Syphilis ravages sex workers as more than 10 per cent test positive

The finding suggests the need for regular testing, treatment and consistent use of protection among sex workers and their clients to stop the infections from spreading.

Researchers tested 647 stored blood samples collected between 2013 and 2019 from people enrolled in the Sex Worker Outreach Programme (Swop) in Nairobi.

Most of those sampled were female sex workers (FSW), with a smaller group of men who have sex with men. The results showed that 11.1 per cent had antibodies for syphilis, meaning they had been infected at some point.

Researchers found older sex workers (above 45 years) were more likely to have syphilis compared to younger ones.

“We report a higher seropositive rate than in previous studies in Kenya. As the test does not differentiate between active or prior infection, the seropositivity in the 45-54 and older age groups may reflect the increased amount of time in sex work, leading to more potential syphilis exposures as compared to a younger person,” the researchers said.

Their report is contained in an unpublished paper titled “Seroprevalence of syphilis among sex workers in Nairobi, Kenya.”

Nearly all women accessing antenatal care in Kenya are tested for syphilis and in 2023, fewer than one in ten (0.95 per cent) tested positive.

This places the burden of syphilis on sex workers at probably the highest levels of any subgroup in Kenya.

“The high rate of syphilis positivity in FSWs is particularly concerning, given the possibility of congenital syphilis. For women who become pregnant, this can lead to serious complications, including low birth weight, premature delivery, and stillbirth,” the authors said.

Swop clinics are clinics that provide free services like HIV and STI testing, treatment, and counselling, mainly for sex workers and other people in high-risk activities. They sometimes store blood samples to test for infections later, monitor trends over time, and support research.

The analysis also found a strong link between syphilis and HIV, with infection rates significantly higher among people living with HIV.

Syphilis is a sexually transmitted infection that can be easily treated, but it becomes dangerous when it is missed or ignored. It can damage vital organs such as the brain and heart, and in pregnant women, it can be passed to the baby with severe consequences.

“When untreated, syphilis can eventually lead to several complications, including congenital syphilis in pregnant women, cardiovascular lesions, and dementia,” the study notes.

The risks are even more serious for babies. Infection during pregnancy can lead to miscarriage, stillbirth, premature birth or lifelong illness.

The high rate among female sex workers raises concern because it increases the chances of infection during pregnancy if testing and treatment are missed.

“The high rate of syphilis positivity in FSWs is particularly concerning, given the possibility of congenital syphilis,” the researchers said.

 The authors are from the University of Nairobi, Public Health Agency of Canada, University of Alberta, University of California at Los Angeles, University of Manitoba, Cadham Provincial Laboratory (Canada), the University of Kinshasa, DR Congo, and the National Institute of Biomedical Research.

Kenya has made progress in testing pregnant women, with most screened during antenatal visits. Treatment, however, still lags behind.

The study notes that only 44.3 per cent of women who test positive during antenatal visits receive treatment. This gap leaves many women and their babies at risk.

The findings also show that Kenya’s testing strategy may be missing key populations. Most surveillance focuses on pregnant women, yet infections are clearly higher in groups such as sex workers.

“Surveillance that is conducted is generally done on antenatal populations… this brings the risks of missing syphilis in other high-risk populations,” the study says.

Stigma and discrimination make the situation worse. Many sex workers and sexual minorities face barriers when trying to access healthcare, which means infections can go untreated and continue to spread within communities.