MORE than 1000 people have fallen ill with whooping cough in Scotland and the outbreak is expected to get worse.

Figures just released show GPs have reported 1020 cases since the start of the year, compared to 43 for the same period in 2011.

Although the speed with which the infection is spreading appeared to reduce during the last month, experts at surveillance agency Health Protection Scotland (HPS) said this may be linked to school and university holidays. As young people return to classrooms and lecture halls more people may contract it.

Dr Martin Donaghy, medical director of HPS, said: "It may have slowed down in recent weeks. Usually what we find with respiratory infections is the rate of transmission in the community often corresponds with things like schools and university depending on the age group.

"When we have more concentrated social mixing, particularly in enclosed spaces, transmission picks up again."

Whooping cough, also known as pertussis, usually begins with mild cold symptoms. It then develops into coughing fits which can be severe. The cough can last for three months and the illness is known as the "100 day cough" in some countries.

Outbreaks are known to occur in cycles and experts believed another one was due, but its speed and scale has exceeded expectations. The number of cases in Scotland is at the highest level for at least 25 years.

Babies are at particular risk from whooping cough because their lungs are small, and although they are first vaccinated at eight weeks they remain vulnerable until they have received three doses of the vaccine.

This year 49 people have been admitted to hospital with whooping cough in Scotland, including 28 who are less than one year old.

However, no-one is reported to have died from the illness. In England, which is also affected by the outbreak, six babies under the age of three months have died.

Dr Donaghy said: "People who have symptoms should be very careful when they are coughing around infants in case they transmit it. They should make sure they cover their mouths and, if the cough is persistent, visit their GP.

"We are advising parents to make sure new babies start their immunisations as near as possible to reaching eight weeks of age."

So far, laboratory tests have confirmed 83 cases of whooping cough in children under the age of one in Scotland, of which 58 were younger than three months.

A decision on whether pregnant women should be given the whooping cough vaccine in order to offer some protection to newborn babies is expected shortly.

The Joint Committee on Vaccination and Immunisation is also considering whether to offer teenagers a booster vaccine. The effect of immunisation is known to wear off in adolescence.

It is thought one of the reasons for the current outbreak is the number of people no longer immune and the number of people infected has reached a tipping point, where the spread of the illness has become likely.