Sexually Transmitted Diseases in America: How Many Cases and at What Cost?
Prepared for the Kaiser Family Foundation by:
American Social Health Association
December 1998
Editorial Staff:
Linda L. Alexander, Ph.D., F.A.A.N.
President and Chief Executive Officer
American Social Health Association
Joan R. Cates
Vice President of Development and Policy
American Social Health Association
Nancy Herndon
Development Program Manager
American Social Health Association
Jennifer F. Ratcliffe, Ph.D., M.Sc
Epidemiologist
American Social Health Association
American Social Health Association
PO Box 13827
Research Triangle Park, NC 27713
(919) 361-8400
FAX: (919) 361-8425
http://www.ashastd.org
Kaiser Family Foundation
2400 Sand Hill Road
Menlo Park, CA 94025
(650) 854-9400
FAX: (650) 854-4800
http://www.kff.org
Table of Contents
List of Tables and Figures
Tables
Table 1. Strength of Evidence, STD Surveillance Systems
Table 2. Estimated Incidence and Prevalence of STDs, United States, 1996, by Strength of Evidence
Table 3. Estimated Annual Medical Costs of the Major Curable STDs in the United States
Table 4. Estimated Annual Medical Costs of the Major Viral STDs in the United States
Table 5. Estimated Annual Direct Costs of All STDs by State
Figures
Figure 1. Estimated Annual New Cases of STDs
Figure 2. Total Cases of Viral STDs
Figure 3. Distribution of New Cases of STDs by Age
Executive Summary
Sexually transmitted diseases (STDs) have a significant health and economic impact on the American
people. However, the scope of the STD epidemic can be difficult to measure. The most widely quoted
estimate - 12 million annual new STD infections - was published by the Centers for Disease Control
and Prevention (CDC) in 1988. This report updates that estimate. A panel of experts convened by the
American Social Health Association (ASHA) for the Kaiser Family Foundation calculates that the actual
number of new cases of STDs is approximately 15 million annually.
Estimating how many STD cases occur is not a simple or straightforward task. First, most STDs can be
"silent," causing no noticeable symptoms. These asymptomatic infections can be diagnosed only through
testing. Unfortunately, routine screening programs are not widespread, and social stigma and lack of public
awareness concerning STDs often inhibits frank discussion between health care providers and patients
about STD risk and the need for testing. Thus, most STDs go undiagnosed.
Second, of the STDs that are diagnosed, only three - gonorrhea, syphilis, and chlamydia - are
nationally reportable diseases, meaning that health care providers are required to report cases to state health
departments and the CDC. There is no national reporting requirement for the other five major STDs -
genital herpes, human papillomavirus (HPV), hepatitis B, HIV and trichomoniasis. Further, reporting
practices differ between public and private health care sources, as well as among states and individual
providers.
The ASHA panel developed a methodology for weighing the strength of available data, based on the
completeness and consistency of source materials. This methodology was applied to published data using
conservative assumptions to estimate the number of new cases of STDs occurring in 1996, the total
number of existing infections for that year, and the direct medical costs of these cases. It was not possible to
estimate the number of individuals these cases affect, as one person may contract multiple infections.
The ASHA panel estimated that 15.3 million new STD infections occurred in the United States in
1996 (see figure 1). This estimate is larger than the 12 million previously estimated, mainly because
improved detection techniques have made it possible to identify asymptomatic ("silent") infections that
were undercounted in the past. Most notably, the estimates for human papillomavirus (HPV) and
trichomoniasis have increased sharply as a result of new detection and estimation methods and now
account for two-thirds of new cases. However, similar to previous aggregate estimates of STDs, HPV and
trichomoniasis estimates are based on limited data. Therefore, the panel noted that the true number of new
infections could be as low as 10 million or as high as 20 million a year.
It is important to note that the panel's estimates do not reflect an increase in the STD epidemic, but
rather a more accurate count. Overall, the actual number of STD cases has probably decreased slightly.
Better detection methods have allowed more STDs to be treated, which interrupts the chain of STD
transmission. As a result, the incidence of some bacterial STDs (chlamydia, gonorrhea and syphilis) has
fallen, due in large part to national control programs. Behavioral change resulting from awareness of HIV
has also had a positive impact on the spread of STDs.
In addition to new annual cases of STDs, the panel estimated the total (cumulative) number of
cases in 1996 for each of the leading viral infections, herpes, HPV, hepatitis B, and HIV (see figure 2).
These STDs cannot be cured, and thus cases accrue in the population year after year. In summary, the
panel found the following:
Curable (bacterial) STDs
- Chlamydia. The number of new reported
chlamydia cases has risen in recent years, but
this increase is due mainly to more screening
rather than more infections. Overall, as more
infections have been found and cured, the
number of new cases has fallen, from an
estimated 4 million to about 3 million a year.
- Gonorrhea. New cases have continued to
decline over the last two decades, from 1
million in 1977 to 650,000 in 1996. However,
rates remain disproportionately high among
teens and ethnic minorities.
- Syphilis. Rates of syphilis in the U.S. are
at the lowest levels in 20 years, at 70,000 new
cases annually. Infection levels are so low that
the CDC, Division of STD Prevention, has
concluded it is possible to eliminate syphilis
in the United States.
- Trichomoniasis. "Trich" is the most
common curable STD among young, sexually
active women, with an estimated 5 million new
cases a year.
Incurable (viral) STDs
- Genital herpes. This lifelong viral infection
has grown by 30% in the last two decades,
to at least 45 million cases. Genital herpes now
affects more than 1 in 5 Americans over the age
of 12. One million new cases occur each year.
Most herpes infections do not cause noticeable
symptoms but can still be transmitted.
- Human Papillomavirus (HPV). Some 5.5
million new infections occur each year, with at
least 20 million people currently infected. It is
not known whether HPV infections are
lifelong. Cervical HPV infection has been
linked with cervical cancer.
- Hepatitis B. Despite the availability of a
vaccine, hepatitis B remains a leading STD,
with 77,000 new cases a year acquired through
sexual transmission. A total of 750,000 people
are infected with hepatitis B as a result of
sexual transmission.
- HIV/AIDS. The annual number of new
HIV cases in the United States has been stable
for several years, with about half - 20,000
infections per year - of new cases acquired
through sexual transmission. The majority of
new cases are in ethnic minorities. About
500,000 Americans are infected with HIV as a
result of sexual transmission.
The panel reviewed published data on the economic costs of individual STDs and estimated the
direct medical costs of STD treatment for all estimated cases in the United States per year to be at least
$8.4 billion. In addition to the economic impact of STDs, the panel noted that STDs have a high
human cost in terms of pain, suffering and grief. Finally, the panel derived state-by-state estimates of
STD cases and their direct medical impact by distributing the national STD burden across states
according to the percentage of sexually active unmarried 15-24 year old men and women in each state.
As better data become available through the CDC and other sources, the methodology developed by
the ASHA panel can be used to estimate STD cases and costs more accurately. In the meantime, the
estimates in this report represent the best and most current numbers on which to base policy decisions,
medical cost allocations, and public education concerning this important health issue.
ASHA Panel To Estimate Std Incidence, Prevalence And Cost
Willard Cates, Jr., M.D., M.P.H. (Chair)
Family Health International, Research Triangle Park, NC
Gail A. Bolan, M.D.
California Department of Health Services, Berkeley, CA
Virginia Caine, M.D.
Indiana University School of Medicine
Marion County Health Department, Indianapolis, IN
Jacqueline Darroch, Ph.D.
The Alan Guttmacher Institute, New York, NY
Edward W. Hook, III, M.D.
University of Alabama at Birmingham, Birmingham, AL
James G. Kahn, M.D., M.P.H.
Institute for Health Policy Studies
University of California at San Francisco, San Francisco, CA
William J. Kassler, M.D., M.P.H.
Division of STD Prevention
Centers for Disease Control and Prevention, Atlanta, GA
Stephen Morse, Ph.D.
Division of AIDS, STDs, & TB Laboratory Research
Centers for Disease Control and Prevention, Atlanta, GA
Michael E. St. Louis, M.D.
Division of STD Prevention
Centers for Disease Control and Prevention, Atlanta, GA
James Trussell, Ph.D.
Office of Population Research
Princeton University, Princeton, NJ
Anna Wald, M.D., M.P.H.
University of Washington, Seattle, WA
ASHA Staff
Linda L. Alexander, Ph.D., F.A.A.N.
President and Chief Executive Officer
Joan R. Cates
Vice President of Development and Policy
Jennifer F. Ratcliffe, Ph.D., M.Sc.
Epidemiologist
Nancy Herndon
Development Program Manager
Introduction
Sexually transmitted diseases (STDs) are among the most common infections in the United States.
In 1996 one STD - chlamydia - was the most frequently reported infectious disease in the country,
according to the Centers for Disease Control and Prevention (CDC). Of the top 10 most frequently
reported infections, five are STDs. Most Americans are unaware of the extent of the STD epidemic,
however, because many infections are asymptomatic, and because social stigma prevents open discussion
of the topic.
The silent nature of the STD epidemic is perhaps its greatest public health threat, as people continue
to underestimate their risk or forgo testing because they have no symptoms. In addition, a potentially
deadly aspect of STDs is the link to HIV. STD infections increase susceptibility to acquiring HIV, the
virus that causes AIDS. Clearly the continued spread of STDs is costly in terms of both health care
dollars and human suffering. However, many effective treatments and prevention strategies exist that can
help stop the STD epidemic if we understand who is affected and the cost-effectiveness of prevention.
Who Is Affected?
Americans of every age and every geographic, racial, cultural, socioeconomic, and religious
background are affected by STDs. Infections such as herpes and HPV are so prevalent that almost
everyone is at risk, and many are already infected.
Impact on Teens and Young Adults. More than
half of teens ages 15-19 have had sex, and these
teens are at high risk for STDs. About a quarter
of all new cases of STDs occur in teens; two-thirds
of cases occur in people ages 15-24 (see
figure 3). By age 24, at least one in three sexually
active people will have contracted an STD.1
Why are young people at such great risk? They
are more likely to be single, have multiple sex
partners and to engage in other risky behaviors
than older people. In addition, teenage girls are
highly susceptible to contracting chlamydia and
gonorrhea, because these diseases easily infect the
immature cervix.
Impact on Women. Biologically and socially,
women are more vulnerable than men to STDs.
Genital infections including HIV are more easily
passed from men to women than from women to
men. Women are less likely to have noticeable
symptoms unless complications occur. They are
then more likely to experience long-term
consequences such as infertility, tubal pregnancy
and cervical cancer. Many women face obstacles
protecting themselves from STDs: in general,
women have less say than men over whether to
have sex, and whether condoms are used.
Impact on Infants. Virtually every STD can be
passed from a pregnant woman to her fetus or
infant, often with tragic consequences. Because
infants' immune systems are still developing,
infections that are serious for an adult can be life-threatening
for an infant. Common STD-related
problems for infants include low birth weight,
premature birth, conjunctivitis, pneumonia,
neurologic problems, and congenital
abnormalities.
Impact on Other Groups. Other groups
disproportionately affected by STDs include
people who are poor, lack access to health care,
and are geographically isolated, including ethnic
minorities, who often fall into all these groups.
Within the United States, some STDs -
particularly gonorrhea, chlamydia, syphilis and
HIV - tend to be highest in Southern states.
Overall, however, STD rates do not vary greatly
by region.
What Is Being Done?
Several strategies have proven effective at lowering rates of STDs in the United States. Most notably,
CDC and state and local programs for the control of chlamydia, gonorrhea and syphilis have dramatically
reduced the numbers of these infections. Education and counseling programs have changed sexual behaviors
in some high-risk communities. In addition, new diagnostic techniques are helping health care providers
find and treat many asymptomatic infections. New, single-dose treatments are available to cure bacterial
STDs and provide safe options for treating pregnant women. National media have also played a key role in
educating the public about STD prevalence and risk.
The Unmet Need
Despite these advances in treatment and prevention, however, the United States continues to have the
highest STD rates of any country in the industrialized world.
2
No effective national program for STD
prevention exists, and state programs vary widely in funding and impact. The American public remains
generally unaware of the risk for STDs and the importance of prevention and screening.
A 1998 Kaiser Family Foundation/
Glamour magazine survey found that most men and women of
reproductive age (18-44 years old) seriously underestimate how common STDs are and their personal
risk for getting an STD.
3
While an estimated one in four Americans will get an STD in their lifetime,
4
the majority of men (74%) and women (69%) think the rate is one in ten Americans or fewer. Only 14
percent of all men and 8 percent of all women say they think they are at risk for STDs - and single
men and women are not much more likely to feel they are at risk. Perhaps for this reason, condom use is
far from consistent among many couples; two-thirds of single men and women say they do not "always"
use condoms. The story is similar among teens 15-17 years: the majority of teen girls (73%) and boys
(77%) think the STD rate is one in ten Americans or fewer in a lifetime. Only one in five teens say they
think they are at risk of getting an STD.
The secrecy and shame surrounding STDs interfere with communication between parents and
children, sexual partners, teachers and students, and even patients and health care providers. In a Gallop
Organization poll commissioned by ASHA in 1995, over half of adults and over one-third of teens said
their health care providers spend "no time at all" discussing STDs with them.
5
Another Kaiser Family
Foundation/
Glamour survey conducted in 1997 found that STDs are rarely discussed during OB/GYN
visits, and that providers may not be asking adequate risk-assessment questions.
6
As greater numbers of
Americans receive their health care through managed care organizations, it will be critical for these and
other private health care providers to take the initiative in counseling, screening, diagnosing and treating
patients for STDs. Teenagers, in particular, need and deserve better information, counseling and access
to health care.
There is a clear need for public and private sector organizations, medical professionals, educational
systems, the media, and religious and community groups to break the silence on the topic of sexual
health. Public education programs are essential to alert consumers, health care providers and policy
makers to the reality of the STD epidemic. The mass media can be extremely powerful in promoting
healthy behaviors and balanced sexual messages.
Clearly, more progress is needed and is feasible. With the currently available testing and treatment
technologies, the United States has never had better tools for addressing its large and costly STD
epidemic. Effective prevention to reduce the spread of STDs now can prevent both growing health
care costs and continued human suffering.
Notes and References
1. Calculated by the ASHA panel based on the following data:
HPV has been shown to infect more than 40% of sexually active college students; genital herpes infects 12% of the American population by age 24; and chlamydia infects 5- 10% of women ages 15-24.
2. Eng, TR, and Butler, WT, eds,
The Hidden Epidemic: Confronting Sexually Transmitted Diseases Washington, D.C.: National Academy Press, 1997.
3. Kaiser Family Foundation/Glamour,
1998 Survey of men and women on sexually transmitted diseases. Menlo Park, CA.
4. Calculated by the Alan Guttmacher Institute (AGI) on the basis of CDC incidence data and estimates.
Donovan, P., Testing Positive: Sexually transmitted disease and the public health response. The Alan Guttmacher Institute, Washington, D.C., 1993.
5. American Social Health Association/Gallop Organization,
Teenagers know more than adults about STDs, but STD knowledge among both groups is low. Research Triangle Park, NC, 1995.
6. Kaiser Family Foundation/Glamour,
1997 National survey - talking about STDs with health professionals: Women's experiences. Menlo Park, CA.
