U of M researchers recommend better chlamydia screening after analysis of Prairie infection rates

Researchers at the University of Manitoba are recommending improved chlamydia screening and wider data collection after a study analyzed significant spikes in reported infection rates.

Manitoba, Saskatchewan and Alberta consistently reported infection rates 1.5 to two times higher than the national average between 1991 and 2022, the study found.

“This finding is signally significant insofar as the three provinces account for only 18.2 per cent of Canada’s total population,” the researchers said in the journal Infectious Diseases Now.

The study — led by Dr. Zulma Rueda, a U of M associate professor and Canada Research Chair in sexually transmitted infection resistance and control — looked at the evolution of incidence rates in the Prairie provinces, using data from publicly available reports.

Researchers said Manitoba had a rate of 410.2 cases per 100,000 people in 1991, when the national average was 164 cases.

Manitoba’s peak during the 30-year period was 604.5 cases per 100,000 in 2019 against a national average of 370.8 cases.

The province’s per capita rate in 2025 was 463.1 cases amid a downward trend, a recent Manitoba government surveillance report said.

Females accounted for 60-65 per cent of reported infections in the three Prairie provinces from 1992 to 2022. The 15-29 age group was a severely affected group.

The study identified a significant spike in infections among people in their 30s — a group that is outside Canada’s recommended age for increased screening.

Data on race or ethnicity was not consistently reported in Manitoba, but findings indicated Indigenous Peoples have a “disproportionately high burden” of chlamydia, researchers found.

The study recommended increased screening of people in their 30s, and equity-informed surveillance to sort data by sex, age, gender, sexual orientation, race/ethnicity, housing status and other indicators to help identify and tailor public health strategies toward the most affected groups.

Chlamydia rates in Manitoba have been stable in more recent years, while infections continue to be highest among people in their 20s and 30s, a provincial spokesperson said Thursday.

The spokesperson said Manitoba Health collaborates with health-care providers, regional public health teams and community organizations to increase awareness about sexually transmitted and blood-borne infections, and the importance of getting tested and treated, if required.

A Health Canada spokesperson said the department needed more time to respond to the study’s findings and recommendations.

A nationwide increase in chlamydia infections could be partially explained by improvements in testing, the researchers said.

Females could have higher rates because of biological differences, they are generally more likely than males to seek care, and they may be more likely to be screened opportunistically (during testing for cervical cancer or pregnancy, for example).

Differences in rates by province could be partly attributed to factors such as socioeconomic and demographic characteristics, and varied screening, testing and reporting practices.

The true number of chlamydia cases is likely higher due to asymptomatic, undiagnosed or unreported infections.

chris.kitching@freepress.mb.ca