There is an unending epidemic of infectious diseases in the United States: sexually transmitted diseases. The Centers for Disease Control and Prevention (CDC) reports 20 million new cases of STDs crop up annually - all stemming from eight viruses and bacteria, according to Live Science.

If 20 million doesn't impress you, consider the length of time these infections plague their host. At any point in time, there are 110 million current STDs in the United States alone, according to Live Science.

The most common STDs on American soil are chlamydia, gonorrhea, hepatitis B virus (HBV), genital herpes, HIV, human papillomavirus (HPV), syphilis and trichomoniasis, according to Live Science. Chlamydia and HPV are the top ranking newly-acquired infections.

Per data from 2008, the CDC reported that an average of 50.5 million of existing infections are in men, while 59.5 million are in women.

Medical costs directly related to new cases of STDs number $16 billion, according to Live Science. Young people between the ages of 15 and 24 can claim 50 percent of those new infections, although the 15- to 24-year-old age group only comprises a quarter of sexually active people.

Current data places an estimate of 1.8 million people in the U.S. with chlamydia and a rising number of cases of syphilis, despite the infection almost disappearing a few years ago.

Many STDs go undiagnosed, ergo, unreported (like chlamydia, gonorrhea and syphilis) and others are not part of routine reports to the CDC (such as HPV, herpes and trichomoniasis), so the reported numbers of infections might only represent a small portion of STDs in the United States, according to Live Science.