CDC Issues Major New Report on STD Epidemics
Gonorrhea Rates Increase from 1997 to 1999, Suggesting Possible Reversal of Two-Decade Decline; Syphilis Rates at All Time Low; First-of-its-Kind Research on HPV also Released
December 5, 2000
After stabilizing from 1996 to 1997, gonorrhea rates in the United States increased by nine percent between 1997 and 1999, raising concerns that steady declines in the disease over the past two decades could possibly be reversed, according to a new report released today by the Centers for Disease Control and Prevention (CDC).
The statistics on gonorrhea and other STDs are detailed in CDC's biennial report, "Tracking the Hidden Epidemics: Trends in STDs in the United States," released at the National STD Prevention Conference being held December 4-7 in Milwaukee.
"It is too soon to say that successes in gonorrhea control of the past two decades will be reversed, but these new statistics are cause for serious concern," said Helene Gayle, M.D., M.P.H., director of CDC's National Center for HIV, STD, and TB Prevention (NCHSTP). "In the past two years, we have seen signs that gonorrhea is increasing among gay and bisexual men in a number of U.S. cities, and these trends may now be extending to the overall population."
According to Gayle, twenty years of steady improvement in gonorrhea rates, as well as recent improvements in chlamydia and syphilis rates, may have led many to forget that these diseases can have serious consequences, including increased risk of HIV transmission, infertility, and potentially fatal tubal pregnancies. "This rise in gonorrhea rates should serve as a wake-up call to all people at risk that high-risk sexual behaviors continue to have very real consequences."
Prior to the recent upturn, gonorrhea rates declined nearly 10 percent annually from 1985 to 1996, and by 72 percent overall since 1975.
Gonorrhea and Syphilis Rates by City
CDC also released data on the twenty cities with the highest rates of gonorrhea and syphilis in the United States, pointing to several areas where prevention and treatment efforts must be accelerated. While gonorrhea and syphilis are both transmitted sexually, each disease impacts different groups of people and is associated with some differing risk factors.
Unlike gonorrhea, syphilis continued its steady decline since its most recent peak in 1990, falling to 2.5 per 100,000 people in 1999 from a rate of 3.2 per 100,000 in 1997. Both diseases continue to disproportionately affect a number of cities in the South, Midwest and Northeast.
Twelve U.S. cities lead the nation in reported rates of both gonorrhea and syphilis. Cities among the top 20 cities for both diseases (in alphabetical order) in 1999 were: Atlanta, Baltimore, Chicago, Detroit, Indianapolis, Memphis, Tenn., New Orleans, Newark, N.J., Norfolk, Va., Richmond, Va., St. Louis, and Washington, D.C. (See Table.)
Two cities experienced dramatic changes in their reported rates of syphilis compared to 1997. The syphilis rate in Indianapolis increased by nearly 475 percent, from 8.7 per 100,000 people in 1997, to 50 per 100,000 in 1999, following an outbreak of the disease in Spring 1999, making the city the leading U.S. urban center for syphilis rates that year. To fight the epidemic, Indianapolis has extended clinical and prevention services and expanded its community outreach campaign.
Baltimore, which had the highest syphilis rate in the country in 1997, continued to have a relatively high rate in 1999, but managed to cut infections by more than 63 percent, from 101.8 per 100,000 in 1997 to 38.1 per 100,000 in 1999.
"The continued decline in syphilis rates overall is very encouraging and indicates that CDC's National Plan to Eliminate Syphilis in the United States remains a realistic goal," said Ronald O. Valdiserri, M.D., M.P.H., deputy director of CDC's HIV, STD and TB programs. Valdiserri attributed most of the progress to successful efforts to reach African Americans, but added that remaining high-risk areas must be reached.
"Working with state and local health departments, we have increased awareness and access to health care for African Americans, and have reduced the racial disparity in syphilis rates by 30 percent," Valdiserri added. "Our continued efforts to eliminate the disease must focus on places where syphilis remains a significant health threat."
Data released on congenital syphilis indicate a decline of 50 percent, with rates falling from 27.7 in 1997 to 14.3 per 100,000 live births in 1999.
"The fact that the U.S. congenital syphilis rate has been cut in half in just two years is a triumph for the country," said Judith Wasserheit, M.D., M.P.H., director of CDC's STD program. "It is an accomplishment that we must build upon to ensure that no baby is born with syphilis in the United States."
CDC launched the syphilis elimination campaign in October 1999. In 1999, 79 percent of the 3,115 counties in the United States reported no cases of primary and secondary syphilis. Since national syphilis epidemics have occurred in cyclical seven- to ten-year patterns since the initial near elimination of the disease in 1957, CDC's goal is to conquer the disease during this current national downturn.
Chlamydia Positivity by States
CDC also released data indicating that chlamydia remains the most frequently reported infectious disease in the United States. In 1999, 659,441 chlamydia infections were reported to CDC at a rate of 254.1 cases per 100,000 people. While almost 660,000 cases of chlamydia were reported last year, it is estimated that three million new cases of this largely asymptomatic infection occur in the United States each year.
"While chlamydia can easily be treated and cured, the disease can lead to severe health consequences including infertility, potentially fatal tubal pregnancies and increased risk of HIV infection, if not detected early," said Wasserheit. "In areas where people can not easily access screening and treatment services, chlamydia remains a significant and unacceptable health threat, especially among adolescent and young adults."
The percentage of women testing positive for chlamydia -- chlamydia positivity -- in family planning clinics by state provides a good indication of where the disease remains most widespread. For 1999, the twelve states with the highest level of chlamydia positivity among 15-to-24-year-old women in family planning clinics, include (in alphabetical order) Alabama (10 percent), Arkansas (7.1 percent), California (7.2 percent), Georgia (7.7 percent), Illinois (7.2 percent), Louisiana (10.9 percent), Wisconsin (7.2 percent), Mississippi (14.6 percent), North Carolina (8.5 percent), Rhode Island (10.5 percent), South Carolina (9.3 percent) and Texas (9.0 percent).
The latest surveillance data suggests that chlamydia has declined in areas with long-term, widespread screening and treatment programs, but remains at very high levels elsewhere. Currently, federal-funded screening programs for chlamydia and support services cover only 20 percent of at-risk women -- defined as sexually active women who are less that 34 years old and live in poverty -- in 30 states, and 50 percent of at-risk women in the 20 remaining states.
Human Papillomavirus: CDC Releases First-of-its-Kind Research
CDC researchers also reported results of a study of human papillomavirus type 16 (HPV-16), the first study to provide national data on the infection's prevalence in the U.S. population. At any one time, an estimated 20 million people in the United States have genital HPV infections that can be transmitted to others, and every year, about 5.5 million people become infected. There are 30 types of HPV that can infect the genital area. HPV can lead to cervical, penile, and anal cancer, and HPV-16 accounts for 50 percent of all cervical cancer cases.
To obtain the study data, the CDC researchers tested for HPV-16 antibodies, which presumably indicates previous infection, in serum samples taken from a representative population of 7,218 patients participating in the National Health and Nutrition Examinations Survey (NHANES) from 1991 to 1994.
The study, led by CDC researcher Katherine Stone, M.D., revealed that the prevalence of HPV-16 was at least two-fold higher in women compared to men. Women of all races had an HPV-16 prevalence of 17.9 percent, compared to 8 percent for men. African American women age 20 to 29 had the highest prevalence of HPV-16 at 36 percent. African Americans overall had 19.1 percent prevalence, compared to 12.5 percent in whites.
As expected, prevalence of HPV-16 among study participants increased with the number of lifetime sex partners. Seven percent of people with one lifetime sex partner had the infection compared to 20.1 percent of people with 50 or more lifetime sex partners.
Overall, thirteen percent of the study population carried HPV-16 antibodies. However, the figure does not represent all people in the study with the infection because not all people who have been infected develop detectable antibodies.
"HPV is likely the most common STD among young, sexually active people," added Wasserheit. "Given the health consequences of this infection, there is a tremendous need for us to better understand how to prevent HPV infection and why it either persists or is cleared up by the body's immune system, so people do not go on to develop life-threatening complications like cervical cancer."
Some types of HPV cause genital warts, while others cause "subclinical" infections that cannot be seen. Genital warts are extremely common, but can be treated and cured. Subclinical HPV infection, for which there is currently no cure, is much more common than genital warts, although most infections are cleared up by the body's immune system.
HPV is transmitted through sexual contact with the genital area. Because HPV can infect genital areas not covered by condoms, condoms provide incomplete protection. HPV can be prevented by abstaining from sexual activity or having sex only with an uninfected partner.
This article was provided by U.S. Centers for Disease Control and Prevention. Visit the CDC's website to find out more about their activities, publications and services.