Ear, nose and throat specialists in Spain are urging doctors to consider syphilis as a possible cause of hearing loss, as infections remain at high levels. The disease can affect hearing in around one in every 200 cases, according to a US study, and may cause damage even when other signs of infection are absent or have gone unnoticed.

Cases presented at the Spanish Society of Otolaryngology and Head and Neck Surgery’s 77th national congress in October included a patient whose syphilis had not initially been recognized. The patient later developed rapid hearing loss. Antibiotic treatment cleared other symptoms, but the hearing damage persisted and ultimately required cochlear implants.

Syphilis-related hearing problems can begin suddenly or worsen over time, affect one or both ears, and occur alongside tinnitus, vertigo or instability. These symptoms do not usually prompt doctors to suspect syphilis, says Montserrat Asensi Díaz, an otolaryngologist at Madrid’s Gregorio Marañón Hospital. She describes the main diagnostic challenge as recognizing the possibility of otosyphilis.

Spain recorded 11,879 syphilis cases in 2025, compared with 11,964 in 2024, according to the latest report from the Carlos III Health Institute. The 0.7% decrease followed a decade of sharp increases and left case numbers close to the highest level in the series, which began in 1995. Victoria Hernando, of the National Epidemiology Centre’s surveillance unit for HIV, sexually transmitted infections and hepatitis, said cases had stabilized but remained high.

The number of infections that lead to hearing complications in Spain is unknown. National surveillance tracks early syphilis but does not monitor the development of auditory complications. A US Centers for Disease Control and Prevention study found ear-related symptoms in 0.4% of 41,187 syphilis cases; its authors cautioned that underreporting may have missed some cases.

Hearing loss can occur at any stage of syphilis, including early stages, and may be the first sign of an infection. Asensi says evaluation of sudden hearing loss can include a medical history, examination, hearing tests and blood tests for syphilis, alongside checks for other causes. Treatment, generally intravenous penicillin, should begin as early as possible. If damage is irreversible, antibiotics may clear the infection without restoring hearing.

In a review conducted by Asensi and her team, 22 of 44 patients recovered their hearing fully after treatment, while 12 recovered partially. Hearing aids may help when hearing loss remains; cochlear implants can be considered if they are not sufficient.

Hernando points to condom promotion, campaigns for populations at greater risk, healthcare training and easier access to testing as important prevention measures. Asensi advises people with hearing loss, particularly sudden loss, to seek medical attention promptly and urges clinicians to consider syphilis as a possible cause.

Sources: El País Sociedad.