Over recent weeks in Sheffield there have been a number of cases of measles.
Since the introduction of MMR vaccine measles has been rare in the UK.
However, a dip in immunisation rates, linked with worries people had about risks, has lowered the level of immunity and outbreaks of measles sometimes occur.
Measles is a very infectious viral illness.
The first symptoms usually develop around 10 days after being infected and can include flu type symptoms with runny nose, sneezing and a cough.
The eyes may be red, feel sore and be sensitive to light.
The temperature can go very high and people can feel really unwell in themselves.
A few days later a blotchy red/brown rash appears.
The rash starts on the head or upper neck and spreads downwards over the body.
Risk of infecting others is greatest from four days before the rash comes to four days after it appears.
Most people recover well after seven to 10 days, but occasionally there can be more serious problems such as pneumonia and people sometimes need hospital admission.
In the UK most children have two doses of the MMR vaccine which makes them immune to measles.
Most people born after 1970 have immunity through having measles as a child.
If you think you may have measles it is important to seek help, while not spreading the virus to others inappropriately.
If you ring your GP they may advise that you do not come to the surgery, unless there is a clinical need.
Whn you are seen it will most likely be at the end of a surgery and you will be asked to sit in a side room.
If you have to wait more than a few minutes you may be asked to wear a mask and the doctor seeing you may also wear a mask, gloves and apron.
In Sheffield we have an excellent infectious diseases department at the Hallamshire Hospital and the team there see anyone who needs to be referred with severe symptoms or complications of measles.
Perhaps the most important message is to make sure children have their vaccinations.
There are many illnesses we rarely see now because of the effectiveness of vaccines.
It is only when outbreaks occur, and people realise how nasty infections like measles can be, that we remember the importance of vaccination and the benefit we have in our country from vaccines offered.