Eye syphilis is on the rise in the United States, health officials warn.
More than 200 people across 20 states were diagnosed with the sexually-transmitted disease in their eyes between 2014 and 2016, according to data from the Centers for Disease Control and Prevention.
Ocular syphilis, which can cause blindness and blurry vision, develops out of a syphilis infection in the spinal cord, which spreads to the eye.
While it was once rare but rates have been steadily climbing in America in recent years.
More than 200 people across 20 states were diagnosed with the sexually-transmitted disease in their eyes between 2014 and 2016, CDC data show (file image)
According to the CDC, ocular syphilis can involve any part of the eye, but it typically causes inflammation of the middle layer of the eye.
It can blur vision and ultimately lead to vision loss, and can even travel up into the brain.
A chronic bacterial disease, syphilis can be contracted by other means but is typically a sexually-transmitted disease.
In very rare cases, it can be spread through prolonged kissing, as well as the more common routes of transmission: vaginal, anal and oral sex.
It comes from the bacteria Treponema pallidum.
Syphilis is notoriously difficult to diagnose since its symptoms are similar to other conditions – a runny nose and soar throat. Sufferers develop sores, though these can often go ignored.
However, rates are rocketing across the United States.
While the rate of all sexually-transmitted diseases has gone up, the biggest increase was seen in cases of congenital syphilis, which went up 27.6 percent between 2015 and 2016.
The rate of primary and secondary syphilis infections went up 17.6 percent since 2015.
In the early stages, patients can receive an injection of Benzathine penicillin G. This will not undo the internal damage but will eliminate the infection.
For those with latent syphilis – and are unsure how long they had it – doctors recommend having three doses of the penicillin injection, seven days apart from each other.