(CBC News) — After Pap tests became less frequent in Canada, testing for chlamydia also decreased, say researchers who recommend that young women should ask their doctors about testing for the sexually transmitted infection.

In May 2012, guidelines from Cancer Care Ontario recommended less frequent Pap tests for routine cervical cancer screening and delaying screening until age 21. The Canadian Task Force on Preventive Health Care suggested similar changes.

Chlamydia is the most commonly diagnosed bacterial sexually transmitted infection worldwide, according to public health authorities.

Most women with chlamydia don’t have symptoms and could unknowingly spread the infection. Left untreated, it can lead to upper genital tract infections or damage to fallopian tubes, leading to infertility as a complication.