An Overview of Syphilis and Its Transmission

Syphilis bacteria, illustration

Syphilis is one of the better-known sexually transmitted diseases. You might even say that it is infamous. One of the biggest scientific scandals of the 20th century stemmed from a study of this sexually transmitted disease. The controversies over the handling of the Tuskegee syphilis study have affected the way research has been done ever since.

Syphilis is considered to be a genital ulcer disease.

The chancres, or sores, that are the first symptoms of syphilis provide an easy route of entry into the body for other viruses. In particular, syphilis can significantly increase the risk of acquiring HIV.

All genital ulcer diseases put a person at an increased risk of HIV/AIDS. Therefore, it is extremely important for you and your sexual partners to be tested and treated for syphilis if you have been exposed to the disease. Although throughout the 1990s the rates of syphilis had been declining, in recent years many cities have seen a surge in the number of cases. Some of this increase is thought to be due to transmission during oral sex among men who have sex with men.


Syphilis is spread by direct contact with a syphilis sore. This usually occurs during oral, vaginal, or anal sex. In the early stages, syphilis just appears as a painless rash. The sores it causes are easy to miss—particularly when they're inside the mouth.

If left untreated, syphilis can go on to cause disease in other organs of the body. This includes the central nervous system. Syphilis infections of the brain and spinal cord are known as neurosyphilis.

Syphilis can also be transmitted from mother to infant during pregnancy. Congenital syphilis can be a very dangerous condition.

It can lead to serious disability or even death. This is why it is generally recommended that pregnant women be tested for syphilis. Even though the disease has become rare, every congenital case is a serious problem.


It is said that sex has driven people mad.

This is not true in general, of course. Most of the time sex just makes people feel good. Sometimes it helps them create the next generation. However, sex can be quite stressful. Additionally, in certain specific cases, the madness caused by sex is literal. Infections acquired through sex can actually cause damage to the brain. One example of this is what happens when a person suffers from an untreated case of syphilis.

Left untreated, genital syphilis cases can progress and become neurosyphilis. Neurosyphilis does not always cause symptoms. However, it can cause blindness, personality changes, dementia or even death. Some historians have attributed the madness of men such as Hitler, Neitzche, and Jack the Ripper to syphilis. That's plausible speculation, but it is just speculation. There has been very little data to support such theories of the role of syphilis in history. That said, syphilis certainly can have significant effects on individual lives.

Congenital Syphilis

Syphilis during pregnancy is a serious medical concern. This is because of the risk of the fetus becoming infected. Congenital syphilis occurs when a mother who has syphilis during pregnancy transmits the disease to her growing fetus.

Congenital syphilis can cause neurological problems such as seizures and developmental delays. It can also cause other problems with the kidneys, spleen, bones, facial features and joints. More worrisome still is the fact that untreated syphilis during pregnancy can lead to stillbirth or early infant death. These serious outcomes may occur in up to 40 percent of affected infants.

Congenital syphilis can be somewhat difficult to diagnose. The standard diagnosis is based on a blood test that looks for antibodies to the syphilis bacterium. However, those antibodies can be transmitted from the mother to the child. Therefore, when congenital syphilis is suspected, doctors must use a somewhat complicated protocol to try to determine whether or not a child is actually infected. This may require repeated testing and judgment calls. Treatment of infants with congenital syphilis is with various forms of penicillin. The specific regimen will depend on both maternal and infant test results and specific signs of disease.

Because the complications of congenital syphilis can be so severe, the CDC recommends that all women be screened for syphilis at their first prenatal visit. It is also suggested that women at high risk of congenital syphilis be screened again at 28 weeks. Tests are very low risk, but missing a case of syphilis during pregnancy can have a very high cost.

If a woman tests positive for syphilis during pregnancy, she should also talk to her sexual partners. They should also be tested and treated to avoid the possibility of reinfection.


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Workowski KA, Bolan GA; Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines, 2015. MMWR Recomm Rep. 2015 Jun 5;64(RR-03):1-137. Erratum in: MMWR Recomm Rep. 2015 Aug 28;64(33):924. 

Kaplan RM. Syphilis, sex and psychiatry, 1789-1925: Part 2. Australas Psychiatry. 2010 Feb;18(1):22-7. doi: 10.3109/10398560903295717.

Retief FP, Wessels A. Did Adolf Hitler have syphilis? S Afr Med J. 2005 Oct;95(10):750, 752, 754, 756.