Canadian Public Health Laboratory Network National Syphilis In-Laboratory Serological Testing Recommendations

Syphilis, caused by the bacterium Treponema pallidum, is a centuries-old sexually transmitted disease that continues to be a significant global health concern. Despite the efficacy of penicillin the disease has seen a resurgence worldwide, including in Canada. In 2022, Canada reported 13,953 cases of infectious syphilis, representing a 109% increase since 2018, and 117 cases of congenital syphilis, a staggering 599% increase. Historically, gay and bisexual men who have sex with men have been predominantly affected; however, recent years have seen a significant rise in female cases, contributing to the increase in congenital syphilis. Syphilis diagnosis is complex, requiring specialized expertise. The Canadian Public Health Laboratory Network last updated its laboratory diagnosis guidelines in 2015. Given the advancements in diagnostic techniques and the pressing need for updated guidance, this document provides an overview of the syphilis-causing pathogen T. pallidum, its transmission, pathogenesis, and clinical manifestations. It also reviews the epidemiology of syphilis, highlighting recent trends in Canada, and discusses current and emerging serological laboratory diagnostic techniques. This updated guidance aims to equip health care professionals with the latest knowledge and recommended testing algorithms to accurately diagnose and manage syphilis, ultimately helping to address the rising rates of this disease and improve public health outcomes in Canada.