Below are some fast facts about the most common STDs in the United States. These statistics are based on findings released by the US Center for Disease Control (CDC) in 2009.

Chlamydia:

• Chlamydia is the most commonly reported infectious disease in the United States.
• In 2008, there were more than 1.2 million reported cases of Chlamydia (1,210,523)
• Note: CDC research in indicates that mot Chlamydia cases go undiagnosed and therefore unreported as many of those infected never experience symptoms. Because of this, it is estimated that there are an estimated 2.8 million cases in the US each year.
• The rate of infection in the US is 401.3 cases per 100,000 population
• Women, especially young and minority women, are most at risk for Chlamydia infection. In 2008, girls 15 to 19 years of age had the highest numbers of reported cases (342,875) and highest rates of Chlamydia (3,275.8 per 100,000 females) infection.
• In 2008, there were 323,696 reported cases of infection among young women 20 to 24 years of age.
• There was a 45% increase in Chlamydia infection among men, between 2004 and 2008.

Gonorrhea:

• Gonorrhea is the second most commonly reported infectious disease in the United States.
• In 2008, there were 336,742 reported cases of Gonorrhea infection
• The rate of infection in the US is 111.6 cases per 100,000 population
• After a 74% decline in the rate of reported Gonorrhea from 1975 through 1997, overall infection rates have remained relatively stable for the past decade, though the disease persists at a high level. Like Chlamydia, Gonorrhea is substantially under-diagnosed and under-reported, and CDC estimates that there are approximately twice as many new Gonorrhea infections each year as are reported.
• Since 2000, rates of infection between men and women have remained similar. In 2008, the Gonorrhea rate among women was 119.4 cases per 100,000 - compared to 103.0 among men.
• Rates of infection are highest among adolescent girls and young women. In 2008, girls 15 to 19 years of age and young women 20 to 24 years of age had the highest rates of Gonorrhea (636.8 and 608.6 cases per 100,000 females, respectively).

Syphilis:

• Although on the verge of elimination less than a decade ago, Syphilis re-emerged as a public health threat in 2001 and rates have steadily increased since then.
• In 2008, there were 13,500 reported cases of primary and secondary Syphilis (the most infectious stages of the disease) — the highest number of cases since 1995 .
• In 2008, the national rate of Syphilis infection was 4.5 cases per 100,000 population, an 18 percent increase from 2007 (3.8).
• The majority of reported Syphilis cases in the United States continues to be among men who have sex with men (MSM). In 2008, data showed that 63 percent of P&S syphilis cases were among MSM, compared to only 4 percent of cases in 2000.
• Rates of infection among women have increased each year since 2004, following more than a decade of declines. In 2008, the Syphilis rate among women increased 36 percent from the previous year (1.1 cases per 100,000 females in 2007 vs. 1.5 in 2008).
• In 2008, there were 431 reported cases of congenital Syphilis (transmission from mother to infant during childbirth) - 10.1 cases per 100,000 live births.