MEDICAL ADVISORY: Concerning Syphilis Trends Continue

Issued by: Dr. Jessica Jackman, MD MPH FRCPC FACPM DipABLM, Associate Medical Officer of Health

Date: June 12, 2024

Syphilis Incidence in Niagara

From 2015 to 2019, approximately 53 cases were reported per year in Niagara. In 2020, we began to see a much greater rise in the incidence of syphilis in Niagara, reaching 213 cases in 2022 and 208 cases in 2023.
Included in these numbers from 2023 are three cases of neuro-syphilis and two cases of congenital syphilis.
In 2023 there were 39.3 cases per 100,000 population in Niagara while the province had 36.7 cases per 100,000 population. The incidence of syphilis in Niagara has been higher than the provincial since 2021.

Congenital Syphilis

In 2023, Niagara had 14 cases of syphilis in pregnant individuals; this represents an increase from the 5-year average from 2018-2022 which was 2.6 cases.
The incidence of syphilis among females is increasing. Compared to 2019, the rate of infection among females in 2023 increased from 6.2 per 100,000 population to 30.4 cases per 100,000 population, a fivefold increase.

Epidemiological Shifts

The proportion of syphilis cases among men who have sex with men has decreased but remains high overall.
Syphilis incidence is increasing among individuals who report sex with opposite-sex partners.
Syphilis spread appears to be increasing among individuals who use drugs, are precariously housed, and lack access to primary care.

Health Care Provider Action

Have a high suspicion for syphilis and a low threshold for testing.
- Screen all sexually active persons with new or multiple partners, and/or at the request of the individual. Screening every three to six months is recommended in individuals with multiple partners.
- Given the increasing incidence of syphilis and shift in populations affected, ask all patients about risk factors for acquisition of sexually transmitted infections (STIs), even in the absence of symptoms. Risk factors include a previous STI, new sexual partner(s), multiple or anonymous sexual partners, having sexual partner(s) with a STI, condomless sex, and sex while under the influence of alcohol or drugs.
Individuals being evaluated or treated for a syphilis infection should be tested for chlamydia, gonorrhea, and HIV
Please test all pregnant individuals for syphilis in their first trimester, and again between 28-32 weeks. Repeat testing at delivery should be offered to pregnant individuals with ongoing risk and should be considered for all pregnant individuals regardless of risk.
Please screen all individuals who deliver a stillborn infant after 20 weeks gestation for syphilis
Encourage the use of condoms

Testing and Treatment

To order syphilis testing, write ‘syphilis screen’ in section 3 of the PHO general test requisition
In most cases, first-line treatment for syphilis is Bicillin® L-A (benzathine penicillin G, 2.4 million units), administered by a deep, intramuscular injection in the upper, outer quadrant of the buttock (dorsogluteal) or the ventrogluteal site.
The number of doses required depends on the stage of infection. Please refer to the Canadian STI Guidelines for more information
- Note that short-acting Penicillin G is not a treatment for syphilis
During pregnancy, Bicillin® L-A is the only treatment available
Bicillin® L-A can be ordered from the Sexual Health Centre or by calling 905-688-3817 ext. 7723
For patients with penicillin allergy or other complex scenarios, please refer to the Canadian STI Guidelines or call the Sexual Health Centre

Additional Resources