and QUALITY OF LIFE. STDs infect tens of millions of
people in the United States and hundreds of mil-
lions of people throughout the world.
STDs may not have symptoms though the per-
son continues to be infectious (capable of passing
the STD to sex partners). Often a person has more
than one STD at the same time, a circumstance
called co-infection. It is possible for reinfection
with the same STD to occur after treatment.
ANTIBIOTIC MEDICATIONSare the mainstay of treat-
ment for bacterial STDs. ANTIVIRAL MEDICATIONS
may alleviate symptoms in viral STDs such as GEN-
ITAL HERPESand lessen the risk for transmitting the
VIRUSto others, though the virus often remains in
the body and symptoms recur.
Though all STDs are treatable, many are not
curable. Some, such as HEPATITIS B and HUMAN
PAPILLOMAVIRUS(HPV), are known causes of cancer
(LIVER CANCERand CERVICAL CANCER, respectively).
Hepatitis C may be fatal and at present HIV/AIDSis
always fatal, though treatment and supportive
lifestyle measures can manage both conditions for
years to decades. STDs are a leading cause of PELVIC
INFLAMMATORY DISEASE(PID) in women, a serious
INFECTIONthat can result in INFERTILITYby causing
scarring and occlusion (blockage) of the FALLOPIAN
TUBESand sometimes the CERVIX.
Oral contraceptives (birth control pills),
intrauterine devices (IUDs), cervical
diaphragms, spermicides, VASECTOMY,
TUBAL LIGATION, and HYSTERECTOMY,
though effective methods of CONTRACEP-
TION, do not prevent INFECTIONwith SEX-
UALLY TRANSMITTED DISEASES(STDS).Abstinence (no sexual partners) is the most
effective means to prevent infection with STDs.
Among people who are sexually active, key meas-
ures to reduce the risk for STD infection are
- long-term, mutual monogamy (one exclusive
sex partner) - male latex condom use with every sexual act
(vaginal intercourse, anal intercourse, oral sex,
partner MASTURBATION)
The effectiveness of these measures varies for
the specific STD. Latex condoms are highly effec-
tive for preventing GONORRHEAand HPV, for exam-
ple, though may be less effective for protecting
against genital herpes and HIV/AIDS. The female
condom is another barrier method of CONTRACEPTION
that provides some, but more limited, protection
from STD infection compared to the male condom.
Unprotected contact with bodily fluids (pre-ejacu-
late or vaginal secretions), such as may occur dur-
ing heavy petting and foreplay, carries the same risk
for STD infection as does actual intercourse.
Infections not typically characterized as STDs,
such as TUBERCULOSIS, may also pass between people
during sexual activity. Conversely, some infections
characteristically transmitted through sexual con-
tact may also pass via other means such as shared
needles among intravenous DRUG users (notably
HIV/AIDS and hepatitis). An infant may acquire
gonorrhea, CHLAMYDIA, and genital herpes during
CHILDBIRTH(passage through the VAGINA). An infant
may also acquire congenital herpes without passing
through the birth canal if the mother first becomes
infected when she is pregnant.
Because many STDs are highly contagious and
prompt treatment can minimize their spread as
well as prevent long-term health complications for
infected individuals, health experts strongly
encourage diagnostic testing and treatment for all
sexual partners of everyone who acquires an STD.
In the United States, community health centers
and public health services provide low-cost or free
STD testing and treatment. Private doctors and
other health-care providers also diagnose and
treat STDs.
See also ANTIBIOTIC RESISTANCE; SEXUAL HEALTH;
SEXUALLY TRANSMITTED DISEASE(STD) PREVENTION.sperm The male cells of reproduction, also called
gametes. A spermatozoon (single sperm cell) is a
haploid cell; it contains one half of the genetic
material necessary for human life. The epididymis
within the testicle (also called the testis) produces
sperm, a process called spermatogenesis, at the rate
of hundreds of millions each day from PUBERTY(the
onset of sexual maturity) through the end of life.
The tissues of the TESTICLES absorb sperm that
remain in the epididymis for longer than six weeks,
allowing the supply of sperm to remain fresh.
Spermatogenesis The production of new sperm
cells begins with the division and differentiation of340 The Reproductive System