The CDC’s annual snapshot of sexually transmitted diseases (STDs) has both good news and bad news for 2013.
On the positive side, the rate of reported cases of chlamydia fell for the first time since national reporting of the disease began, the agency said in the report, “Sexually Transmitted Disease Surveillance 2013.”
The third of the nationally notifiable STDs for which there are federal control programs is gonorrhea, where the incidence rate was slightly down in 2013, after several years of increases.
For all three infections, the agency found, rates among men were increasing, while those for women were falling or stable.
That continues the pattern the CDC reported in last year’s snapshot in which men were driving increased STD rates.
The data come from notifiable disease reporting by state and local STD programs, as well as projects that monitor STDs in various settings, and other national surveys by federal and private organizations, the agency said.
But incomplete diagnosis and reporting means the numbers are an underestimate even for the notifiable diseases, the CDC said, adding that for other STDs, such as human papillomavirus, national estimates aren’t available.
Data on chlamydia show 1,401,906 reported infections from 50 states and the District of Columbia, the report said, corresponding to a rate of 446.6 cases per 100,000 population.
From 1993 through 2011, the rate rose from 178.0 to 453.4 cases per 100,000 population and then was stable in 2012 at 453.3 cases per 100,000. The 1.5% decrease in 2013 represents the first drop since national reporting began.
Women continue to have the most reported infections — some 993,348 cases in 2013 for a rate of 623.1 per 100,000 — at least partly because they are more likely to be screened for the disease, the report said. The rate was a 2.4% decline from 2012.
On the other hand, there were 408,558 cases among males for a rate of 262.6 cases per 100,000 males, up 0.8% from 2012.
The report notes that reported figures for chlamydia, which is mostly asymptomatic, can be affected by changes in the actual incidence, as well as by variation in diagnostic, screening, and reporting practices.
For syphilis, the driving factor is men — and mainly men who have sex with men — the report said.
The annual rate of reported primary and secondary syphilis in the U.S. reached an all-time low in 2000, and rose in the following decade, before decreasing slightly in 2010 and stabilizing in 2011.
But the rate rose in 2012 and again in 2013, when the number of reported syphilis cases increased from 15,667 in 2012 to 17,535 in 2013, an increase of 10.9%. The rate from 5.0 to 5.5 cases per 100,000 population, making both the 2013 case count and rate the highest since 1995.
Among men, the rate of primary and secondary syphilis rose 12% in 2013, compared with 2013 — from 9.2 to 10.3 cases per 100,000 men — while the rate among women remained unchanged at 0.9 cases per 100,000 women.
Men accounted for 91% of all reported primary and secondary disease cases; in the 49 states and the District of Columbia that reported the sex of partners of patients, men who have sex with men accounted for 75% of cases.
In jurisdictions where information for both sex of partner and HIV status was relatively complete — defined as 70% or greater for all cases — 52% of men who have sex with men with syphilis also had HIV. The co-infection rates for men who have sex with women and for women were 9.9% and 5.2%, respectively.
For gonorrhea, there were 333,004 reported cases yielding a rate of 106.1 cases per 100,000 population, which was down 0.6% over 2012. On the other hand, the rate still represented an 8.2% increase over 2009.
Compared with 2012, the 2013 gonorrhea rate among men increased 4.3%, and the rate among women decreased 5.1% — a difference that suggests either increased transmission or increased case ascertainment among gay, bisexual, and other men who have sex with men.