Chlamydia and lymphogranuloma venereum in Canada: 2003-2012 Summary Report

Chlamydia continues to be the most commonly reported sexually transmitted infection in Canada. Lymphogranuloma venereum (LGV), caused by certain serovars of Chlamydia trachomatis, is becoming established in some populations in a number of Western countries.

To identify trends in reported cases of chlamydia and LGV in Canada from January 1, 2003 to December 31, 2012.

Notifiable disease data on chlamydia were submitted to the Public Health Agency of Canada by provincial and territorial epidemiological units and summarized at the national level by age and sex. Confirmatory testing for suspected LGV cases and serovar subtyping were performed by the National Microbiology Laboratory (NML). Where possible, provincial/territorial health authorities use a standardized national case report form to collect enhanced epidemiological data on each case and to submit the data to the Agency.

Rates of reported cases of chlamydia increased by 57.6%, from 189.6 to 298.7 per 100,000 between 2003 and 2012. The rate of reported cases of chlamydia among females (383.5 per 100,000) was almost twice as high as that among males (212.0 per 100,000), although the highest relative rate increase occurred among males. In both males and females, the rates of chlamydia were highest in those aged 20 to 24 years. From 2004 to 2012, 170 cases of LGV were reported to the Agency by provincial health authorities (including 104 confirmed and 66 probable cases). In 2012, case reports were received on 12 confirmed and probable cases, compared to 38 laboratory-positive cases confirmed by the NML.

In Canada, as in many countries, chlamydia rates have markedly increased over the last 10 years, in part due to improved diagnosis through nucleic acid amplification (NAAT) testing. Consistent with trends in Europe and other countries, LGV is emerging in Canada among men who have sex with men (MSM).