Chickenpox

Chickenpox is remembered as a week of itching in childhood, and most of the time that is exactly what it is: in a small child the illness sorts itself out, and what is wanted from a doctor is confirmation rather than treatment. The same virus behaves quite differently in a teenager, an adult, a pregnant woman, a newborn or anyone whose immune system is weakened. There the conversation is about pneumonia, about hospital, and about medicines that have to be started on the first day. So talking about chickenpox is mostly talking about who lives alongside the person who has it.

How it starts and what happens to the skin

A day or two before the rash the child is listless, off food, feverish, aching, with a headache. In the youngest that opening act may be missing altogether: parents simply notice the first spots, usually on the scalp, the face or the trunk.

After that every single spot travels the same road, and takes about a day to do it:

• a flat mark, pink, reddish or barely different in colour from the surrounding skin; on brown and black skin it is easier to feel than to see;
• a blister filled with clear fluid, like a drop of dew, which is the itchiest stage;
• a crust, which falls off by itself within one to two weeks.

The giveaway sign of chickenpox is that it arrives in waves. New spots keep appearing for three to five days, so the skin carries fresh blisters and dried crusts at the same time. That mixture of stages is what sets it apart from most other rashes.

The rash does not stop at the skin. It turns up in the mouth, on the tongue, on the eyelids, in the groin and on the genitals, where the blisters break quickly and leave painful ulcers. A child who suddenly refuses to drink or swallow is usually suffering from those. The total count varies enormously: one person gets a dozen spots, another several hundred. In vaccinated children the illness runs faint, sometimes twenty spots and no fever, and then it is easy to miss.

How long a person is infectious

The chickenpox virus is airborne in the fullest sense: sharing a room with someone who has it is enough. The other route is contact with the fluid from the blisters, or with shared bedding and towels.

A person becomes infectious a day or two before the first spot, while nobody suspects anything yet, and stops being a danger once every lesion has crusted over, usually by the fifth or sixth day of the rash. From catching the virus to the rash takes ten days to three weeks, most often about two: if a child brought the infection home from nursery, the story will repeat itself at home a fortnight later.

There is one more source that people forget about: shingles in an older relative. It is the same virus, only reawakened. A child who has never had chickenpox and is not vaccinated can catch chickenpox from contact with those blisters. The reverse never happens: shingles is not caught from anyone, it grows out of a person's own infection that has been dormant for decades.

Staying at home lasts until the day the last blister dries up. If a clinic visit is unavoidable, phone ahead and say so: the waiting room may hold a pregnant woman or someone on chemotherapy.

Who has more to fear from it

The list is short and worth knowing by heart.

• Teenagers and adults have a rougher time than children: higher fever, a heavier rash, and noticeably more pneumonia, especially in smokers.
• Pregnant women. The danger runs two ways: severe pneumonia for the woman herself, and birth defects for the baby if the infection is caught in the first half of pregnancy. A separate and far more worrying situation is a rash in the mother in the last days before delivery or immediately after it, when the newborn has no time to receive her protection.
• Newborns in their first weeks of life.
• People with a weakened immune system: on chemotherapy, on long-term steroids or on medication after a transplant, living with HIV.

If anyone from this list has been in contact with a case and has never had chickenpox, they should seek advice the same day, without waiting for a rash. In the first days after exposure there is still time to give a protective preparation or to prescribe an antiviral. A week later that conversation is pointless.

Signs that will not wait

Ordinary chickenpox is miserable but harmless. What should worry you is anything that does not fit the picture:

• the skin around the blisters turns hot, dusky red, swollen and sharply painful, with pain out of proportion to the rash: that is how a bacterial infection of the soft tissues begins, and it unfolds over hours;
• breathlessness, fast breathing, chest pain, a persistent cough;
• the child cannot be roused, is confused or rambling;
• a seizure;
• the child can no longer walk or sit steadily, sways, misses when reaching for an object: this is inflammation of the cerebellum, which usually passes without a trace but needs to be looked at;
• a severe headache with vomiting, and light that hurts the eyes;
• bleeding into the rash or bruising appears;
• the child has drunk nothing for hours, is passing little urine, has dry lips;
• fever lasting more than four days, or coming back after it had already settled.

The first four points are a reason to call the emergency services, which across Europe means 112; the rest mean being seen by a doctor the same day.

What helps at home

A healthy child needs no treatment aimed at driving out the virus. The task is a different one: to get through the itching without the skin being scratched into scars.

• Drinks in small amounts and often. If swallowing hurts, cold things help: ice cream, ice lollies, chilled drinks.
• Paracetamol at the dose for the child's age, for fever and pain.
• Short nails, and for a baby, mittens or socks over the hands at night.
• A cool bath or shower; afterwards the skin is patted dry with a towel rather than rubbed.
• Loose cotton clothing and a light blanket: warmth makes the itching worse.
• Cooling lotions and gels from the pharmacy, which do not speed up recovery but do settle the itch for a while. About antihistamines by mouth, ask a doctor or pharmacist: they do not suit everyone, or every age.
• Soft food with no salt and nothing acidic, if the mouth is affected.

Antiviral medicines are not given to everybody. They work best when started within the first twenty-four hours of the rash appearing; for people at higher risk they are also prescribed later, within the first three days. They are meant for adults, teenagers, pregnant women, newborns and people with weakened immunity. For a healthy preschooler they add nothing.

What is better left undone

• Giving ibuprofen or other non-steroidal anti-inflammatory drugs. Taking them during chickenpox has been linked with more severe bacterial complications in the skin. Fever is brought down with paracetamol. If ibuprofen has been prescribed by a doctor for something else, that decision stays with the doctor.
• Giving aspirin to children and teenagers. On top of a viral infection it can trigger Reye's syndrome, severe damage to the liver and the brain.
• Scratching. The white sunken scars that last a lifetime are left not by the illness but by scratching and the infection carried into it.
• Painting the spots with coloured dyes. They treat nothing, and under a layer of colour there is no way to see whether inflammation has started.
• Taking the child out "for a bit of fresh air" to someone's house, a shop or the playground before the rash has crusted over.

What the illness leaves behind

Anyone who has had chickenpox is protected from a second attack for life: catching it twice is rare and happens mainly to people whose immunity is badly suppressed. The virus, though, does not go anywhere. It withdraws into the nerve ganglia alongside the spine and stays there for decades. When immune control weakens with age, through illness or through treatment, the virus wakes up and produces shingles: a painful band of blisters on one side of the body.

A chickenpox vaccine exists, is given in two doses and contains live weakened virus. In some countries it is part of the national schedule; in others it is given on request. It protects well against severe disease; catching chickenpox afterwards is still possible, but it usually means a few spots and no fever. The live vaccine is not given to pregnant women or to people with significant immune deficiency, which makes it all the more important that the household around them is vaccinated. A woman planning a pregnancy who has never had chickenpox would be wise to discuss vaccination in advance: once pregnant, it is too late.

Online consultation

In a remote appointment the doctor works out from the description and photographs of the rash whether this is chickenpox, counts up the infectious period and says when nursery, school or work can start again. It is worth booking a separate conversation if the household includes a pregnant woman, a baby or someone on chemotherapy: then the discussion turns to the urgent measures available to them and the window in which those measures still work. The doctor can advise on easing the itch and the fever, on which medicines are best avoided in chickenpox, and on the signs that mean the illness has stopped being harmless and needs examining in person.

This material is for information only and does not replace medical advice.