The UK Health Security Agency (UKHSA) has confirmed a rise in cases of a sexually transmitted infection (STI) that can lead to dementia if not treated.

The government health agency’s latest update, issued on Wednesday, revealed there were some 9,535 early-stage syphilis diagnoses across England in 2024.

This is a 2% increase from the 9,375 known cases recorded in 2023. The alert adds: “Concerningly, the overall figure for syphilis, including late-stage syphilis or complications from the infection, increased 5% from 12,456 in 2023 to 13,030 in 2024.”

According to NHS guidelines, untreated syphilis can result in “potentially life-threatening complications”. These include heart conditions such as heart failure, organ problems, dementia, and other brain-related issues.

Symptoms of syphilis are often subtle and difficult to spot, and they can evolve over time and may come and go. Key warning signs include painless sores or ulcers on the genitals, mouth, or hands, white or grey wart-like growths, and rashes on the palms or soles.

Some patients may also experience flu-like symptoms, patchy hair loss, and swollen glands. Symptoms can take three weeks or more to appear after infection.

The NHS warns that that in some instances, a person’s symptoms may significantly improve or disappear entirely, but “if you have not been treated the infection is still in your body”. If a person remains infected, they can transmit it to others and are still at risk of more serious health issues in the future.

If you or your sexual partner has symptoms of syphilis, if a sexual partner has disclosed they have syphilis or any other STI, or if you’ve recently had unprotected sex with a new partner, you should see a GP or a sexual health clinic.

The same advice applies if you’ve used a needle for drug use that’s been previously used by someone who may have syphilis, or if you’re pregnant or planning to become pregnant and suspect you may have syphilis.

Syphilis is treatable with antibiotics. If you have syphilis, your current and any recent sexual partners will also need to be tested and treated.