Teenagers are being offered a free postal chlamydia testing service in a bid to halt the increase in the sexually-transmitted infection (STI).
The Dorset Sexual Health team is releasing the DIY kits - called Not For Virgins - to cut the rise in chlamydia among young people aged 16 to 24.
Almost 2,000 youngsters in the county were screened in the past year and 7% tested positive. Health professionals believe that almost 2,600 young people in Dorset could be unaware they have the infection.
"Dorset is an area known for its lively, youthful social life, but recently we have seen an alarming increase in STIs in young people, with chlamydia being the most common," said Barry Alborough, Weymouth Community Hospital's sexual health matron.
Chlamydia is dubbed the silent epidemic and can have serious effects including infertility in women and painful swollen testicles in men.
A large number of cases go undiagnosed because around 50% of infected men and 70% of infected women do not have any symptoms.