Introduction
A few decades ago sexually transmitted disease was relatively simple: there was gonorrhea, which was thought to be most common; then syphilis, which was less common and “nongonococcal urethritis”, which could only be determined to be present on clinical grounds, but many authorities were still questioning whether it even existed.
AIDS did not exist and herpes was a rare condition.
Today we know that most venereal diseases are due to chlamydia, which is caused by Chlamydia trachomatis. Others are due to Mycoplasma genitalium or Ureaplasma urealyticum. There still is gonorrhea that used to be “number one” in the past and also the now even less common classical venereal disease, syphilis. However, the feared new “kids on the block” are AIDS and hepatitis C. Strictly speaking hepatitis C belongs to the hepatitis infections, a gastroenterological problem. However, I am mentioning it here as it is intimately connected to peoples’ sexual practices.
I will deal with each sexually transmitted disease separately. The list below shows an overview and the links guide you to the various chapters where more detail can be found.
Sexually Transmitted Diseases (overview)
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Chlamydia trachomatis : Most common VD in the U.S.
Genital herpes : formerly dreaded, now partially responsive to antiviral antibiotics
Genital warts (from HPV) : grow on genitals outside and also on cervix, vagina and male urethra
Haemophilus ducreyi (cause of chancroid) : an acute genital skin infection with painful ulcers and lymph gland infection
Hepatitis C : a gastrointestinal virus affecting the liver. It is transmitted mostly through contaminated needles, less commonly by sexual contact with skin breakdown
HIV (cause of AIDS) : a relatively new viral sexual epidemic, still more common with male homosexual sex and prostitutes
Mycoplasma genitalium : common, but difficult to culture
Neisseria gonorrhea (cause of gonorrhea) : gonorrhea is easy to diagnose in men from urethral discharge, more difficult to diagnose in women (cervical swabs)
Other sexually transmitted disease : linked to sexual practices (anal/oral and oral/genital contamination)
Prevention of sexually transmitted disease (safe sex): one ounce of prevention is worth more than one pound of cure!
Treponema pallidum (cause of syphilis) : the cause of syphilis, a VD with history over the centuries
Trichomonas vaginalis (cause of Trichomoniasis) :infects vagina and male urethra, also causes prostatitis
Ureaplasma urealyticum : also common, but difficult to isolate
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Sexually Transmitted Disease
Hepatitis C
This viral hepatitis and occasionally also hepatitis B are transmitted in more than 45% by sharing of needles when both partners are addicted to injectable drugs.
Otherwise this form of hepatitis is a gastrointestinal disease that affects the liver and that is transmitted through close saliva contact or contact with infected semen that is swallowed. Other means of transmitting the hepatitis virus are contaminated drinking water, tattoo ink or feco-oral contamination. In only 4 to 10% of cases hepatitis C is transmitted sexually. The mechanism of transmission in these cases seems to involve micro-abrasions of the mucous membranes in contact with subsequent mini-exchange of blood through these portals into the blood stream. This mode of transmission through micro-abrasions of mucous membranes is more likely to occur with anal sex (Ref. 4). See link for more details: hepatitis C
Herpes or “genital herpes”
This is a viral skin infection that has been dealt with under that category. Type 2 herpes simplex virus (HSV-2) is the main cause of genital herpes, but 20 to 30% can also be caused by type 1 (HSV-1), which more commonly affects the lips and skin around the mouth. For more details about these viruses see this link: herpes simplex.
Mycoplasma genitalium and Ureaplasma urealyticum
These sexually transmitted bacteria are very difficult to culture and are not assayed routinely in the lab.
As they are covered by the same antibiotics that are effective against Chlamydia, in most cases it is not important to distinguish between these strains. However, there is data to suggest that some of the resistant cases of Chlamydia are sometimes not due to Chlamydia resistance, but rather due to multi-bacterial infection. After Chlamydia has been eradicated these other pathogens stay behind that are more difficult to treat. Mostly they just need longer antibiotic treatment in order to be eradicated. These cases should be referred to a center for sexually transmitted diseases as special tests might be required that can only be done in specialty labs.
References
1.The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 163.
2.James Chin et al., Editors: Control of Communicable Diseases Manual, 17th edition, 2000, American Public Health Association.
3.The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 164.
4. Feldman: Sleisenger & Fordtran’s Gastrointestinal and Liver Disease, 7th ed., © 2002 Elsevier : pages 1306-1307.
