Measles
Measles is a viral infection that spreads more easily than almost anything else people catch.
On this page
- Why measles spreads so easily
- How the illness unfolds day by day
- Telling measles from other rashes, and confirming it
- When to call an ambulance
- When to be seen the same day
- Why measles is dangerous
- Measles in pregnancy
- Looking after someone at home
- Avoiding passing it on
- The measles vaccine
- Online consultation with a doctor
Measles is a viral infection that spreads more easily than almost anything else people catch. Most recover within a couple of weeks, but a proportion are left with complications affecting the lungs, the ears and the brain, which is why no country treats it as a harmless childhood illness. There is no medicine that kills the virus. There is, however, reliable protection: two doses of the combined vaccine against measles, mumps and rubella.
Why measles spreads so easily
The virus is released when someone breathes, talks, coughs or sneezes, and it lingers in the air of a room for about two hours after that person has left. You can catch it simply by walking into a consulting room or a shop behind them, without ever meeting face to face. If someone who has neither been vaccinated nor had measles spends time near a case, they will almost certainly catch it.
A person is infectious before the rash appears, from roughly four days beforehand, when everything looks like a heavy cold, and stays infectious for four days after the rash comes out. That is how measles spreads through a nursery, a school or a waiting room before anyone works out what they are dealing with.
The gap between catching the virus and the first symptoms is usually one to two weeks, occasionally longer. Throughout that time the person feels perfectly well.
How the illness unfolds day by day
Measles follows a fairly constant script, and knowing the order helps you suspect it sooner.
The first three or four days resemble a bad cold: a high temperature, a streaming nose, a dry barking cough and sneezing. What sets measles apart is the eyes. They become red and watery and light feels unpleasant.
A day or two before the rash, tiny whitish spots appear on the lining of the cheeks opposite the back teeth, like grains of semolina on a reddish background. These are Koplik's spots, a sign seen in measles and nothing else. They do not last long, so look inside the mouth in daylight.
The rash starts behind the ears and on the face, moves down to the trunk and arms the next day, and reaches the legs the day after. The spots are large and slightly raised, tend to merge into irregular patches, and usually do not itch. On pale skin they look red or brownish; on brown and black skin they are harder to see, so go by touch and by the rash behind the ears.
The temperature rises again at the height of the rash, and that is expected. After three or four days the rash fades in the same order it appeared, leaving brownish staining and fine peeling. The cough and the tiredness are the last things to go, sometimes lasting a fortnight.
Telling measles from other rashes, and confirming it
Plenty of illnesses cause a rash with a fever: rubella, parvovirus infection, enteroviruses, scarlet fever and drug allergy all look similar. What points to measles is the combination of red watery eyes with a persistent cough before the rash, the strict sequence of face, trunk and legs, and the fact that the person does not feel any better once the rash is out. Two doses of vaccine, or measles in the past, make the diagnosis unlikely, though someone who has had only one dose can still get a mild, muted version of it, and they are infectious too.
The diagnosis is therefore confirmed in the laboratory, and this is done every time, even when the picture looks obvious. A throat swab or a saliva sample is taken to detect the virus by PCR, sometimes with a urine sample as well. In parallel, blood is tested for IgM antibodies: in the first days of the rash these may not yet be detectable, so an early negative result is repeated.
Measles is one of the infections a doctor is required to report to the public health service. This is not paperwork for its own sake: it is how contacts are traced and protected before they fall ill. Try to remember accurately where you have been over the past few days.
When to call an ambulance
Call an ambulance (across Europe the single number is 112) or go to the emergency department if any of the following appears:
- difficulty breathing: gasping for air, speaking only in single words, or in a baby, grunting and the spaces between the ribs sucking in;
- a fit or seizure;
- a child who cannot be woken, will not hold your gaze, whose head flops back and whose body has gone limp;
- confusion, strange behaviour, or crying that will not stop;
- severe headache with vomiting, discomfort in bright light, or an inability to bring the chin down to the chest;
- a rash that does not fade when a clear glass is pressed against it;
- signs of dehydration: dry lips and tongue, no tears, little urine, a sunken fontanelle in a baby.
Driving yourself in that state is a bad idea: you need someone who can help on the way. Take a list of any medicines being taken.
When to be seen the same day
An ambulance is not always needed, but sitting measles out at home without telling anyone is not an option either. Contact a doctor the same day if you suspect measles in yourself or your child; if the temperature lasts more than four days after the rash appeared, or climbs again once things were improving; or if there is earache, discharge from the ear, breathlessness, chest pain, or an eye that hurts and sees less well.
Phone before you go and say that you suspect measles. You will be taken past the general waiting area so that nobody else is exposed, particularly babies and people whose immune system is weakened.
Why measles is dangerous
Complications affect roughly one in ten to fifteen of those infected, and most occur in children under five, adults, pregnant women and people with weakened immunity.
- Middle ear infection, the commonest of all; it sometimes leaves permanent hearing loss.
- Pneumonia, either viral or a bacterial infection on top, which is the leading cause of death from measles.
- Croup: swelling of the voice box with a harsh cough and noisy breathing.
- Diarrhoea with dehydration, particularly in small children.
- Damage to the cornea, occasionally leading to blindness, most often where vitamin A is lacking.
- Encephalitis, inflammation of the brain, in around one case per thousand; it causes fits and confusion and can leave lifelong effects.
There is also a late complication worth knowing about: subacute sclerosing panencephalitis. It develops several years after recovery, mostly in those who had measles in the first or second year of life, is very rare and cannot be treated. Measles also strips the immune memory for months afterwards: the body partly forgets infections it was already protected against, and during that period people catch other illnesses more often and more severely.
Measles in pregnancy
Pregnant women have a harder time of it: pneumonia is more common and admission to hospital is more often needed. The infection raises the risk of miscarriage, stillbirth, premature birth and low birth weight. Measles does not cause birth defects the way rubella does, but if labour coincides with the height of the illness the newborn can become seriously unwell.
The vaccine contains live virus and is not given during pregnancy, so protection is built beforehand, before conception. If an unprotected pregnant woman has been in contact with a case, she should contact a doctor at once: immunoglobulin given in the first days after exposure helps. Breastfeeding is no barrier to vaccination, and it is given after the birth without delay.
Looking after someone at home
There is no medicine against the virus itself, so home care has two aims: keeping the person comfortable and catching a complication early.
Fluids matter most, because fever and sweating dehydrate quickly. Offer water, weak squash or an oral rehydration solution little and often, and keep an eye on how many wet nappies or trips to the toilet there are. Paracetamol or ibuprofen at a dose appropriate to age and weight will help the fever and aches; aspirin is not given to children and teenagers with a viral illness. Draw the curtains if light bothers the eyes, and gently wipe crusts from the eyelids with cotton wool dipped in cooled boiled water.
Air the room but do not let the air get too dry, as dry air makes the cough worse. There is no need to push food. Doctors often prescribe vitamin A for children with measles, since it lowers the risk of severe illness and eye damage, but the dose is a matter for the doctor and it should not be given on your own initiative. Antibiotics do nothing against the virus and are used only when a bacterial infection is added on top.
Avoiding passing it on
Stay at home and away from nursery, school and work for at least four days from the appearance of the rash, and ideally until you feel well. It matters most to keep away from babies too young to have been vaccinated, from pregnant women, and from anyone whose immunity is suppressed by illness or treatment: measles is most dangerous for them, and they often cannot be vaccinated.
At home, air the rooms often, wash hands, cover your mouth with a tissue when coughing and bin it straight away, and do not share crockery, towels or bedding with the person who is ill.
Let everyone who has been near the case in recent days know. If they are unprotected, vaccination within the first seventy-two hours after contact, or immunoglobulin over the following days, can prevent the illness altogether or make it much milder, but only if they act immediately.
The measles vaccine
Vaccination is the only reliable way of not catching measles. It is given as the combined vaccine against measles, mumps and rubella; in some countries the same preparation also covers chickenpox.
The full course is two doses: the first in the second year of life and the second later, at pre-school or early school age. The exact ages are set by the national immunisation schedule of your country. Two doses protect nine or ten out of every ten people vaccinated, and that protection appears to last for life.
Catching up is possible at any age: adults with no record of vaccination and no history of measles are given two doses a few weeks apart. Because it is a live vaccine, it is not given in pregnancy or where immunity is markedly suppressed, and in those situations a doctor will suggest another approach. The usual side effects are a mild temperature and a faint rash a week to ten days later, which settle on their own. There is no link between this vaccine and autism: the paper that started the claim was shown to be fraudulent and withdrawn, and later studies covering millions of children found no association at all.
Online consultation with a doctor
Where measles is suspected, an online appointment has one obvious advantage: nobody has to take an infectious person into a shared waiting room. The doctor will ask in what order the symptoms appeared, ask to see the rash and the lining of the cheeks in daylight, assess the breathing and the general state, and say which tests are needed and where to go to have the diagnosis confirmed. Online is also the place to go through results, sort out home care, work out how long isolation should last and what household members and colleagues should do, and arrange catch-up vaccination for adults. If any of the signs listed under calling an ambulance appear, do not wait for an online appointment.
This material is for information only and does not replace medical advice.
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