Sexually transmitted diseases

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Sexually transmitted diseases (STDs) are infectious diseases transmitted primarily by sexual contact, but many are acquired in other ways as well. The agents that cause these diseases include viruses, bacteria, protozoa, and arthropods. Historically, illnesses passed by solely sexual contact were called venereal diseases, after Venus, the Roman goddess of love. In the pre-antibiotic era, when toxic heavy metal-containing compounds were the only effective remedies for syphilis, the standing joke among medical students was "one night on Venus and the rest of your life on Mercury". This page will provide an overview on the most common STDs. For more detailed information, please visit the main article on each disease.

Viruses[edit]

Human Immunodeficiency Virus (HIV)

HIV is an infectious human retrovirus that causes Acquired Immunodeficiency Syndrome (AIDS). It is primarily a sexually transmitted disease. Currently, HIV/AIDS kills approximately 2-3 million people per year, primarily in developing countries. In the U.S., there are approximately 500,000 people infected with HIV.[1] After exposure, the virus invades and replicates in immune cells near the site of infection. It quickly spreads to regional lymph nodes and via the blood stream to the rest of the body. During this stage the patient may experience Acute Retroviral Syndrome, a vague flu-like illness that may also include rashes, night sweats, fevers, and joint pains. The patient is often asymptomatic for the first 5-10 years after infection. By that time, untreated, progression to AIDS in inevitable, except in a small subset of patients.

Herpes Simplex Virus (HSV 1 and 2)

File:STD 47.jpg
Herpes on male genitalia
Herpes simplex "cold sores"
File:STD 50.jpg
Herpes on female genitalia

Herpes can appear on either the lips or the genitalia. It usually presents as a painful, bumpy rash, sometimes with fever. The majority of oral herpes is caused by Type I, most cases of genital herpes by Type II. Herpes is transmitted by skin-to-skin contact. The first outbreak is often the worst, with significant systemic symptoms, such as fever and malaise. After the rash resolves, the virus remains dormant in the local nerve root, and may recur at any time. The illness if life-long. Herpes is transmissible both during outbreaks, and during dormancy.

Human Papilloma Virus (HPV)

HPV often presents as anogenital warts, or as an abnormality on a pap smear. These lesions can be pre-cancerous. HPV is the causative agent of cervical cancer and anal squamous cell carcinoma.

Human papillomavirus (HPV) is a sexually transmitted disease affecting both men and women. According to the Center of Disease Control (CDC) HPV has over 100 strains, 30 of them are sexually transmitted. Out of the 30 sexually transmitted strains, there are high risk and low risk types. High risk types can cause abnormal Pap tests and may also lead to cancer of the cervix, vulva, vagina, anus, or penis. Low risk types are mostly responsible for genital warts. It is common for HPV to have no signs and symptoms. A common symptom is genital warts. The warts can be big, small, raised or flat, and there can be many or just one. The CDC states that approximately 20 million people are currently infected with HPV. At least 50 percent of sexually active men and women acquire genital HPV infection at some point in their lives. By age 50, at least 80 percent of women will have acquired genital HPV infection. About 6.2 million Americans get a new genital HPV infection each year.

HPV is commonly diagnosed through abnormal Pap test. A Pap test screens for cervical cancer. The CDC also states there are four HPV types, which together cause 70% of cervical cancers and 90% of genital warts. They go on to say that approximately 10 of the 30 identified genital HPV types can lead to the development of cervical cancer. A Pap test is the only way to detect pre-cancerous and cancerous cells. The American Cancer Society estimated in 2004, that about 10,520 women would develop invasive cervical cancer and about 3,900 women would die from the disease.

In order to reduce one’s risk for HPV it is necessary to avoid genital contact with another individual. If one chooses to be sexually active they should always practice safe-sex; this includes wearing latex condoms. It is also very important for women to get regular Pap tests if they are sexually active.

The HPV vaccine is the first vaccine ever developed to prevent cervical cancer, precancerous genital lesions, and genital warts due to the human papillomavirus (HPV). The vaccine is available for women between the ages of 9 and 26 and recommended prior to becoming sexually active. The HPV vaccine protects against four types of HPV (6, 11, 16, 18) which cause 70% of cervical cancers and 90% of genital warts. The vaccine is given in a series of three shots over a 6 month period.

This groundbreaking vaccine is nearly 100% effective in protecting against diseases caused by the four HPV types previously mentioned. This includes protecting against precancers of the cervix, vulva and vagina, and genital warts. The FDA and CDC have licensed the HPV vaccine as safe and effective after testing it in over 11,000 females ages 9 to 26 around the world. These studies have shown no serious side effects. The most common side effect is temporary soreness at the injection site.

This vaccine has not been widely tested on men, women over the age of 26 or under the age of 9, or women who are pregnant and is not recommended for these groups.

Although the vaccine is recommended before the onset of sexual activity, women who are sexually active may also benefit from vaccination. If a woman is currently infected with one type of HPV, the vaccine can still protect her from the other three types. However, it is not effective in treating current infections. The vaccine is also not effective in protecting other sexually transmitted infections or unwanted pregnancies. Contraceptive measures should continue to be used.

Because the HPV vaccine does not protect against ALL types of HPV that cause cervical cancer, it is important to continue to get regular cervical cancer screenings.


Hepatitis B and C Viruses (HBV, HCV)

These are often asymptomatic, but over time can lead to cirrhosis and liver cancer. If any symptoms are present, the illness can look like any hepatitis, that is, jaundice, change in urine or stool color, abdominal swelling, fatigue, joint pain, itchiness, nausea, and a loss of appetite. About 70% of adults experience these symptoms, and hepatitis symptoms often do not manifest until 3 months after exposure.

Bacteria[edit]

Neisseria gonorrhoeae (gonorrhea, "the clap")

Photomicrograph of N. gonorrhoeae seen as typical gram-negative diplococci

In males, this presents as a purulent (usually white or green) penile discharge. Women may have a vaginal discharge, or no symptoms at all. Gonorrhea infection in women can lead to pelvic inflammatory disease and infertility. Gonorrhea is believed to cause approximately 700,000 new infections yearly in the U.S., about half of which are reported. [2] Emergence of fluoroquinolone-resistant strains of Gonococcus has been documented over the past decade, with highest incidence in Asia, and resistant strains being detected more frequently in the western United States (Source: http://stdtests.us/gonorrhea.html).

Chlamydia trachomatis (chlamydia) Chlamydia is a very common disease. In contrast to Gonorrhea, rates are rising. A 1998 study of female military recruits showed a disease prevalence of 9.2%[3] This presents similarly to gonorrhea, but is often asymptomatic, and is commonly without the patient knowing they are ill. In 2004, almost one million cases were reported in the United States. [4]

Treponema pallidum (syphilis)

T. pallidum on dark field microscopy
Painless chancre of primary syphilis on shaft of penis

This organism causes syphilis, a multisystem disease.

Protozoa[edit]

Trichamonas vaginalis ("trich")

In females, this usually presents as a foul vaginal discharge, but males are usually asymptomatic. Even though males are asymptomatic, partners of infected females must be treated.

Giardia lambia Giardia is a common water-borne diarrheal illness, but can also be contracted through certain sexual practices, such as oral-anal sexual contact.

Arthropods[edit]

Pubic lice ("crabs")

This presents as itching in the groin, and often small parasites are easily visible.

Scabies

This often presents as itching, with rash being more prominent between the fingers and toes.

Prevention[edit]

Latex condoms have been proven to protect against many, but not all, STDs. Abstinence from any sexual contact reduces risk, but since sexual contact also occurs in marriage, other consentual relationships, and in rape, it is not a viable method of prevention. Vaccines are not widely available for STDs. An HPV vaccine has recently been released for protection against the most common oncogenic strains of HPV.

References[edit]

  1. CDC HIV/AIDS Surveillance Report:HIV Infection and AIDS in the United States and Dependent Areas, 2005.
  2. CDC:Sexually Transmitted Disease Surveillance 2004 Supplement:Gonococcal Isolate Surveillance Project (GIST) Annual Report-2004. Atlanta, GA:United States Department of Health and Human Services, December 2005.
  3. Chlamydia trachomatis Infections in Female Military Recruits. Gaydos C. A., Howell M. R., Pare B., Clark K. L., Ellis D. A., Hendrix R. M., Gaydos J. C., McKee K. T., Quinn T. C. N Engl J Med 1998; 339:739-744, Sep 10, 1998.
  4. Centers for Disease Control and Prevention. Sexually Transmitted Disease Surveillance 2004 Supplement, Chlamydia Prevalence Monitoring Project. Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, December 2005.