Chlamydia and LGV guide: Etiology and epidemiology

Etiology and epidemiology of Chlamydia trachomatis infections (including lymphogranuloma venereum (LGV)).

On this page

• Etiology
• Epidemiology
  • Chlamydia
  • LGV
• References

Etiology

Chlamydia is a bacterial infection caused by C. trachomatis genotypes D to K.

LGV is a bacterial infection caused by C. trachomatis genotypes L1, L2 or L3.

Epidemiology

Chlamydia

Chlamydia is the most common reportable sexually transmitted infection (STI) in Canada. Rates have been increasing steadily since 1997^{Footnote 1}. Chlamydia may be under-detected because the majority of people with an infection are asymptomatic^{Footnote 2Footnote 3} and empiric treatment may be given without laboratory testing.

Males may be under screened due to infrequent health visits^{Footnote 3Footnote 4Footnote 5}. High-risk people may also be under screened.

Sexually active youth and young adults are disproportionately represented in case reports for chlamydia. Between 2010 and 2019, chlamydia infections were most commonly reported in females when compared to males. However, rates are increasing faster in males than females, narrowing the gap in rates between the sexes^{Footnote 6}.

LGV

LGV is relatively rare. Prior to 2004, most Canadian cases were identified in travellers returning from endemic regions of Africa, Southeast Asia, the Caribbean and Latin America^{Footnote 7}. Since 2004, there have been LGV outbreaks in Canada, mainly in gay, bisexual and other men who have sex with men (gbMSM).

National enhanced surveillance of LGV was carried out from 2004-2012. During this time, 104 confirmed and 66 probable cases were reported to the Public Health Agency of Canada (PHAC) by provinces and territories. Confirmed cases were reported from Quebec, Ontario, British Columbia and Alberta; probable cases were reported from these provinces as well as from Nova Scotia.

More information

Local epidemiological information: Consult with your public health unit.

National epidemiological information:

• Notifiable Diseases Online
• Canadian Communicable Disease Report: Chlamydia 2010–2015^{Footnote 1}
• Report on Sexually Transmitted Infection Surveillance in Canada, 2019^{Footnote 6}

Global epidemiological information: World Health Organization Report on global sexually transmitted infection surveillance

References