia: pain persists after the rash disappears, usually resolving over weeks or months, but in 10–15% of cases it lasts longer than three months, and in some people — for years.

Other complications: infection of the rash (sometimes antibiotics are needed), scars and skin discoloration, muscle weakness, eye involvement up to vision loss, Ramsay Hunt syndrome with facial nerve involvement, weakness on one side of the face, and sometimes hearing problems. Very rarely — pneumonia, encephalitis, death.

How the diagnosis is made and when to see a doctor

The diagnosis is usually made by history and examination of the rash. In some cases a tissue scraping or a swab of fluid from the blisters is taken and sent to the laboratory: tests for chickenpox and shingles exist.

See a doctor as soon as possible, preferably within the first 3 days after the rash appears: antiviral drugs prescribed within this period are more effective and reduce the risk of long-term problems. Urgent attention is required for pregnancy; breastfeeding with a rash on the breast; rash on the eye or nose; changes in vision; severe immunodeficiency; age 17 and younger.

The rash of shingles itself is not a reason to call an ambulance; 103 or 112 — if changes in vision appear or the person is very unwell and their condition is rapidly deteriorating.

This material is for reference and does not replace consultation with a doctor, who assesses the specific case.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer