Nearly two-thirds of sexually active young women are not getting tested for chlamydia, according to a new Centers for Disease Control and Prevention survey. This is an extremely alarming fact and means that a large percentage of the delicate half of the population does not suspect that it may be infected, experts believe. Nearly 5% of girls at the age of 19 and more than 1% of those at the age of 15 have the chlamydial infection without suspecting it. This is due to its asymptomatic course. In the absence of treatment, chlamydia can cause pelvic inflammatory disease or infertility in 10%-15% of women. Experts advise that every sexually active woman should be tested for chlamydia annually, especially if she does not have a permanent partner. Chlamydial infection is caused by an intracellular parasite called Chlamydia trachomatis. It is sexually transmitted and affects both men and women. In addition to the genitals, it enters the eyes, joints, liver and lungs. The incubation period is 7-14 days. Treatment is difficult and in some cases prolonged. Both sexual partners are treated.