TD stands for , also called sexually transmitted infections (STIs). STDs are infections that spread from person to person through sexual activity, including anal, vaginal, or oral sex. STDs are caused by bacteria, parasites, and viruses.
Many health care providers use the term “infection” instead of “disease”, because a person with an infection may have no symptoms but still require treatment. When untreated, an STI can become a disease.
HIV is a sexually transmitted infection, but it can progress to a disease called when HIV infection is untreated with HIV medicines. Other examples of STDs are , , , and .