Chlamydia

Indicator #18: Chlamydia Incidence

Indicator 18: Incidence of genital chlamydia among youth age 15–19, expressed as a rate per 100,000, by sex.

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Key Messages

• Chlamydia is the most commonly reported sexually transmitted infection (STI) in BC.^1,2
• Although the health consequences of chlamydia are typically limited, a history of chlamydia infection is an important risk factor for pelvic inflammatory disease, infertility, ectopic pregnancy, and chronic pelvic pain. This is particularly concerning as the incidence of chlamydia is greatest among individuals 15–24 years old.^1,3
• Chlamydia is often asymptomatic. The male rate may reflect symptomatic infection that results in testing and diagnosis. In females, an infection may be undiagnosed until routine testing is done or until complications appear such as pelvic inflammatory disease.^2,3,4 It is believed that females get tested more frequently —as part of a routine pelvic examination and Pap test¹ —than males, because screening programs tend to target females and because males are often treated without diagnostic testing.³ Females also access health services more frequently than males in general.⁴
• There is evidence that chlamydia infections are associated with poorer socio-economic status, reflecting social vulnerabilities and disparities that require consideration of the social determinants of health and increasing equitable reach of prevention strategies, testing, and treatment.^5,6
• Many studies have shown that other STIs often coexist in young people with chlamydia and are often amplified in certain risk groups. Since chlamydia is the most prevalent STI in jurisdictions such as the US (1997),³ Canada, and BC (2014),¹ chlamydia diagnoses may allow health care practitioners to identify youth at-risk for a number of other things and identify a more vulnerable population for targeted health interventions. ⁷
• The incidence of chlamydia may reflect risky sexual activity, such as not using condoms (condom use is an effective intervention to prevent acquisition of chlamydia. Thus, monitoring trends in chlamydia incidence among youth could be a proxy for sexual knowledge, skills, practices, and attitudes, particularly around negotiating condom use.^2,8
• The chlamydia incidence rate when calculated as a percentage of the total youth population is a significant underrepresentation of the rate among those who are sexually active.⁹
• As shown in Figure 18.1, there are substantial differences between sexes in chlamydia rates, with the female rate being much higher than the male rate.
• Figures 18.2 and 18.3 show that there are also key geographic differences in incidence of chlamydia across BC.

Figure Notes and Sources