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One in five Americans has an STI and nearly HALF of infections are in people under age 24

An estimated one in five Americans has a sexually transmitted infection (STI), a new report finds.

Data published by the Centers for Disease Control and Prevention (CDC) shows there were nearly 68 million STIs on any given day (prevalent) and 26 million newly acquired (incident) STIs in 2018. 

What’s more, almost 50 percent of all incident STIs were diagnosed in those between ages 15 and 24 years old. 

The report also found that STIs acquired that year cost the American healthcare system nearly $16 billion in direct medical costs alone. 

The CDC says its new estimates are critical to ‘better understanding the scope of STIs in the U.S.’ and that more measures are needed to 

New figures from the CDC estimate that on any given day in the U.S. there were 67.6 million sexually transmitted infections (STIs) in 2018

Nearly half, 45.4%, of all newly-acquired infections - for a total of 11.9 million - were among people between ages 18 and 24 (above)

Nearly half, 45.4%, of all newly-acquired infections – for a total of 11.9 million – were among people between ages 18 and 24 (above)

An STI, sometimes called a sexually transmitted disease (STD), is an infection that is passed from one person to another through sexual contact either vaginally, orally or anally.

Some are bacterial infections that are curable with a single-dose regimen of antibiotics while others are viral infections that cannot be cured but can be modulated with antivirals. 

STIs do not always have symptoms and, if left diagnosed and untreated, can have serious health consequences. 

Some infections can increase the risk of HIV or cause chronic pelvic pain, pelvic inflammatory disease and even infertility.

Currently, STIs cause about 2.7 deaths per 100,000 people, primarily due to HIV and HPV (human papillomavirus) infections.

For the report, published in the journal Sexually Transmitted Diseases, the CDC focused on eight STIs: chlamydia, gonorrhea, trichomoniasis, syphilis, genital herpes, HPV, sexually transmitted hepatitis B, and sexually transmitted HIV.  

The number of prevalent and incident infections was calculated by multiplying each STI’s per capita estimate by the full resident population estimate. 

Results revealed an estimated 67.6 million STIs on any given day.

With a population of approximately 320 million people, the authors say this suggests about 20 percent of Americans had an STI at a given point in 2018.

Researchers also found there were about 26.2 million incident STIs in the U.S. in 2018 

The four most common infections were chlamydia, trichomoniasis, genital herpes, and HPV, making up 97.6 percent of all STIs on any given day and 93.1 percent of all newly-acquired STIs. 

Of those new infections in 2018, about half, or 45.4 percent, were contracted by Americans between the ages of 15 and 24. 

‘The burden of STIs is staggering,’ said Dr Jonathan Mermin, director of the CDC’s National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, in a statement.

‘At a time when STIs are at an all-time high, they have fallen out of the national conversation. Yet, STIs are a preventable and treatable national health threat with substantial personal and economic impact.

The new infections will likely cost the U.S. healthcare system an estimated $16 billion in lifetime medical costs, with the most related to HIV treatment (above)

The new infections will likely cost the U.S. healthcare system an estimated $16 billion in lifetime medical costs, with the most related to HIV treatment (above)

What’s more, those new infections will likely cost the U.S. healthcare system an estimated $16 billion in lifetime medical costs. 

Most of the cost, $13.7 billion, is attributed to sexually acquired HIV infections due to the lifetime of antiviral treatment.

The second costliest STI was HPV with about $755 million in treatment for not just the infection but also HPV-related cancers.  

Young people ages 15 to 24 account for about 60% of the combined healthcare costs for chlamydia, gonorrhea and syphilis, according to the CDC.

Women make up nearly 75% of the $2.2 billion in non-HIV-related STI medical costs, the agency said.     

‘There are significant human and financial costs associated with these infections, and we know from other studies that cuts in STI prevention efforts result in higher costs down the road,’ said Raul Romaguera, acting director for CDC’s Division of STD Prevention., in a statement.

‘Preventing STIs could save billions in medical costs, but more importantly, prevention would improve the health and lives of millions of people.’ 



What is it?

Chlamydia is a sexually-transmitted disease that can infect males and females.

It stems from bacteria called chlamydia trachomatis. It is passed through contact, via vaginal, anal or oral sex.

If left untreated it can damage a woman’s fallopian tubes and cause infertility. In very rare cases it can cause infertility in men too.

What are the symptoms?

The majority of people do not feel symptoms of chlamydia. Doctors recommend getting regular STD tests (urine test or swab) to detect it.

However, some do experience some side effects.

Symptoms in women: 

  • Abnormal vaginal discharge
  • Burning feeling when you urinate
  • Pain in the eyes
  • Pain in the abdomen
  • Pain in the pelvis
  • Pain during sex
  • Vaginal bleeding 

Symptoms in men:

  • Discharge from the penis
  • Burning feeling when you urinate
  • Pain and swelling in one or both testicles (rarely)

Symptoms of chlamydia after anal sex:

  • Pain 
  • Discharge
  • Bleeding 

How is it treated?

The infection is easily treated with antibiotics.

Doctors typically prescribe oral antibiotics, usually azithromycin (Zithromax) or doxycycline.


What is it?

A very similar STD to chlamydia, gonorrhea is also bacterial, spread through contact.

It stems from bacteria called Neisseria gonorrhoeae.

What are the symptoms?

Women typically do not see symptoms, but men do.

When a woman does experience symptoms, they are very mild and easily mistaken for a bladder infection.

Doctors recommend getting regular STD tests (urine test or swab) to detect it.

Symptoms in men:

  • Burning feeling when you urinate
  • A white, yellow or green discharge from the penis
  • Painful or swollen testicles 

Symptoms in women: 

  • Burning feeling when you urinate
  • Increased vaginal discharge
  • Vaginal bleeding between periods 

How is it treated?

Gonorrhea is curable with antibiotics, although health officials fear this may be the first ‘untreatable’ STD as the bacteria builds up resistance to our standard methods of treatment.

The CDC recommends treating the infection with a combination of two antibiotics: azithromycin and ceftriaxone.

The infection has already become immune to penicillin, tetracycline and fluoroquinolones.

Increasingly, gonorrhea is building up a resistance to the individual drugs.


What is it?

A chronic bacterial disease, syphilis can be contracted by other means but is typically a sexually-transmitted disease.

In very rare cases, it can be spread through prolonged kissing, as well as the more common routes of transmission: vaginal, anal and oral sex.

It comes from the bacteria Treponema pallidum.

What are the symptoms?

Sufferers develop sores, though these can often go ignored.

The infection develops in stages.

Stage one:

  • Small, painless sores (like ulcers) on genitals or in the mouth
  • Appear within 10-90 days after exposure
  • They disappear within six weeks, and do not leave a scar, before developing to stage two

Stage two: 

  • Rosy rash on the palms of the hand and soles of the feet
  • Moist warts in the groin
  • White patches inside the mouth
  • Swollen glands
  • Fever
  • Weight loss
  • This all fades away without treatment before developing into stage three

Latent syphilis:

Stage three:

  • Without treatment it can progress to more severe issues with the heart, brain and nerves
  • Paralysis
  • Blindness
  • Dementia
  • Deafness 
  • Impotence
  • Death 

How is it treated?

In the early stages, patients can receive an injection of Benzathine penicillin G. This will not undo the internal damage but will eliminate the infection.

For those with latent syphilis – and are unsure how long they had it – doctors recommend having three doses of the penicillin injection, seven days apart from each other.