The infection is becoming more common, particularly among young people, but few people are aware of its existence.

If left untreated the infection can cause infertility and miscarriages.

The Health Education Authority will target students by running the campaign in association with the National Union of Students.

The silent sexual infection

Chlamydia infection is caused by the Chlamydia trachomatis bacterium. It can be passed on during vaginal, oral, or anal sexual contact with an infected partner.

Condoms can prevent infection

Pregnant women can pause to newborn children during delivery.

This can lead to the infant suffering an eye infection - which could result in blindness - or pneumonia

The infection can be treated with antibiotics but many cases go undetected because symptoms do not always appear.

The Who's Chlamydia? campaign refers to it as "the silent sexual infection".

It will use posters and information cards to raise awareness of the risks.

Student welfare officers will also be given advice on how to offer advice and support.

Poor awareness

Figures from the HEA show that less than a third of those aged 16 to 24 have heard of the disease.

This compares with 80% who have heard of genital warts and 90% who have heard of HIV, herpes and hepatitis B.

Yet the Public Health Laboratory Service shows that incidence of the disease among the young has risen by 56% over the last two years.

PHLS figures for 1997 show there were 22,000 new cases of infection in this age group.

Last year a report from the chief medical officer recommended that all sexually-active young women should be tested for chlamydia when they saw their doctor.

However, only a handful of GP clinics offer the service automatically, although the number is increasing.

At the moment women usually have to request a test if they request one at a sexual health clinic.

'Serious consequences'

Marie Goldsmith is a project manager at the HEA.

She said: "Anyone who has unsafe sex can get chlamydia if their partner has the infection, but there are usually no symptoms so most people don't know they have got it.

"The long-term consequences can be very serious, such as infertility or ectopic pregnancy.

"But if it's diagnosed early enough it can be treated with antibiotics.