Sexually transmitted diseases (STDs) - also known as sexually transmissible diseases, sexually transmitted infections (STIs) or (infrequently) venereal diseases (VD) or social disease - are diseases or infections that have a significant probability of transmission between humans by means of sexual contact, vaginal intercourse, oral sex, and/or anal sex.
Classification and terminology
Until the 1990s, such afflictions were commonly known as venereal diseases: Veneris is the Latin genitive (possessive) form of the name Venus, the Roman goddess of love. More recently, public health officials introduced newer terms such as sexually transmitted disease in efforts to improve the clarity of their warnings to the public.
The term sexually transmitted disease remains in common use; however, clinicians are increasingly using the term sexually transmitted infection and sometimes distinguish the two. According to http://www.etharc.org:
"Sometimes the terms STI and STD are used interchangeably. This can be confusing and not always accurate, so it helps first to understand the difference between infection and disease. Infection simply means that a germ ? virus, bacteria, or parasite ? that can cause disease or sickness is present inside a person?s body. An infected person does not necessarily have any symptoms or signs that the virus or bacteria is actually hurting their body (they do not necessarily feel sick). A disease means that the infection is actually causing the infected person to feel sick, or to notice something is wrong. For this reason, the term STI - which refers to infection with any germ that can cause an STD, even if the infected person has no symptoms - is a much broader term than STD."
The distinction being made, however, is closer to that between a colonization and an infection, rather than between an infection and a disease.
Specifically, the term STD refers only to infections that are causing symptoms or problems. Because most of the time people do not know that they are infected with an STD until they start showing symptoms of disease, most people use the term STD, even though the term STI is also appropriate in many cases.
Moreover, the term sexually transmissible disease is sometimes used since it is less restrictive in consideration of other factors or means of transmission. For instance, meningitis is transmissible by means of sexual contact but is not labeled as an STI because sexual contact is not the primary vector for the pathogens that cause meningitis. This discrepancy is addressed by the probability of infection by means other than sexual contact. In general, an STI is an infection that has a negligible probability of transmission by means other than sexual contact, but has a realistic means of transmission by sexual contact (more sophisticated means?blood transfusion, sharing of hypodermic needles?are not taken into account). Thus, one may presume that, if a person is infected with an STI (e.g., chlamydia, gonorrhea, genital herpes), it was transmitted to him/her by means of sexual contact.
Types and their pathogenic causes
Most of the diseases on this list are most commonly transmitted sexually. Some of the diseases on this list are commonly transmitted in other ways besides sexually; for example, HIV/AIDS is also commonly transmitted through the sharing of infected needles by drug users, and candidiasis, while it can be sexually transmitted, while SARS, excluded from the list, which can be spread through casual contact such as coughing and sneezing, is very often not associated with sexual activity.
* Chancroid (Haemophillius ducreyi)
* Chlamydia infection (Chlamydia trachomatis)
* Donovanosis (Granuloma inguinale or Calymmatobacterium granulomatis)
* Gonorrhea (Neisseria gonorrhoeae)
* Lymphogranuloma venereum (LGV) (Chlamydia trachomatis serotypes L1, L2, L3. See Chlamydia)
* Non-gonococcal urethritis (NGU) (Ureaplasma urealyticum or Mycoplasma hominis)
* Syphilis (Treponema pallidum)
* Hepatitis B. Note that Hepatitis A and Hepatitis E are transmitted via the fæcal-oral route, not sexually; Hepatitis C is rarely sexually transmittable, and the route of transmission of Hepatitis D is uncertain, but may include sexual transmission.
* Herpes /HSV (Herpes simplex virus)
* Human Immunodeficiency Virus (HIV/AIDS)
* Human papillomavirus (HPV)
o Certain strains of HPV cause genital warts
o Certain strains of HPV cause cervical dysphasias which can lead to cervical cancer
* Molluscum (MC)
* Pubic lice a.k.a "crabs" (Phthirius pubis)
* Scabies (Sarcoptes scabiei)
* Candidiasis (thrush) (Candida albicans) is not strictly an STD but can be transmitted through sexual contact
* Trichomoniasis (Trichomonas vaginalis)