Question: About this time every year, the CDC issues its annual statistical report about sexually transmitted diseases in the United States. The surveillance report for 2007 has just come out (it takes about a year to compile and process the statistics). It is long—almost 170 pages—and, as usual, disquieting. Our uncomfortable feelings about sexuality have caused STDs to be stigmatizing and, for that reason, often concealed. Hiding infectious diseases and delaying treatment almost always has bad consequences: The untreated STD may silently do terrible damage to the body of the victim, and keeping contacts in the dark promotes spread. So, what does the report say is new with STDs?
Answer: There's been a great increase in sexually transmitted chlamydia infections. This frequently symptomless disease is a common cause of infertility, pelvic pain, and dangerous, abnormally located pregnancies. (It is also responsible for severe eye and lung disease in infants born to infected mothers.) The case rate for the country is now about one per 3,000 inhabitants—more than four times as many as 20 years ago. Adolescents, young adults, blacks, and inhabitants of the mid-South are at especially great risk. Women are especially likely to be diagnosed with chlamydia, but, as with all of the statistics, some of the reported differences may be more apparent than real. Women are tested for chlamydia infections much more frequently than men—though that may change now that the old, pretty unpleasant exam for men is being replaced by a simple urine test.
Gonorrhea, on average about one-third as prevalent as chlamydia, causes similar reproductive harm to women and damage to the eyes of infected newborns. Unlike chlamydia, there hasn't been a dramatic increase in the attack rate, though that may change soon if the bacteria that cause this disease become resistant to cephalosporins, the one effective class of antibiotics we have left to treat it. Until recently, another class—read Cipro—was effective for gonorrhea, but we've had to abandon it, since the organism has become resistant. (Yes, you can blame that development on patients who clamor for antibiotics to treat a cold and the doctors who prescribe them.)
Syphilis is also on the rise—up about 10 percent between 2006 and 2007. Though two-thirds of U.S. syphilis cases occur in men who have sex with men, the diseases is again emerging as a threat to women and infants.
The report also tracked a few other sexually transmitted diseases (but not HIV-1, the cause of AIDS). Genital herpes infections continue to rise every year, as do infections with human papillomavirus. Depending on the strain, these viruses are the cause of genital warts and of cervical and other cancers. We can expect next year's survey—on surveillance in 2008—to show a significant downturn in HPV infections because of the introduction of two very effective vaccines against many of the cervical cancer-causing strains of HPV. (One of the vaccines, Gardasil, also protects against genital warts.)
Next step: It's very easy to misinterpret the data in the report. Many of the STD case rates appear to be rising, and maybe that's accurate. But perhaps the increased numbers reflect increasingly aggressively testing. Maybe less invasive, more comfortable procedures have encouraged those at risk to get tested more frequently. Are the germs really ethnically and geographically prejudiced? Do the very different case rates between ethnic groups reflect biological differences in susceptibility, aspects of cultural style that increase risk, or different financial (and other) community resources that lead to better prevention? Are teens friskier than they used to be or just better tested? Do local circumcision rates make a difference? What's the effect of the loss of federal funding to programs that offer testing and treatment of STDs but also provide abortions?
Perhaps the most important question is: These diseases are all spread the same way—so why are their epidemiological patterns so different? In dissecting those differences, perhaps we will finally be able to pin down the real factors that promote or prevent transmission of each of these diseases. We need to know in order to design the best possible programs so that we can prevent and control sexually transmitted diseases. The annual STD surveillance report is an important first step, but much more is needed.