Syphilis has been called many names since the first record of it in the 1490s, most of them uncomplimentary – "the French disease", "the Neapolitan disease", "the Polish disease".
One however has stuck: "the great imitator". Syphilis is a master at mimicking other infections and early symptoms are easy to miss. Left untreated, the consequences can be serious.
Tushar, a 33-year-old project officer in Amsterdam, has had syphilis twice. He remembers first receiving the news via WhatsApp from his sexual partner at the time.
"They were really upset," he says. "They blamed me which wasn't possible because of the window period. It felt strange to be accused and it took some time to de-escalate." Tushar got tested and treated that week. "People mistakenly think syphilis is something that cannot be cured. People don't understand what it means to still have syphilis antibodies and not have the infection."
In April, the US released its latest data on sexually transmitted infections (STI). Cases of syphilis saw the largest increase, with cases surging 32% between 2020 and 2021 to reach the highest number of reported incidences in 70 years. The epidemic is also showing no signs of slowing, the Centres for Disease Control and Prevention (CDC) warned. And it has pointed to some "alarming" new trends driving this sudden spike in the disease.
Congenital syphilis – where a mother passes the infection to her child during pregnancy, often after contracting it from their partner – has risen particularly sharply, with cases soaring in the US by 32% between 2020-2021. The disease can cause stillbirths, infant deaths and life-long health problems.
It has left many health experts reeling.
"Fifteen or 20 years ago we thought we were on the verge of eliminating syphilis," says Leandro Mena, director of the CDC's division of sexually transmitted disease prevention. "There is no doubt we are seeing increasing rates of syphilis, rates we have not seen in the past 20 years or so."
And it is not something just happening in the US. There were 7.1 million new cases of syphilis globally in 2020 according to World Health Organization data. In 2022, the UK saw syphilis cases reach their highest level since 1948.
The rise in cases is something sexual health practitioners working on the frontline have grown familiar with.
"When I first started sexual health nursing in 2005, it was quite rare to see primary syphilis, even in a city centre clinic," says Jodie Crossman, co-chair of the STI Foundation in the UK, where syphilis rates jumped 8.4% between 2020 and 2021. "Now most city-based clinics will see at least two or three patients per day attending for treatment."
The infection is caused by a bacterium called Treponema pallidum and symptoms are divided into four stages. The earliest is characterised by a painless sore at the site of contact or a rash. An intramuscular dose of penicillin is considered to be the most effective way of treating the infection. Left untreated, however, syphilis can lead to long-term neurological and cardiovascular diseases.
Watching the epidemic unfold in the US from across the border in Canada is Isaac Bogoch, an infectious diseases clinician and researcher at the University of Toronto.
"This is the trend that's being seen in multiple countries around the world," he says. "It's very concerning because generally, syphilis is very easy to treat, and treatment is widely available. So, a lot of this is reflective of a breakdown in public healthcare."
Canada saw an increase of 389% for infectious syphilis, significantly higher than other STIs, between 2011 and 2019.
In recent decades, most cases of syphilis are among gay, bisexual and other men who have sex with men. Some parts of the world, however, are seeing a decrease in syphilis cases among men. Rates of infectious syphilis in Canada decreased among males, for example. But at the same time there has been a rise in rates among women not just in Canada but globally, which has led to higher rates of congenital syphilis in many parts of the world. Across the Americas as a whole there were 30,000 cases of mother-to-child transmissions of syphilis in 2021, a figure that health officials describe as "unacceptably high".
The transmission of syphilis during pregnancy to an unborn child can have devastating consequences including miscarriage, stillbirth, premature births, low birth weights and the death of a baby shortly after birth.
In the US, congenital syphilis rates are soaring. They were 3.5 times higher in 2020 compared to 2016 and increased again in 2021, resulting in 220 stillbirths and infant deaths. And the national figures appear to hide some exceptionally dramatic rises in some parts of the country – doctors in Mississippi have reported congenital syphilis cases soaring by 900% over the past five years.
The highest numbers are seen among Black American and Hispanic women.
...
Among the disparities that might be driving this problem are access to STI testing sites, ongoing stigma around syphilis and possible language barriers. One study in the Brazil found a link between black women who had low levels of schooling and higher rates of congenital syphilis. In many cases women struggle to access suitable prenatal care that would provide screening for syphilis.
Another study in Kern County, California – which in 2018 made up 17% of the state's congenital syphilis cases despite representing only 2.3% of the state’s population – identified the role of immigration status, medical insurance status and sexual or domestic violence in pregnant women seeking prenatal care. Half of the pregnant or post-partum women interviewed identified as being of Hispanic, Latino or Spanish origin.
A 2020 study of syphilis in Australia saw figures increase by nearly 90% from recorded rates in 2015. Some 4,000 cases of syphilis were identified amongst the Aboriginal and Torres Strait Islander communities which make up just 3.8% of the total Australian population. And whilst a national test and treat response plan came into play to stabilise the epidemic, experts say reducing levels to pre-outbreak figures requires a much higher level of community wide testing. Again, there have been particular problems with expectant mothers accessing prenatal screening for syphilis in parts of the country.