A new study into recent cases of ocular syphilis warns increasing numbers of people are at risk of permanent damage to their vision.

Researchers from the University of Sao Paulo in Brazil and Flinders University, led by Matthew Flinders Distinguished Professor of Ophthalmology Justine Smith, analysed cases at four medical centres in Brazil over two and a half years.

The number of cases of ocular syphilis had increased more than eight times in this period, compared to the past decade

The study identified 127 patients with 87 of these suffering inflammations in both eyes. Exams revealed that some patients had suffered structural and functional complications inside the eye, such as retinal detachment.

Professor Smith, from Flinders University’s College of Medicine and Public Health, says the disease can lead to blindness if not treated in a timely manner.

Professor Smith says the findings in Brazil are a reflection of the re-emergence of this infectious disease around the world.

“When ocular syphilis goes untreated or is treated late, the damage done to internal components inside the eye may be permanent,” says Professor Smith.

“However symptoms often can be reversed entirely with early treatment.”

The most common symptoms is blurry vision but because many signs of ocular syphilis can mimic a variety of other illnesses, the diagnosis can often be overlooked.

Ocular syphilis is a sexually transmitted infection (STI) caused by the bacteria Treponema pallidum.

Co-author Professor João Marcello Furtado from the University of Sao Paulo, says general practitioners should refer eye complaints to ophthalmologists whenever they diagnose a case of syphilis.

“There is no longer a stigma associated with syphilis. Anyone can be exposed and infected, so early detection is increasingly important,” he says.

The majority of cases identified around the world have been attributed to high-risk sexual practices, an increase in global travel, and the effects of anti-HIV medications on the immune system.

“The 1990s and 2000s indicated that ocular syphilis was a rare diagnosis, accounting for less than 2% of all cases of uveitis [inflammation inside the eye].

“More recent reports describe cohorts of up to 85 patients with ocular syphilis in the Americas, countries in Europe, and parts of Australasia which shows it’s not only a problem in Brazil,” Professor Furtado says.

Professor Smith says more than half of the patients studied lost vision to below driving level.

“Our most important observation is the role of testing in making a timely diagnosis of ocular syphilis, which should limit the risk of vision loss,” Professor Smith says.

“Patients didn’t present to clinics for treatment until they had a problem for some months, but it is not completely the fault of the patient.

“Doctors are no longer accustomed to seeing syphilis these days, so it may not be picked up for an extended period of time, during which patients may develop eye complications.”

Clinical Manifestations and Ophthalmic Outcomes of Ocular Syphilis at a Time of Re-Emergence of the Systemic Infection, by João M. Furtado, Tiago E. Arantes, Heloisa Nascimento, Daniel V. Vasconcelos-Santos, Natalia Nogueira, Rafael de Pinho Queiroz, Luana P. Brandão, Thaís Bastos, Ricardo Martinelli, Rodrigo C. Santana, Cristina Muccioli, Rubens Belfort Jr and Justine R. Smith has been published in Nature journal Scientific Reports.