Khalid Javed: Patients are urged to be on the lookout for the disease

In the past three years the number of cases of meningococcal meningitis in teenagers has more than doubled.

Three teenagers have died in the last week following two outbreaks of the disease in South Yorkshire and Tyneside. A third teenager is reported to be in a stable condition in hospital in Rotherham.

Dr Robert Booy: "Being a teenager is stressful"

One of the main theories that will be studied is the idea that stress increases susceptibility to contracting the disease.

Dr Robert Booy, a lecturer in paediatrics at St Mary's Hospital, London, said previous studies had concentrated on young children and not teenagers.

"We will be looking at things like their social behaviours, like smoking, like kissing, going to parties. We are looking at the stresses they undergo like the psychological factors of leaving home and going to university.

"We will also be looking at biological factors."

Teenage years are stressful

Students seem particularly at risk

Dr Booy said being a teenager was a very stressful, with big changes in social circumstances being mirrored by significant biological changes in the body.

He said: "It is an extremely stressful time. Relationships start and sometimes abruptly finish."

Dr Booy said previous research had suggested that stress was a factor in increased susceptibility.

Approximately 50% of cases of meningococcal meningitis occur in children under five. There is then a trough before an upsurge of cases in adolescents aged 15 to 19.

The researchers will look at two groups of teenagers, one affected by meningococcal disease and the other group not affected.

Blood samples will be collected from teenagers admitted to hospital with meningococcal disease and from a healthy person of the same sex and age, selected as a control who is registered with the same GP as the patient.

Dr Booy said teenagers should look out for each other. If a friend had 'flu symptoms they should be closely monitored.