A top doctor has warned a mumps outbreak is likely to get worse during the summer holidays.

Thousands of holidaymakers and daytrippers are expected to visit Brighton and Hove as the city’s tourism industry prepares for its busiest time of the year.

The city’s director of public health, Tom Scanlon, said it was “more than likely” the number of mumps cases would go up during the next eight weeks.

He said: “The illness is mainly affecting young people in their 20s and there are going to be large numbers visiting the city and going out and socialising.

“Unlike measles, which normally affects schoolchildren and would be likely to show a fall in numbers in the summer because of the holidays, I would expect to see an increase when it comes to mumps.”

There have been 112 confirmed cases across Sussex so far this year and numbers are expected to soon pass the 139 recorded for the whole of 2009.

The worst-hit area is Brighton and Hove, which has had 52 cases so far, almost double the number in 2009.

Thirty nine people have been affected in East Sussex, just three short of the 42 in 2009.

West Sussex has had 21 patients struck down so far, which is lower than the 70 the year before.

However in 2009, there was a large outbreak of cases at Chichester College, which skewed the numbers.

Cases are affecting both young adults and teenagers.

The rise in cases has sparked renewed calls for people to make sure they are vaccinated with the measles, mumps and rubella (MMR) jab.

The take-up rate for the first of two recommended MMR jabs in Brighton and Hove is currently 82% but the percentage having two doses is 69%. This is well below the 90% the World Health Organisation says needs to be vaccinated to protect a community.

Take-up rates are higher in East and West Sussex but there is still room for improvement.

Dr Scanlon said: “It certainly seems as if the numbers of mumps cases are actually spreading around Sussex and not just Brighton and Hove and that is concerning.

“This is a potentially very serious disease and I would urge all those eligible to get vaccinated as soon as possible.”

Those affected are mainly young adults. This may be because the MMR vaccine was not available when they were small.

Othersmay not have had the jab because of concerns about research published in the late 1990s, which suggested a link with autism. This has since been discredited.

In most cases mumps is mild but it can cause serious complications, particularly for men, including sterility, an inflammation of the pancreas, deafness and viral meningitis.

siobhan.ryan @theargus.co.uk