It is not absolute. Firstly, whether a history of unhealthy sexual activity can cause Chlamydia trachomatis infection depends largely on whether the sexual partner is a carrier of the pathogenic microorganism. Secondly, the probability of transmission of Chlamydia trachomatis between sexual partners is 45%. However, as there are often no obvious clinical signs of Chlamydia trachomatis infection, then women with a history of unhealthy sexual activity are advised to undergo routine screening for Chlamydia trachomatis to determine if they are infected.