Advanced Search
Search Help
STDS TODAY (PRINTABLE VERSION)
What's New
STDs Today
Prevention Today
Making the
Connection
CDC Guidelines and
Recommendations
Program
Management
Counseling, Testing,
and Referral (CTR)
Surveillance and
Data Management
Education and
Outreach
FAQs and Basic
Facts
Sexually transmitted diseases (STDs)
affect men and women of all
backgrounds and economic levels. In
the United States, overall incidence of
STDs has increased dramatically in
recent years.1 The CDC estimates that
19 million new infections occur each
year, almost half of them among young
people ages 15 to 24.2
Despite the fact that STDs are
extremely widespread and add an
estimated $13 billion dollars to the
nation's healthcare costs each year3,
most people in the United States
remain unaware of the risk and
consequences of all but the most
prominent STD—HIV, the virus that
causes AIDS.
Common STDs and the Organisms
That Cause Them
Acquired Immune Deficiency
Syndrome (AIDS)
Chancroid
Chlamydia
Genital Herpes/HSV
Genital Warts/HPV
Gonorrhea
Syphilis
Trichomoniasis
Viral Hepatitis
Other STDs
Who is Infected
Variations in Risk
What Are Some Health Risks of STD
Infection?
What is Being Done?
Order Materials >
View Cart (0)
Specific Searches
Organizations
Materials
News
Conferences
Funding
Learn More
HIV Testing Sites
Satellite Broadcasts
Statistics
Campaigns & Initiatives
Listservs/Mailing Lists
Downloads
Links to Related Sites
RSS News Feed
COMMON STDS AND THE ORGANISMS
THAT CAUSE THEM
Many people are aware of the most
prominent STD—HIV. However, many
other STDs affect millions of men and
women each year. Many of these STDs
initially cause no symptoms, especially
in women. Symptoms, when they do
develop, may be confused with those of
other diseases that are not transmitted
through sexual contact. STDs can still
be transmitted person to person even if
they do not show symptoms. Also,
health problems caused by STDs tend
to be more severe for women than for
men.
Below are descriptions of several of the
most common STDs, including
information about incidence, symptoms
(if any), and treatment.
Back to Top
ACQUIRED IMMUNE DEFICIENCY
SYNDROME
(AIDS)
AIDS (acquired
immunodeficiency syndrome)
was first reported in the United
States in 1981. Since the
beginning of the epidemic, an
estimated 944,306 people have
developed AIDS in the United
States.4 AIDS is caused by the
human immunodeficiency virus
(HIV), a virus that destroys the
body's ability to fight off
infection.
People who have AIDS are very
susceptible to many lifethreatening diseases, called
opportunistic infections, and to
certain forms of cancer.
Transmission of the virus
primarily occurs during
unprotected sexual activity and
by sharing needles used to
inject intravenous drugs.
Learn more about AIDS and
HIV.
Back to Top
CHANCROID
Chancroid
("SHAN-kroid") is
a bacterial
infection caused
by Haemophilus
ducreyi, which is
spread by sexual
contact and results in genital
ulcers. The disease is found
primarily in developing and
third world countries. Only a
few hundred cases a year are
diagnosed in the United States.
The majority of individuals in
the U.S. diagnosed with
chancroid have traveled outside
the country to areas where the
disease is known to occur
frequently.5
The infection begins with the
appearance of painful open
sores on the genitals,
sometimes accompanied by
swollen, tender lymph nodes in
the groin. These symptoms
occur within a week after
exposure. Symptoms in women
are often less noticeable and
may be limited to painful
urination or defecation, painful
intercourse, rectal bleeding, or
vaginal discharge. Chancroid
lesions may be difficult to
distinguish from ulcers caused
by genital herpes or syphilis. A
physician must therefore
diagnose the infection by
excluding other diseases with
similar symptoms. Chancroid is
one of the genital ulcer diseases
that may be associated with an
increased risk of transmission of
the human immunodeficiency
virus (HIV), the cause of AIDS.
People with chancroid can be
treated effectively with one of
several antibiotics.
Learn more about chancroid
infection. En Español.
Back to Top
CHLAMYDIA
Chlamydial ("klaMID-ee-uhl")
infection is a
common sexually
transmitted
disease (STD)
caused by the
bacterium, Chlamydia
trachomatis. Chlamydia is the
most frequently reported
bacterial sexually transmitted
disease in the United States. An
estimated 2.8 million Americans
are infected with chlamydia
each year.6 Under-reporting is
substantial because most
people with chlamydia are not
aware of their infections and do
not seek testing. The highest
rates of chlamydial infection are
in 15- to 19-year-old
adolescents, regardless of
demographics or location.7
According to a 1997 report, the
annual cost of chlamydial
infection was estimated at over
$2 billion.8
Chlamydia can be transmitted
during vaginal, oral, or anal
sexual contact with an infected
partner. A pregnant woman
may pass the infection to her
newborn during delivery, with
subsequent neonatal eye
infection or pneumonia. Even
though symptoms of chlamydia
are usually mild or absent, it
can damage a woman's
reproductive organs and cause
serious complications.
Irreversible damage, including
infertility, can occur "silently"
before a woman ever
recognizes a problem.
Chlamydia also can cause
discharge from the penis of an
infected man, although
complications among men are
rare.
Pelvic inflammatory disease
(PID), a serious complication of
chlamydial infection, has
emerged as a major cause of
infertility among women of
childbearing age.
Chlamydia can be easily treated
and cured with antibiotics.
Learn more about chlamydial
infection. En Español.
Back to Top
GENITAL
HERPES/HSV
Genital herpes is
a contagious viral
infection caused
by the herpes
simplex virus
(HSV) which has
affected an estimated one out
of five (or 45 million)
Americans. There are two types
of HSV, and both can cause
genital herpes. Genital HSV-2
infection is more common in
women (approximately one out
of four women) than in men
(almost one out of five).
Doctors estimate that as many
as 500,000 new cases may
occur each year.9
HSV type 1 most commonly
causes sores on the lips (known
as fever blisters or cold sores),
but it can cause genital
infections through oral-genital
or genital-genital contact. HSV
type 2 most often causes
genital sores, but it also can
infect the mouth. Both HSV 1
and 2 can produce sores in and
around the vaginal area, on the
penis, around the anal opening,
and on the buttocks or thighs.
Occasionally, sores also appear
on other parts of the body
where broken skin has come
into contact with HSV. The virus
remains in certain nerve cells of
the body for life, causing
periodic symptoms in some
people.
Genital herpes infection usually
is acquired by sexual contact
with someone who unknowingly
is having an asymptomatic
outbreak of herpes sores in the
genital area. People with oral
herpes can transmit the
infection to the genital area of a
partner during oral-genital sex.
Herpes infections also can be
transmitted by a person who is
infected with HSV who has
noticeable symptoms. The virus
is spread only rarely, if at all,
by contact with objects such as
a toilet seat or hot tub.
There is no treatment that can
cure herpes, but antiviral
medications can shorten and
prevent outbreaks during the
period of time the person takes
the medication.
Learn more about genital
herpes. En Español.
Back to Top
GENITAL HPV
INFECTION
Human
papillomavirus
(HPV) is one of
the most
common causes
of sexually
transmitted disease (STD) in
the world. Experts estimate that
as many as 24 million
Americans are infected with
HPV, and the frequency of
infection and disease appears to
be increasing. At least 50
percent of sexually active men
and women acquire genital HPV
infection at some point in their
lives. By age 50, at least 80
percent of women will have
acquired genital HPV infection.10
Human papillomavirus is the
name of a group of viruses that
includes more than 100
different strains or types. More
than 30 of these viruses are
sexually transmitted, and they
can infect the genital area of
men and women including the
skin of the penis, vulva (area
outside the vagina), or anus,
and the linings of the vagina,
cervix, or rectum. Low-risk
types of HPV cause genital
warts, the most recognizable
sign of genital HPV infection.
Other high-risk types of HPV
cause cervical cancer and other
genital cancers.11
One study sponsored by the
National Institute of Allergy and
Infectious Diseases (NIAID)
reported that almost half of the
women infected with HPV had
no obvious symptoms. Because
the viral infection persists,
individuals may not be aware of
their infection or the potential
risk of transmission to others
and of developing
complications.12 Most people
who become infected with HPV
will not have any symptoms
and will clear the infection on
their own.
There is no "cure" for HPV
infection, although in most
women the infection goes away
on its own.
In June 2006, the Advisory
Committee on Immunization
Practices (ACIP) voted to
recommend the first vaccine
developed to prevent cervical
cancer and other diseases in
females caused by certain types
of genital human papillomavirus
(HPV). The vaccine, Gardasil®,
protects against four HPV types,
which together cause 70% of
cervical cancers and 90% of
genital warts.13
Learn more about genital warts
and HPV. En Español.
Back to Top
GONORRHEA
Gonorrhea (
gone-or-REE-uh)
is caused by
Neisseria
Gonorrhoeae, a
bacterium that
can grow and
multiply easily in the warm,
moist areas of the reproductive
tract. CDC estimates that more
than 700,000 persons in the
U.S. get new gonorrheal
infections each year. Only about
half of these infections are
reported to CDC.14
The most common symptoms of
infection are a discharge from
the vagina or penis and painful
or difficult urination. The most
common and serious
complications occur in women
and, as with chlamydial
infection, these complications
include Pelvic Inflammatory
Disease (PID), ectopic
pregnancy, and infertility.
Gonorrhea can grow in the
cervix (opening to the womb),
uterus (womb), and fallopian
tubes (egg canals) in women,
and in the urethra (urine canal)
in women and men. The
bacterium can also grow in the
mouth, throat, eyes, and anus.
If it spreads to the blood or
joints it can be life-threatening.
In addition, people with
gonorrhea can more easily
contract HIV, the virus that
causes AIDS. HIV-infected
people with gonorrhea are more
likely to transmit HIV to
someone else.
Several antibiotics can
successfully cure gonorrhea in
adolescents and adults.
However, drug-resistant strains
of gonorrhea are increasing in
many areas of the world,
including the United States, and
successful treatment of
gonorrhea is becoming more
difficult. New antibiotics or
combinations of drugs must be
used to treat these resistant
strains.
Learn more about gonorrhea.
En Español.
Back to Top
SYPHILIS
Syphilis (SIF·i·lis)
is caused by the
bacterium
Treponema
Pallidum. The
incidence of
syphilis has
increased and decreased
dramatically in recent years,
and in the United States, health
officials reported over 32,000
cases of syphilis in 2002.
Between 2001 and 2002, the
number of reported primary and
secondary (P & S) syphilis cases
increased 12.4 percent. Rates
in women continued to
decrease, and overall, the rate
in men was 3.5 times that in
women. This, in conjunction
with reports of syphilis
outbreaks in men who have sex
with men (MSM), suggests that
rates of syphilis in MSM are
increasing.15
Syphilis is passed from person
to person through direct contact
with a syphilis sore. The first
symptoms of syphilis infection
may go undetected because
they are very mild and
disappear spontaneously. The
initial symptom is a chancre
(genital sore); it is usually a
painless open sore that most
often appears on the penis or
around or in the vagina. It can
also occur near the mouth,
anus, or on the hands.
Transmission of the organism
occurs during vaginal, anal, or
oral sex. Pregnant women with
the disease can pass it to the
babies they are carrying.
If untreated, syphilis may go on
to more advanced stages,
including a transient rash and,
eventually, can cause serious
involvement of the brain,
nerves, eyes, heart, blood
vessels, liver, bones, and joints.
Chancres caused by syphilis
make it easier to transmit and
acquire HIV infection sexually.
There is an estimated 2- to 5fold increased risk of acquiring
HIV infection when syphilis is
present.16 The full course of the
disease can take years.
Penicillin remains the most
effective drug to treat people
with syphilis.
Learn more about syphilis. En
Español.
Back to Top
TRICHOMONIASIS
Trichomoniasis (trick-oh-moeNYE-uh-sis) is caused by the
single-celled protozoan
parasite, Trichomonas vaginalis.
It is the most common curable
STD in young, sexually active
women, and it affects men as
well although symptoms are
most common in women. An
estimated 7.4 million new cases
occur each year.17
The vagina is the most common
site of infection in women, and
the urethra (urine canal) is the
most common site of infection
in men. The parasite is sexually
transmitted through penis-tovagina intercourse or vulva-tovulva (the genital area outside
the vagina) contact with an
infected partner. Women can
acquire the disease from
infected men or women, but
men usually contract it only
from infected women.
Most men with trichomoniasis
do not have signs or symptoms;
however, some men may
temporarily have an irritation
inside the penis, mild discharge,
or slight burning after urination
or ejaculation. Some women
have signs or symptoms of
infection which include a frothy,
yellow-green vaginal discharge
with a strong odor. The
infection also may cause
discomfort during intercourse
and urination, as well as
irritation and itching of the
female genital area.
Trichomoniasis can usually be
cured with the prescription
drug, metronidazole, given by
mouth in a single dose.
Learn more about
trichomoniasis. En Español.
Back to Top
VIRAL HEPATITIS
Hepatitis A is a liver
disease caused by the
hepatitis A virus (HAV).
Hepatitis A virus is
spread from person to
person by putting
something in the mouth
that has been
contaminated with the
stool of a person with
hepatitis A. This type
of transmission is called
"fecal-oral." Fewer than
5 percent of infections
are transmitted through
fecal-oral contact during
sexual intercourse. Two
products are used to
prevent hepatitis A
virus infection: immune
globulin and hepatitis A
vaccine.
Hepatitis
B is a
serious
disease
caused by
a virus
that attacks the liver.
The virus, which is
called hepatitis B virus
(HBV), can cause
lifelong infection,
cirrhosis (scarring) of
the liver, liver cancer,
liver failure, and death.
HBV is spread when
blood from an infected
person enters the body
of a person who is not
infected. For example,
HBV is spread through
having sex with an
infected person without
using a condom (the
efficacy of latex
condoms in preventing
infection with HBV is
unknown, but their
proper use might
reduce transmission),
by sharing drugs,
needles, or "works"
when "shooting" drugs,
through needlesticks or
sharps exposures on
the job, or from an
infected mother to her
baby during birth. Of
approximately 200,000
new HBV infections in
the United States each
year, approximately half
are transmitted through
sexual intercourse.
Preliminary data from a
large U.S. multisite
study indicate that
approximately one third
of persons with acute
hepatitis B virus
infections in 1995 had a
history of another
STD.18
Hepatitis C is a liver
disease caused by the
hepatitis C virus (HCV).
HCV is spread primarily
by direct contact with
human blood, including
sharing of needles for
injection drug use and
sex with someone with
HCV. There is no
vaccine to prevent
hepatitis C .
Hepatitis D (delta) is a
liver disease caused by
the hepatitis D virus
(HDV), a defective virus
that needs the hepatitis
B virus to exist.
Hepatitis D virus (HDV)
is found in the blood of
persons infected with
the virus. Infection
occurs when blood from
an infected person
enters the body of a
person who is not
immune. Hepatitis B
vaccine should be given
to prevent HBV/HDV coinfection.
Hepatitis E is a liver
disease caused by the
hepatitis E virus (HEV)
transmitted in much the
same way as hepatitis A
virus. Hepatitis E,
however, does not
occur often in the
United States. HEV is
found in the stool
(feces) of persons and
animals with hepatitis E
and spread by eating or
drinking contaminated
food or water.
At present, there are no
specific treatments for
the acute symptoms of
viral hepatitis. Doctors
recommend bed rest, a
healthy diet, and
avoidance of alcoholic
beverages. A genetically
engineered form of a
naturally occurring
protein, interferon
alpha, is used to treat
people with chronic
hepatitis C. Studies
supported by the
National Institutes of
Health led to the
approval of interferon
alpha for the treatment
of those with chronic
HBV as well.
Learn more about viral
hepatitis.
OTHER STDS
Other diseases that may be
sexually transmitted include
bacterial vaginosis, scabies,
pubic lice, and Pelvic
Inflammatory Disease (PID).
For information on these
diseases and others, visit the
STD section of the National
Institute of Allergy and
Infectious Diseases (NIAID)
Website.
Back to Top
WHO IS BEING INFECTED?
In the United States alone, an
estimated 19 million new cases of STDs
are reported each year.19 This table
shows the incidence and prevalence of
some of the most common STDs.
STD
Chlamydia
Incidenc
e*
2,800,000
Prevalenc
e **
20
***
Gonorrhea
700,00021
***
Syphilis
32,00022
***
(reported)
Herpes
(HSV)
1,000,000 45,000,000
23
24
Hepatitis B
(HBV)
60,00025
1,250,0002
Genital
6,200,000 20,000,000
6
Warts /
Human
Papillomavir
us (HPV)
27
Trichomonia
sis
7,400,000
29
28
***
* Estimated number of new cases each
year
** Estimated number of people
currently infected
*** No recent surveys on national
prevalence for gonorrhea, syphilis, or
trichomoniasis have been conducted.
Variations in risk
STDs affect men and women of
all backgrounds and economic
levels. However, STDs
disproportionately affect
women, infants of infected
mothers, adolescents and
young adults, and communities
of color. Although 15-24-yearolds represent only one-quarter
of the sexually active
population, they account for
nearly half of all new STDs each
year.30
Some contributing factors in the
rise of STDs, particularly among
young people, are that
teenagers are increasingly likely
to have more sex partners at
earlier ages, and sexually active
teenagers often are reluctant to
obtain STD services, or they
may face serious obstacles
when trying to obtain them. In
addition, health care providers
often are uncomfortable
discussing sexuality and risk
reduction with their patients,
thus missing opportunities to
counsel and screen young
people for STDs.31
For more information on at-risk
populations, visit the
Communities at Risk section of
this Website.
Back to Top
WHAT ARE SOME HEALTH RISKS OF STD
INFECTION?
STDs can result in irreparable lifetime
damage, including blindness, bone
deformities, mental retardation, and
death for infants infected by their
mothers during gestation or birth.
In women, STDs can lead to pelvic
inflammatory disease (PID), infertility,
potentially fatal ectopic pregnancies,
and cancer of the reproductive tract.
Back to Top
WHAT IS BEING DONE?
Prevention—both biomedical and
behavioral—is the best hope for
reducing or eliminating STDs.
As the lead agency for STD prevention
in the United States, CDC is tasked with
providing national leadership through
research, policy development, and
support of effective services to prevent
STDs (including HIV infection) and their
complications, such as enhanced HIV
transmission, infertility, adverse
outcomes of pregnancy, and
reproductive tract cancer. The Division
of STD Prevention, part of CDC's
National Center for HIV, Viral Hepatitis,
STD, and TB Prevention, coordinates
CDC's STD prevention efforts.
Back to Top
State of the Nation Report 2005:
Challenges Facing STD Prevention in
Youth
American Social Health Association.
2 Weinstock H, Berman S, Cates W.
Sexually transmitted diseases among
American youth: incidence and
prevalence estimates, 2000.
Perspectives on Sexual and
Reproductive Health 2004;36(1):6-10,
cited in CDC Trends in Reportable
Sexually Transmitted Diseases in the
1
United States, 2004.
3 HW Chesson, JM Blandford, TL Gift, G
Tao, KL Irwin. The estimated direct
medical cost of STDs among American
youth, 2000. Abstract P075. 2004
National STD Prevention Conference.
Philadelphia, PA. March 8-11, 2004,
cited in CDC Trends in Reportable
Sexually Transmitted Diseases in the
United States, 2004.
4 Basic Statistics from HIV/AIDS
Surveillance Report, 2004. Vol. 16.
Atlanta: US Department of Health and
Human Services, Centers for Disease
Control and Prevention; 2005.
5 Chancroid, Medline Plus, U.S. National
Library of Medicine, and the National
Institutes of Health.
6 Chlamydia, CDC.
7 Healthy People 2010, Sexually
Transmitted Diseases.
8 CDC Media Release.
9 Genital Herpes, CDC.
10 Genital HPV Infection, CDC.
11 Genital HPV Infection, CDC.
12 Human Papillomavirus and Genital
Warts, National Institute of Allergy and
Infectious Diseases (NIAID).
13 HPV Vaccine Questions and Answers,
CDC.
14 Gonorrhea, CDC.
15
Syphilis, CDC.
16 Syphilis, CDC.
17 Trichomoniasis, CDC.
18 Alter and Mast, 1994; CDC, 1994b;
Goldstein et al., 1996, cited in The
Hidden Epidemic: Confronting Sexually
Transmitted Diseases (1997), Institute
of Medicine (IOM).
19 Trends in Reportable Sexually
Transmitted Diseases in the United
States, 2004, CDC.
20 Weinstock H, Berman S, Cates W.
Sexually transmitted diseases among
American youth: incidence and
prevalence estimates, 2000.
Perspectives on Sexual and
Reproductive Health 2004;36(1):6-10,
cited in CDC Trends in Reportable
Sexually Transmitted Diseases in the
United States, 2004.
21 Gonorrhea, CDC.
22 Syphilis, CDC.
23 Tracking the Hidden Epidemics 2000.
24 Genital Herpes, CDC.
25 Viral Hepatitis B Fact Sheet, CDC.
26 Viral Hepatitis B Fact Sheet, CDC.
27 Genital HPV Infection, CDC.
28 Genital HPV Infection, CDC.
Trichomoniasis, CDC.
Weinstock H et al., Sexually
transmitted diseases among American
youth: incidence and prevalence
estimates, 2000, Perspectives on
Sexual and Reproductive Health, 2004,
36(1):6–10, cited in Guttmacher
Institute Facts on American Teens'
Sexual and Reproductive Health.
31 Healthy People 2010, Sexually
Transmitted Diseases.
29
30
Back to Top
About Us
HIV Content Notice
Privacy Policy
Policies & Disclaimers
Site Index
The people in the photos on this website are models and used for illustrative
purposes only.
A service of the Centers for Disease Control and Prevention