What it is: Syphilis is a bacterial STD that gets into the bloodstream and causes canker sores and rashes.

How you get it: Oral, anal or vaginal sex. Possibly kissing, since sores can appear on the mouth.

Symptoms: Appear in several stages and need to be paid attention to because the disease must be halted as soon as possible. First a sore appears where contact was made; the sore becomes oozy and eventually dries up. (The oozy stage is the most infectious.)

Untreated, the bacteria can live on and then appear as a rash, fever and headache. If that clears up on its own, the disease can become latent, and the person becomes a carrier.

Prevention: Barrier methods reduce risk. Of course, people should make sure they are cured before resuming sexual activity with anyone.

Treatment: Antibiotics.

Long-term Implications: Untreated syphilis can lead to degeneration of vital organs, brain damage and death.