STDs: Facts, Types, and Symptoms, and Challenges in Treatment

FROM THE LECTURE SERIES: An Introduction to Infectious Diseases

By Barry C. Fox, M.D., University of Wisconsin

Sexually Transmitted Diseases or STDs could affect us in several ways, beyond the obvious public health impact and associated healthcare costs. What are the common STDs that are prevalent in the US? And, how to identify and treat the most common ones?

Image of Stethoscope, syringe, pills with the words Sexually Transmitted Diseases  on wooden background.
STDs are usually contracted through intercourse, oral sex, and skin-to-skin contact with infected sores. (Image: kenary820/Shutterstock)

STDs and their Prevalence in the US

Usually, STDs are contracted through intercourse, oral sex, and skin-to-skin contact with infected sores. However, it is highly unlikely that an STD could be contracted from a public restroom toilet seat.

STDs are often asymptomatic and they could be easily passed along through sexual encounters without either partner’s knowledge. Fifty percent of the new STDs each year are in the age group 15 to 24 years. It would be surprising to know that at least 75% of the population would be exposed to the human papillomavirus (HPV) over their lifetime.

The prevalence of the spectrum of STD disorders in the United States can be viewed as a pyramid. While HIV infection is at the top of this pyramid, the most prevalent genital herpes is at the bottom. The three most prevalent diseases at the bottom of the pyramid are Chlamydia, HPV, and genital herpes virus

This is a transcript from the video series An Introduction to Infectious Diseases. Watch it now, on Wondrium.

Chlamydia Trachomitis

Chlamydia trachomitis has the highest incidence of new cases among all other STDs, with more than one million cases diagnosed in the United States every year.

3D illustration of Chlamydia Trachomatis cells showing elementary bodies (green, extracellular) and reticulate bodies (red, intracellular) floating around.
Chlamydia trachomitis has the highest incidence of new cases among all other STDs. (Image: Kateryna Kon/Shutterstock)

Chlamydia most commonly affects younger adults who are sexually active. However, it does not show any specific bias for age. Cervical infections in females are often asymptomatic. It can ascend into the female reproductive system. This is the number one cause of female infertility in the US.

Fortunately, the testing has become simpler and a urine sample tested by molecular diagnostic tests is reliable for establishing a diagnosis rather than having an invasive pelvic examination or male urethral swabs.

Gonorrhea, the Oldest STD?

Gonorrhea, also known as the clap, is an STD that can cause pelvic inflammatory illness leading to infertility. The history of gonorrhea goes back to biblical times. But one of the first citations about the disease was in the Acts of the English Parliament in 1161, implying that it was a threat to public health even at that time.

Despite having earned the title of the oldest STD, gonorrhea is also the newest. This is due to gonorrhea’s ability to change its genetic structure over time and a new superbug resistant to all antibiotics is now existent. Resistant gonorrhea is now an emerging infectious disease problem. It was cited as a dangerous public health matter by the CDC 2014 resistance report.

Newer Emerging Causes of STDs

As if resistant gonorrhea isn’t enough, there are newer, emerging non-bacterial causes of STDs, including germs known as Ureaplasma and Mycoplasma genitalis.

These latter conditions are difficult to diagnose, but they are usually considered for testing when chlamydia and gonorrhea tests are negative and symptoms still persist.

Learn more about what viruses like HIV and Ebola do to host cells.

Treatment of STDs

There are some characteristics of the disease process that can help differentiate gonorrhea from chlamydia. But when there’s a suspicion of one of the diseases, medical professionals test for both since it is possible to have both simultaneously.

As with so many infectious diseases, these germs used to be sensitive to our old reliable penicillin. The knowledge on emerging infectious disease continues to evolve over time. New microbes are being discovered at every turn.

Yet, the good news is that at present, chlamydia and other in-between germs are treatable with antibiotics, using tetracyclines or erythromycin derivatives that target cellular protein synthesis.

HSV, the Most Prevalent STD

Image depicting genital Herpes in a healthy and infected individual
HSV affects nearly 22% of the American population. (Image: joshya/Shutterstock)

Herpes Simplex Virus or HSV at the bottom of the pyramid is the most prevalent STD in the United States. It affects nearly 22 percent of the population; which equates to between 45 and 60 million Americans with genital HSV infections. The highest prevalence of genital HSV is due to the fact that similar to herpes labialis, it is not cleared and remains latent in the pelvic nerves for life. If the initial genital herpes infection is recognized, there are painful vesicles, similar to fever blisters or cold sores.

The main concern with HSV is that only 10% of individuals actually realize that they are infected. Most of the HSV infections are more subtle and hence most individuals are unaware when they have been infected. This creates a problem, since the virus can be highly contagious.

Transmission and Recurrence of HSV

There are times when herpes virus is actively shed in vaginal or seminal secretions, without the development of visible vesicles on the skin. This accounts for some of the silent HSV transmissions. Recurrences can continue to occur throughout an individual’s lifetime. Yet, they are much more common in the first five years after acquisition of the virus.

The implication of herpes for pregnant women with a history of genital HSV is significant. Medical providers need to be extremely careful that no hidden active disease is present at the time of birthing. Otherwise, the newborn could acquire an illness known as disseminated herpes and/or herpes encephalitis.

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HPV is a ubiquitous virus with an estimated 20 million individuals in the US currently infected and 6 million newly infected annually. The HPV prevalence among girls and women is 27% overall and even 1% of men have genital warts caused by the virus.

The prevalence gradually declines with increasing age since 90% of new HPV infections actually regress over 6 to 18 months. Most HPV infections are not only asymptomatic but they’re too small to be clinically noticeable. Externally, however, infections can be visible as warts.

The most important concern about HPV, however, is that it is implicated in more than 99 percent of cervical cancers. There are over 100 types of HPV and 13 types that can cause cervical cancer. Persistent infection is a prerequisite for progression to cervical cancer.

Common Questions about STDs: Facts, Types, and Symptoms and Challenges in Treatment

Q: What is the most common age group that is affected by STDs?

Fifty percent of the new STDs each year are in the age group 15 to 24 years.

Q: Which STD has the most number of new cases in a specific interval of time?

More than one million cases of chlamydia trachomitis are recognized every year in the United States. It has the highest incidence of new cases among all other STDs.

Q: Which STD has been identified as the cause for cervical cancer?

Human papillomavirus, otherwise known as HPV has been identified as the cause for cervical cancer.

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