Chlamydia can cause infertility

Posters are being put up at colleges, the county's university is urging students to get screened, and self-test kits will be available.

Figures show about 10% of under-25s tested have the disease.

It can be treated with antibiotics, but if left unchecked it can lead to pelvic inflammatory disease, ectopic pregnancy and infertility.

No symptoms.

Nicki Saulsbury, a consultant in genito-urinary medicine at the Royal Cornwall Hospital, said: "It's a big problem. We know there is a large number of young people who are not aware of our services or of the problem.

"Most of the time people don't know they have it because 80% of women and 60 to 70% of men will have no symptoms. So, unless you get tested, you don't know."

Sheila Hutchins, head of student services at the University for Cornwall campus at Tremough, agreed that awareness was part of the problem.

She said: "Most young people think 'it isn't going to happen to me', so we need to raise the fact that it could.

"We also need to persuade people that it's sensible to think about sexual health, that it's nothing to be ashamed of, and is sensible and positive."

The Department of Health programme is being piloted in Cornwall and London.