There are two types of syphilis, both caused by a bacterium called Treponema pallidum. The bacterium is a sphirochete, which means it has a spiral shape. This shape allows it to corkscrew its way through a patient's mucous membranes and infect them. The bacteria can move remarkably fast and can infect nearly every organ in the body within days.
The congenital form of syphilis is caused when a baby is born to a mother who has syphilis. The bacterium is passed from the mother's bloodstream through the placenta and onto the baby. Congenital syphilis is also a major reason for stillbirths in developing parts of the world.
Contagious syphilis is caused by sexual contact. A person who has first or second stage syphilis passes the disease on to another. This can happen to people of all ages. In the first stages of syphilis, a chancre, or red sore can appear on the person's mouth, around the anus, or on the genitals. If the chancre is around the anal-genital region, the person might not be able to see it.
The second stage of contagious syphilis, which is the most contagious stage, begins six weeks after the chancre appears. The person has enlarged lymph glands, headache, and a rash on the skin and the mucous membranes. Sometimes, the person has a fever. He or she can have contagious syphilis for as long as two years.
The third stage of the disease is considered noncontagious. The symptoms include both mental and physical deterioration that can lead to tissue destruction and even death if they're not treated.
In 1998, it was announced that the genome of Treponema pallidum had been sequenced. It's hoped that this will lead to a better understanding of how the bacterium causes syphilis and related diseases. Even though antibiotics work well against Treponema pallidum, there's still no specific vaccine that targets the bacteria. The bacterium has proven to be rather primitive, and its genome is so small that it has very few proteins on its surface that can be attacked by a vaccine. Despite this, scientists are continuing to study the bacteria intensively.
Fortunately, syphilis can now be easily treated with penicillin and other antibiotics. The other good news about syphilis treatment is that the bacterium doesn't show signs of becoming resistant to antibiotics.