Alberta’s decision to declare a provincewide outbreak of syphilis is the latest sign the sexually transmitted infection has reached near-record levels as it spreads across Canada.

However, experts say it’s unclear why a contagion that seemed close to eradication a few decades ago is now thriving.

Dr. Deena Hinshaw, Alberta’s chief medical officer, said on Tuesday that syphilis rates in the province have reached levels not seen since 1948. The 1,536 cases reported in 2018 were a tenfold increase over the 161 reported in 2014, and the rate of increase is only getting worse, she warned.

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Syphilis rates have been increasing across Canada for the past decade, along with higher rates of other sexually transmitted infections, but Alberta’s numbers indicating skyrocketing infections in 2018 could be a sign of the problem developing in other provinces, experts warn. In Manitoba, for instance, syphilis cases hit a record high in 2018. Thin public reporting on syphilis, with a number of provinces not reporting new data since 2016, has made it difficult to get a sense of the national scope of the problem.

“This is a trend that we are seeing across Canada and around the world; syphilis cases are sharply rising in many jurisdictions, not just our own,” Dr. Hinshaw told reporters in Edmonton as she declared the provincewide outbreak. She warned that anyone in the province who is sexually active is at risk.

A number of theories exist for why the infection has spread so rapidly, including risks to marginalized communities due to substance abuse highlighted by the continuing opioid crisis, the spread of smartphone apps that facilitate anonymous meetups and declining condom use among young Canadians.

Data in recent years has shown rates of gonorrhea, chlamydia and syphilis increasing across Canada, said Alex McKay at the Sex Information and Education Council of Canada.

“Concern about HIV has dissipated somewhat within the population, so the motivation to use condoms as a regular habit has been declining. There’s a real need for a wake-up call for Canadians about the need to use protection against all STIs and syphilis in particular,” he said.

Two groups in particular that have faced higher risks of contracting syphilis are Indigenous communities and gay men, largely because they have smaller sexual networks, said Nathan Lachowsky at the University of Victoria’s School of Public Health and Social Policy.

While an effective treatment exists, there’s a need to increase screening, especially among expectant mothers, he added. One of the problems with detecting syphilis is that it requires a blood test, which is not always offered when health facilities are screening for sexually transmitted infections.

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“Syphilis is one of those infections where we already have highly effective treatment, so that’s a relief for people but they are still surprised that this is back," he said. “This was a historical infection, however there can be significant problems if it goes untreated.”

The rate of syphilis infection in Alberta has soared in the province’s north, where the rate of infection per 100,000 people increased from near the national average of about 10 in 2017 to 43.54 the following year. In Edmonton, the rate went from 17.59 to 69.98. In Calgary, the rate increased from 11.83 to 12.47 in 2018.

In Ontario, a rate of 11 cases per 100,000 people was detected in 2017, the latest year for which statistics are available.

The data coming out of Alberta is a sign of something new and troubling after a decade of increases, said James Blanchard, an epidemiologist and public health specialist at the University of Manitoba.

“Something categorically different is happening and that’s why we have an outbreak. It’s beyond the types of increases we were seeing over the past decade or so, this is something new,” he said, before adding it may be a sign that the public health system is failing marginalized groups in the province’s north.

“A lot more has to be done systematically to study this. But usually when syphilis rises like this, now amongst women and heterosexual populations in Canada, it indicates that there has been a major change in social and sexual networks," he said. “There’s been a change in how people interact with each other.”

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