Chlamydia and LGV guide: Etiology and epidemiology

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}. Adolescents and young adults are disproportionately represented in national case reports for chlamydia, with the highest rates among 20- to 24-year olds for both males and females.^{Footnote 2} Between 2012 and 2019, national rates of chlamydia increased by 10% for females and 45% for males. In 2020 and 2021, reported rates of chlamydia were below pre-pandemic levels with the COVID-19 pandemic reducing the demand for and access to services related to sexually transmitted and blood-borne infections (STBBI), including testing ^{Footnote 3}.

Chlamydia may be under-detected because the majority of people with an infection are asymptomatic^{Footnote 4Footnote 5} and empiric treatment may be given without laboratory testing.

Males may be under screened due to infrequent health visits^{Footnote 5 Footnote 6 Footnote 7} and people at higher risk for chlamydia infections may also be under screened.

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 8}. Since 2004, there have been LGV outbreaks in Canada, mainly among 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
• Report on Sexually Transmitted Infection Surveillance in Canada, 2019

Global epidemiological information:

• Report on global sexually transmitted infection surveillance, 2018

References