Silent Sexually Transmitted Infections (STIs)

Sexually transmitted diseases, (STDs) are infectious diseases, caused by microbes (mainly bacteria, viruses and protozoans), that are passed from one person to another during sexual activity, including vaginal, anal or oral sex.

Sexually Transmitted Disease or Infection?

Sexually transmitted diseases are also referred to as sexually transmitted infections (STIs). This may seem like a small distinction, but STI is actually a more accurate label for this class of disease, since many sexually transmitted microbes do not cause symptoms of disease in those infected.

Lack of Symptoms Leads to Higher Transmission

The fact that some STDs have very few symptoms, especially in men, is a factor that increases the rate of transmission. Those who do not know they have an infection are unlikely to seek medical treatment, and untreated, they can continue to spread the infection to new sexual partners.

Are Vaccines Available to Prevent STIs?

Vaccinations to prevent STI's are few. Gardisil is a vaccine available to avert human papilloma virus (HPV), the cause of genital warts, some strains of which can result in cervical and oral cancers. There is also a vaccine available against Hepatitis B, a viral infection that can be transmitted sexually, through shared needles and from mother to fetus.

Prevalence of Sexually Transmitted Infections

The American Social Health Organization estimates that one out of four teens in the United States is infected with an STD each year, and by the age of 25, half of all sexually active young adults will have contracted a sexually transmitted disease. In fact, the association between age and risk of becoming infected is staggering.

For example, according to medial microbiology professor Cynthia Schauer, gonorrhea (caused by the Gram-negative bacterium Neisseria gonorrhoea) has a very high prevalence in the US, with 125 infected per 100,000. But this statistic masks an even bleaker story. The incidence of gonorrhea among those age 15 - 19 is 634 per 100,000 (almost 6 times the rate of the general population!) In 20 - 25-year-olds, the incidence is slightly lower, at 460 infected per 100,000.

How Do You Know If You Have an STD?

As the data on gonorrhea suggest, many people who have a STI have no symptoms and no idea that they are infected. Another STI, chlamydia (caused by the Gram-negative bacterium Chlamydia trachomatis) is actually known as "The Silent Disease", since so few of those with chlamydia show symptoms. Only three quarters of infected women and half of infected men are symptomatic.

The best way for a person to find out if he or she has an STD is to get regularly screened. Those who have engaged in unprotected sex (vaginal, anal or oral) are at higher risk and should be tested following sexual contact.

To Learn more about STI's and their prevention, see:
WebMD's Guide to Sexual Health and STDs
CDC web page on Sexually Transmitted Diseases