Sexually transmitted diseases
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 discrepency 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.
Many STIs are (more easily) transmitted through the mucous membranes of the penis, vulva, and (less often) the mouth. The visible membrane covering the head of the penis is a mucous membrane, though, for those who are circumcised it is usually dry and it produces no mucus (similar to the lips of the mouth). Mucous membranes differ from skin in that they allow certain pathogens (viruses or bacteria) into the body (more easily).
This is one reason that the probability of transmitting many infections is far higher from sex than by more casual means of transmission, such as non-sexual contact—touching, sharing cutlery, shaking hands, but it is not the only reason. Although mucous membranes exist in the mouth as in the genitals, many STIs seem to be easier to transmit through oral sex than through deep kissing. According to this chart [], many infections that are easily transmitted from the mouth to the genitals or from the genitals to the mouth, are much harder to transmit from one mouth to another. With HIV, genital fluids happen to contain much more of the pathogen than saliva. Some infections labeled as STIs can be transmitted by direct skin contact. Herpes simplex and HPV are both examples.
Depending on the STD, a person may or may not still be able to spread the infection if no signs of disease are present. For example, a person is much more likely to spread herpes infection when blisters are present (STD) than when they are absent (STI). However, a person can spread HIV infection (STI) at any time, even if he/she has not developed symptoms of AIDS (STD).
All sexual behaviors that involve contact with another person or the bodily fluids of another person should be considered to contain some risk of transmission of sexually transmitted diseases. Most attention has focused on controlling HIV, which causes AIDS, but each STD presents a different situation.
As may be noted from the name, sexually transmitted diseases are transmitted from one person to another by certain sexual activities rather than being actually caused by those sexual activities. Bacteria, fungi, protozoa or viruses are still the causative agents. It is not possible to catch any sexually transmitted disease from a sexual activity with a person who is not carrying a disease; conversely, a person who has an STD got it from contact (sexual or otherwise) with someone who had it, or his/her bodily fluids.
Although the likelihood of transmitting various diseases by various sexual activities varies a great deal, in general, all sexual activities between two (or more) people should be considered as being a two-way route for the transmission of STDs (i.e. "giving" or "receiving" are both risky).
Healthcare professionals suggest safer sex, such as the use of condoms, as the most reliable way of decreasing the risk of contracting sexually transmitted diseases during sexual activity, but safer sex should by no means be considered an absolute safeguard. Abstinence from sexual activities involving other people will protect against sexual transmission of sexually transmitted infections. The transfer of and exposure to bodily fluids, such as blood transfusions and other blood products, sharing injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), sharing tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as doctors, haemophiliacs and drug users, particularly at risk.
Recent epidemiological studies have investigated the networks that are defined by sexual relationships between individuals, and discovered that the properties of sexual networks are crucial to the spread of sexually transmitted diseases. In particular, assortative mixing between people with large numbers of sexual partners seems to be an important factor.
Since prostitutes tend to have large numbers of sexual partners, prostitution without the use of safer-sex precautions has often been associated with the spread of sexually transmitted diseases. Some travellers such as truck drivers and sailors also often have high numbers of sexual partners (often prostitutes). However, sexually transmitted diseases are potentially transmitted in any form of sexual relationship, so it is important that all members of the community that are engaged in sexual relationships use safer-sex precautions, regardless of the nature of their relationships.
Prior to the invention of modern medicines, sexually transmitted diseases were generally incurable, and treatment was limited to treating the symptoms of the disease. The first voluntary hospital for venereal diseases was founded in 1746 at London Lock Hospital
The first effective treatment for a sexually transmitted disease was salvarsan, a treatment for syphilis. With the discovery of antibiotics, a large number of sexually transmitted diseases became easily curable, and this, combined with effective public health campaigns against STDs, led to a public perception during the 1960s and 1970s that they had ceased to be a serious medical threat.
During this period, the importance of contact tracing in treating STIs was recognized. By tracing the sexual partners of infected individuals, testing them for infection, treating the infected and tracing their contacts in turn, STI clinics could be very effective at suppressing infections in the general population.
In the 1980s, first genital herpes and then AIDS emerged into the public consciousness as sexually transmitted diseases that could not be cured by modern medicine. AIDS in particular has an asymptomatic period, which allowed the disease to be spread to others, followed by a symptomatic period, which leads rapidly to death unless treated. Recognition that AIDS threatened a global pandemic led to public information campaigns and the development of treatments that allow AIDS to be managed by suppressing the HIV virus for as long as possible. Contact tracing continues to be an important measure, even when diseases are incurable, as it helps to contain infection.
Types and their pathogenic causes
Note: All of the diseases on this list can be 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, and SARS which can be spread through casual contact such as coughing and sneezing, is very often not associated with sexual activity.
- Chancroid (Haemophilus 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 (Hepatitis A and Hepatitis E are transmitted via the fæcal-oral route, not sexually; Hepatitis C is sexually transmittable)
- Herpes /HSV (Herpes simplex virus)
- Human Immunodeficiency Virus (HIV/AIDS)
- Human papillomavirus (HPV)
- Molluscum (MC)
- Severe Acute Respiratory Syndrome (SARS)
- Candidiasis (thrush) (Candida albicans) is not strictly an STD but can be transmitted through sexual contact
- Amoebiasis (Entamoeba histolytica)
- Giardiasis (Giardia lamblia)
- Trichomoniasis (Trichomonas vaginalis)
- Microbicides— Information from Our Bodies, Ourselves on the place of microbicides in the future of STI prevention.
- Information Pictures and list of Symptoms on STDs
- Collection of VD Propaganda Posters
- UNFPA: Breaking the Cycle of Sexually Transmitted Infections
- Sexually Transmitted Diseases/Infections Resource Center from the Association of Reproductive Health Professionals
- Fact sheet on sexually transmitted diseases from the National Institute of Allergies and Infections
- "Sexual networks: implications for the transmission of sexually transmitted infections"
- Sexually Transmitted Disease Information
- Sexually Transmitted Diseases - STD Guide
- 1973 Disney's venereal disease film
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