They include hepatitis B , hepatitis C , herpes , HIV and HPV . There are some medications available for the symptoms of these infections, but none is curable. Hepatitis B is the only viral STD for which a vaccine is available. Some STDs can be passed through kissing. Most notable is syphilis , which is transmissible through kissing whenever a lesion is present on or in the mouth.
Oral sex does indeed carry a risk of disease transmission.
Many sexually transmitted diseases are fond of mucous membranes, which can allow them to enter the body. Most of the mouth is a mucous membrane, which makes it an area susceptible to infection. Some studies indicate that one factor that increases the risk for oral transmission of STDs is poor dental care. Pregnancy does not offer any protection against STD infection. An STD during pregnancy can adversely affect both the mother and the fetus, so it's very important to be tested for STDs during pregnancy.