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This page looks at statistics for syphilis, chalamydia and gonorrhea. Statistics for HIV and AIDS in the USA can be found in our statistics section.

Cases of sexually transmitted diseases reported by state health departments and rates per 100,000 civilian population: United States, 1996-2006

Year	Syphilis				Chlamydia		Gonorrhea
	Primary and secondary		All stages
	Cases	Rate	Cases	Rate	Cases	Rate	Cases	Rate
1996	11,405	4.2	53,240	19.8	492,631	190.6	328,169	121.8
1997	8,556	3.1	46,715	17.1	537,904	205.5	327,665	120.2
1998	7,007	2.5	38,290	13.9	614,250	231.8	356,492	129.2
1999	6,617	2.4	35,383	12.7	662,647	247.2	360,813	129.3
2000	5,979	2.1	31,618	11.2	709,452	251.4	363,136	128.7
2001	6,103	2.1	32,284	11.3	783,242	274.5	361,705	126.8
2002	6,862	2.4	32,919	11.4	834,555	289.4	351,852	122.0
2003	7,177	2.5	34,289	11.8	877,478	301.7	335,104	115.2
2004	7,980	2.7	33,422	11.4	929,462	316.5	330,132	112.4
2005	8,724	2.9	33,288	11.2	976,445	329.4	339,593	114.6
2006	9,756	3.3	36,935	12.5	1,030,911	347.8	358,366	120.9
Change 2001-2006	60%	57%	14%	11%	32%	27%	-1%	-5%

STD reporting

In the United States, the reporting of national surveillance data on Sexually Transmitted Diseases (STDs) does not include all of the most common STDs.

Reporting for gonorrhea and syphilis began in 1941, but chlamydia has only been reported since 1984. The reporting of chlamydia was established when public programmes for the screening and treatment for women were set up to help prevent a complication of chlamydia called Pelvic Inflammatory Disease (PID).

There is no data reporting for genital herpes, genital warts or non-specific urethritis (NSU). Data for these diseases are limited to estimates of the number of the office visits in private physicians' office practices provided by the National Disease and Therapeutic Index (NDTI).

STDs and gender

STD statistics often show an unequal gender distribution, usually with more females infected than males.

Among the chlamydia diagnoses reported in 2006, the male to female ratio was 253,236 to 777,675. For gonorrhea, the male to female ratio was 170,902 to 187,464. As these data demonstrate, the gender divide in chlamydia statistics is much greater than that in gonorrhea statistics. This is partly because more women than men are screened for chlamydia.

In 2006, the numbers of female and male diagnoses of primary and secondary stage syphilis were 8,297 and 1,459 respectively. Of the three main STDs reported, this is the only one that has more male than female cases. To a large extent this can be attributed to syphilis outbreaks among men who have sex with men.

Chlamydia

Increasing numbers of chlamydia infections have made it the most widespread STD in the USA. In 1996 there were 492,631 reported diagnoses, corresponding to a rate of 190.6 per 100,000 population. However, by 2006 the annual total had more than doubled to 1,030,911 and the rate per 100,000 had risen to 347.8.

Cases of chlamydia have increased every year bar one since reporting began in 1984. Much of this rise can be attributed to the expansion of chlamydia screening activities, use of more sensitive screening tests, and improvements in the reporting system.

Yet despite such developments, many women who are at risk are still not being tested. This is partly due to lack of awareness among some health care providers and the limited resources available to support screening. It is estimated that the true number of new chlamydia cases occurring each year is around 2.8 million, most of which are not diagnosed. Chlamydia screening and reporting are expected to continue to expand.

The rate of chlamydia among black Americans was over eight times higher than that of whites in 2006. Rates among American Indian/Alaska Natives and Hispanics were also significantly higher than among whites.

Gonorrhea

In 1978, the annual number of reported gonorrhea diagnoses reached a record high of 1,013,436 - a rate of 459.7 per 100,000 population. Following decreases each year between 1985 and 1997, the annual number of cases has stayed below 365,000, and the rate below 130. True increases or decreases may be masked by changes in screening practices (affected by simultaneous testing for chlamydia), use of diagnostic tests with different sensitivities, and changes in reporting practices. It is estimated that half of gonorrhea cases go unreported.

Although the 2006 rate of 120.9 diagnoses per 100,000 population is one of the lowest ever recorded, gonorrhea remains the second most commonly reported STD in the United States. The rate is still much higher than the "Healthy People 2010" target of 19 cases per 100,000 population.¹ Moreover, the rate of gonorrhea among African Americans was 18 times greater than among whites in 2006. American Indian/Alaska Natives and Hispanics are also disproportionately affected.

Syphilis

Numbers of reported primary and secondary syphilis diagnoses have varied widely since reporting began, from a high of 94,957 in 1946 to a low of 5,979 in 2000. This represents a change from 70.9 cases per 100,000 population to 2.1 cases. Numbers reached another peak of 50,578 in 1990 before decreasing each year in the 1990s. Since the turn of the millennium there has been another rise to 9,186 cases in 2006. This increase is entirely due to more diagnoses in men. More than twice as many men were diagnosed with the condition in 2006 as in 2001, while the number of women has fallen.

Due to the low numbers involved, the Surgeon General in 1999 announced a plan to eliminate syphilis from the USA. However since that year the rate of reported primary and secondary syphilis has risen slightly, and remains a long way from the "Healthy People 2010" target of 0.2 cases per 100,000 population.

Syphilis is a localised infection, with 75% of counties reporting no cases at all in 2006. The disease remains a problem in the South and increasingly in urban areas with large populations of men who have sex with men. Several outbreaks of syphilis have recently been reported in this latter group, possibly reflecting increases in high-risk sexual behaviour. This problem is not confined to the USA, however, and has been reported in similar population groups in the UK.

In 2006, the rate of primary and secondary syphilis was nearly six times higher among African Americans than among whites, reflecting a substantial decrease in disparity over recent years.

Prevalence of STDs among teenage girls

A study presented in 2008 revealed that around 26% of young American women aged 14-19 are infected with at least one of the four most common sexually transmitted infections.² This amounts to around 3.2 million female teenagers. The most widespread infection is HPV (human papilloma virus, which can cause genital warts and cervical cancer), found in 18% of young women. In second place is chlamydia, with a 4% infection rate. The study found that African American teenagers are most severely affected; around 48% of young African American women have an STD, compared to 20% of young white women.

To help combat these infections, the US Centers for Disease Control and Prevention recommends annual chlamydia screening for sexually active women under the age of 25, and HPV vaccination for women and girls aged 11-26.

Top ten states ranked by rate (per 100,000) of reported STD cases: United States, 2006

Rank	Primary and secondary syphilis	Chlamydia	Gonnorhea
1	Louisiana (7.6)	Alaska (681.8)	Mississippi (257.1)
2	Alabama (7.0)	Mississippi (650.5)	South Carolina (242.5)
3	Georgia (6.4)	South Carolina (525.3)	Louisiana (240.6)
4	Nevada (5.7)	New Mexico (509.7)	Alabama (234.0)
5	Maryland (5.4)	Alabama (502.8)	Georgia (216.8)
6	California (5.1)	Hawaii (435.1)	North Carolina (199.4)
7	Texas (4.7)	Georgia (429.6)	Delaware (176.0)
8	Tennessee (4.2)	Delaware (428.6)	Missouri (175.9)
9	New Mexico (4.1)	Tennessee (424.6)	Ohio (167.4)
10	Florida (4.0)	Illinois (419.8)	Tennessee (162.6)

For more information about sexually transmitted diseases, see our STD section.

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