- Calgary doctors noticed a three-fold increase in syphilis among patients with HIV - Syphilis was more common among people with HIV not taking treatment - More than half of cases had no symptoms, highlighting the need for screening Syphilis cases decreased in the 1990s but began to increase in Canada and other high-income countries around the year 2000. This increase has disproportionally affected gay, bisexual and other men who have sex with men (MSM), including those who are HIV positive