About The Study

The enhanced syphilis screening among HIV-positive men (ESSAHM) trial assessed the feasibility, usefulness, and cost-effectiveness of improving syphilis screening among HIV-positive men by introducing syphilis screening as a part of regular HIV testing. This trial was the first of its kind in Canada and knowledge gained during the study may be applicable to other sexually transmitted and blood-borne infections in men living with HIV like chlamydia, gonorrhea, and viral hepatitis.

About The Disease

Syphilis is a growing health concern among men who have sex with men (MSM) in Canada and around the world. Bacteria that are transmitted through oral, vaginal, or anal sexual activity cause the infection. Syphillis treatment may be less successful and transmission rates and symptoms of syphilis infection may be more serious in HIV-positive men than in HIV-negative men. Furthermore, both the risk of transmitting and acquiring HIV may be greater for people with syphilis infection. Between 2002 and 2014, 99.9% of HIV-syphilis co-infection in Ontario were in males. No new cases of syphilis among women with HIV have been reported in the province of Ontario.

Study Approach

Four urban HIV clinics in Ontario were involved in the ESSAHM trial. At each clinic, men will receive routine syphilis testing whenever they receive scheduled HIV blood tests. Men attending the clinics could decline syphilis testing or ask for their data not to be used at any point during the trial. The study measured if the introduction of routine testing changes the rates of detection for new, untreated syphilis cases. Other measures of screening coverage and frequency were also be compared.

The study design used in this trial was a stepped wedge cluster-randomized controlled design. The study began with a 6-month baseline period to find out the rate of syphilis detection. The clinics were then randomized to one of four schedules to begin the testing intervention, one after another, each 6 months apart.

If you would like more information on this clinical study, please refer to clinicaltrials.gov.


Main results for CTN 275 were published in 2021. Nearly 4,000 men participated in the study. During the trial, the average number of syphilis tests increased from 0.53 to 2.02 per person per year. There were 217 new cases of syphilis detected, 147 of which were early cases. Overall, there was a 25% increase in detection of new cases of early infectious syphilis. In a separate publication focusing on feasibility, most participants expressed support for implementation of syphilis testing as part of standard HIV care. Participants felt that HIV care clinics are convenient places to be tested for syphilis and that the routine approach de-stigmatized syphilis testing.

Additional Information

If you would like more information on this clinical study, please refer to clinicaltrials.gov.

Principal Investigators

Here’s who is leading this study.

Can’t find what you’re looking for? Email ctninfo@hivnet.ubc.ca.

Dr. Ann Burchell

Co-Leader, Co-infections and Related Conditions Core; Member, Steering Committee

St. Michael’s Hospital

View Bio