Measles

What is measles?

Measles is caused by a virus that is spread by droplets. The virus is passed on through direct contact with someone who's infected, for example by touching or kissing them, or through breathing in contaminated air. It's fairly easy to catch if you haven't been vaccinated and come into contact with someone who has the infection, which is why epidemics often occur among schoolchildren.

The infectious period is from around four days before the appearance of the rash, to around four days after its appearance. Unfortunately, it's most infectious before the rash is visible so people tend to spread the virus before they realise they have it.

Who's at increased risk of measles?

• Babies under one year
• People whose immune system is suppressed, for example by cancer or HIV
• Malnourished people
• Children with vitamin A deficiency
• Pregnant women - the infection may cause miscarriage or premature delivery

Who's affected by measles?

Although people of any age can get measles, it's most common among those aged between one and four.

All children who have not been vaccinated are at risk from measles, and those who have problems with their immune system (particularly with T lymphocytes) may have a more severe case of measles.

What are the symptoms?

Symptoms take about ten to 14 days to develop after exposure to the virus (the incubation period). Early symptoms are like a cold, with runny nose, cough, conjunctivitis and fever.

A couple of days later, tiny white spots surrounded by red (Koplik spots) may develop on the inside lining of the cheeks, so they are difficult to see.

The measles rash appears a day or two later, starting behind the ears or on the face and spreading down across the body. It's a fine red rash which becomes blotchy and confluent, fades after three to four days and may peel off after a week or so.

Abdominal symptoms may include nausea and vomiting, abdominal pain and diarrhoea. Symptoms usually last about 14 days in all and it's recommended that children stay off school for five days after the start of the rash.

The infection isn't usually serious but there are potential complications that can be fatal, even for otherwise healthy children. These include otitis media, pneumonia, hepatitis, conjunctivitis and encephalitis (inflammation of the brain, which occurs in about one in 5,000 cases).

Although complications involving the nervous system occur in fewer than one in 1,000 cases, the long-term effects can be devastating.

Encephalitis or inflammation of the brain may develop a few days after the rash has appeared, and a quarter of those who get this complication will be left with brain damage. A devastating but extremely rare progressive illness called subacute sclerosing panencephalitis (SSPE) may develop many years after the first bout of measles and is eventually fatal. Fortunately, it's very rare, occuring in fewer than one in 100,000 cases.

What's the treatment for measles?

See your doctor to confirm the diagnosis. Children may be treated at home with pain and fever-reducing syrups such as paracetamol and they should be encouraged to drink fluids.

Hospital treatment, with antiviral drugs, may be needed in more serious cases. In developing countries vitamin A may also be given to help the immune system.

Although rare, complications can be very dangerous. Encephalitis, for example, typically develops after about eight days, with headaches, lethargy and irritability, progressing to convulsions, coma and death in 15 per cent and long-term health problems in nearly half of survivors. If your child shows any worrying symptoms during measles get urgent medical advice.

The child is infectious from one day before the onset of symptoms until about four days after the start of the rash, so let friends, family and other potential contacts know.

Measles vaccination

Children in the UK are offered vaccination against measles as part of the MMR vaccine, which is given to them between 12 and 15 months of age (with a booster dose before they start school).

If a baby under six months, who has yet to be immunised, is in contact with measles, they'll be protected by antibodies passed to them in the womb. If the mother didn’t have measles or the vaccination in her childhood, the baby may be given an injection of antibodies (human normal immunoglobulin, HNIG) which offers short-term but immediate protection against the measles virus.

However, if a baby over six months is in contact with measles, they'll be offered a measles vaccination early to protect them , as well as receiving the usual injection at 12 to15 months and the pre-school booster.

There's been concern about possible risks from vaccination, especially with the combined MMR vaccine, after several researchers (including one at the London's Royal Free Hospital) suggested links with either autism or Crohn's disease.

The overwhelming body of evidence doesn't support these worries and most experts are emphatic that the MMR vaccine is safe and effective, preventing illnesses whose real potential to cause damage most parents have lost sight of. These infections cannot be beaten in any other way.

Don't forget, the child is infectious from around two to four days before the rash appears to around four days after, so let friends, family and other potential contacts know.

The facts about measles

• Measles can, and does, kill and do long-term harm but vaccination prevents this risk
• Measles is a notifiable disease - if you think your child may have it, see your doctor at once, who can confirm the diagnosis with a simple saliva test who and must then let the local health authority know
• Some children may possibly be at risk from vaccination - for example, a child who's had febrile fits or existing nervous system problems
• A vaccine for each infection may be given instead of the MMR vaccine in certain cases, for example, if your child has an allergy, but it's extremely difficult to get hold of the separate vaccines
• Ask your GP for advice if you think your child may be at risk from the vaccine