Sexually Transmitted Diseases (STDs): Sexually transmitted diseases (STDs) are among the most common infectious diseases in the United States. STDs can be spread through any type of sexual activity involving the sex organs, the anus or mouth, or through contact with blood during sexual activity. Examples of STDs include chancroid, chlamydia, gonorrhea, granuloma inguinale, lymphogranuloma venereum, syphilis, genital herpes, genital warts, hepatitis B, trichomoniasis, pubic lice (crabs), and scabies. Treatment is generally with antibiotics; however, some STDs that go untreated can lead to death.