What are sexually transmitted infections?
Sexually transmitted infections (STIs) are infections that are passed from
one person to another during sex. Men, women, and their children can
all be affected by STIs. Some common STIs are gonorrhea, chlamydia,
trichomonas, syphilis, chancroid, herpes, hepatitis B, and HIV.
If a person has any of these signs, he or she may have an STI:
• bad-smelling discharge
• itching genitals
• painful genitals
• sores or blisters on the genitals
• pain in the pelvis or pain during sex
It is also very common to have an STI and have no signs at all.
Many women and men have STIs but do not know it.
Untreated STIs can lead to very serious
health problems, so anyone with an STI
needs treatment as soon as possible. A woman
with an untreated STI can develop a tubal
pregnancy (see page 113), cancer of the
cervix, or can become infertile (see page 30).
An untreated STI in a pregnant woman can
cause a baby to be born too early, too small,
blind, sick, or dead. A person who has one STI
can more easily get another — including HIV.
This chapter describes the most common
STIs and explains how to treat them and
prevent them. It also describes some other
infections of the genitals that are common
but are not transmitted sexually.