Measles rates in Britain are more than five times higher than last year. London is one of the worst hit areas partly because the rates of vaccination are lower.

There have also been some small clusters associated with schools, universities and family groups, including a nursery school in Wales and a private school in Devon. So what can you do to protect your family?

‘The increase in cases is mainly because of contact with people in France and other European countries, where there has been a rise in measles cases,’ says Dr Ramsay.

France has many of the cases reported this year. This has been blamed on a low uptake of the jab in the country, which dates back to the early Nineties. It’s thought the disease is being spread in Britain by families who have gone on holiday in Europe.

Children in the ten to 17 age group have mainly been affected. This has been linked to the drop in vaccine uptake ten to 12 years ago following Andrew Wakefield’s (highly controversial) research linking MMR to autism.

Measles is ‘one of the most infectious diseases known to Man — you can catch it just by passing someone who has been infected in the street,’ says Dr Ramsay.

‘The illness is spread by inhaling droplets that have been coughed or sneezed into the air by someone infected by the virus. Patients with measles are infectious for four days before their rash develops and four days afterwards.’

Dr Elliman says: ‘Even if you stayed indoors, you would have to check that all family members had immunity. But even then, people such as the postman knocking on the door could spread it because it’s so easy to catch.’ Vaccination remains the key form of protection.

The measles vaccine wasn’t introduced until 1968, but most adults born before then won’t catch the disease ‘because they will have natural immunity having caught it in their childhood,’ says Dr Elliman.

However, those born between 1970 and 1979 may be at risk from infection because they were not immunised.

This is because the uptake of the vaccine remained low in the Seventies and early Eighties, until the convenient triple jab was introduced in 1988.

A catch-up campaign was carried out in schools in 1994, but only for those aged five to 16 at the time. Dr Elliman says those aged between 31 and 41 should consider being vaccinated.

‘If your child was vaccinated at the age of two and had the pre-school booster (usually given at the age of three-and-a-half), they don’t need to be vaccinated again as the first shot gives 90?per cent protection and the second shot 99?per cent,’ says Dr Ramsay.

‘You would have to be very unlucky to catch measles if you’ve been vaccinated.

‘The antibodies give you lifelong protection from the illness.’

Most measles cases have been in children and adults who have not been vaccinated, so the official advice is to get your child or teenager the jab at your local GPs’ surgery.

‘If your child had only one MMR and you are travelling abroad, it may be advisable to have the booster shot,’ says Dr Ramsay.

The vaccine takes effect within six to ten days.

‘The virus starts with a rash inside the mouth that looks similar to sugar or salt granules,’ says Dr Elliman.

‘Then, a red raised rash starts at the hairline and travels down the body. It isn’t painful or itchy.

‘Patients feel very poorly — we call it the “measles miseries” because you feel miserable and unwell. There is also a high temperature, itchy eyes, conjunctivitis and a dry cough.’

As the rash fades after four to five days, it will leave a temporary brown stain, but this won’t scar.

Complications can include pneumonia and ear and eye infections. One in 100 people will have a convulsion, though this mainly affects children.

Around one in 1,000 people develop encephalitis — swelling of the brain — which can be fatal in some cases.

‘Measles symptoms tend to be more severe in adults, as they are with other diseases such as chicken pox,’ says Dr Elliman.

‘If you suspect your child or teenager has measles, you should inform your GP — but don’t go to the surgery or hospital because measles is highly infectious,’ says Dr Elliman.

‘The illness usually passes in a few days, but you should give your child infant paracetamol such as Calpol if they are uncomfortable.’

Complications include breathing difficulties. Other symptoms of complications include refusing to drink, coughing up sputum, sensitivity to light, severe headaches or just not getting any better after three to four days.

In these cases, seek urgent medical advice, says Dr Elliman.