The silent sex menace

Chlamydia is known as the 'silent' infection because it often remains symptomless. It is passed on through unprotected sex.

One common health complication caused by it is pelvic inflammatory disease - an agonising infection of the fallopian tubes. The condition can be cleared by antibiotics, but damage may include scarring to the delicate lining of the tubes which can become blocked, leading to infertility.

A further side effect is an increased likelihood of ectopic pregnancy, in which the foetus implants in the fallopian tube outside the womb.

The tube may rupture leading to potentially fatal bleeding. Often, all doctors can do is remove the damaged tube, further harming the chances of conception.