chlamydia Illness resulting from INFECTIONwith
the bacterium Chlamydia trachomatis. Chlamydia is
one of the most common SEXUALLY TRANSMITTED DIS-
EASES(STDS) in the United States, infecting an esti-
mated three million people each year. However,
fewer than a third seek treatment because their
symptoms are mild or they do not have symptoms
and do not know they have chlamydia. Half of
men and two thirds of women who have chlamy-
dia experience no symptoms, though they
nonetheless pass the infection to their sex part-
ners. Doctors sometimes call chlamydia the “silent
STD” for this reason. A woman may also transmit
chlamydia to her infant during vaginal childbirth.
Symptoms and Diagnostic PathWhen symptoms are present, they generally appear
within three weeks of exposure. Men may experi-
ence a discharge from the PENISand PAINwith URINA-
TION. Women may experience vaginal discharge
and burning with urination in the early stages of
infection, and later may have pelvic pain, low BACK
PAIN, discomfort or pain with SEXUAL INTERCOURSE,
and vaginal bleeding between periods.
The diagnostic path includes a physical exami-
nation (with PELVIC EXAMINATIONfor women) and
laboratory testing of discharge samples to detect
the presence of C. trachomatis bacteria. Because
chlamydia often does not cause symptoms, diag-
nosis may occur as a consequence of ROUTINE MED-
ICAL EXAMINATION.
Treatment Options and Outlook
Treatment is with oral (by MOUTH) ANTIBIOTIC MED-
ICATIONS. It is important for sex partners to also
receive treatment because when they do not, rein-
fection will occur. Appropriate antibiotic therapy
eliminates the infection. People who receive treat-
ment recover fully. However, scarring and other
damage that occurs because of long-term infection
in a woman is typically permanent, and can result
in INFERTILITY.
Untreated chlamydia has significant conse-
quences for women, about half of whom develop
PELVIC INFLAMMATORY DISEASE(PID). PID is a leading
cause of ECTOPIC PREGNANCYand of infertility. The
infection damages and scars tissue in the FALLOPIAN
TUBES, blocking the pathway by which OVA(eggs)
travel from the OVARIESto the UTERUS. Scarring may
also affect the uterus, preventing implantation in
the earliest stages of PREGNANCY. Untreated
chlamydia increases a woman’s risk for HIV infec-
tion.ANTIBIOTIC MEDICATIONS TO TREAT CHLAMYDIA
amoxicillin azithromycin
doxycycline erythromycin
levofloxacin ofloxacinRisk Factors and Preventive Measures
Nearly all chlamydia infections in adults occur as a
result of vaginal, oral, or anal sex with someone
who has the infection. Women in particular often
are reinfected after they receive treatment but
their sex partners do not. Infants may acquire
chlamydia from their mothers during birth and
may develop chlamydial CONJUNCTIVITIS(infection
of the tissues around the eyes) or PNEUMONIA. Safer
sex practices, such as monogamous relationships
and condom use, are the most effective measures
for preventing chlamydia. Health experts recom-
mend annual chlamydia screening for sexually
active women who are under age 25 or have mul-
tiple sex partners.
See also GENITAL HERPES; GONORRHEA; HUMAN
PAPILLOMAVIRUS(HPV); REITER’S SYNDROME; SCAR; SEX-
UAL HEALTH; SEXUALLY TRANSMITTED DISEASE(STD) PRE-
VENTION; SYPHILIS.cholera An illness resulting from INFECTIONwith
the bacterium Vibrio cholerae. The BACTERIArelease
a toxin in the SMALL INTESTINEthat disrupts the
electrolyte balance, drawing vast amounts of
water into the small intestine and causing sudden,
profuse DIARRHEA. The diarrhea in turn causes
severe DEHYDRATION. The incubation period (time
from exposure to illness) is a few hours to a few
days.
Cholera nearly always occurs in conditions of
poor sanitation and is endemic (constantly pres-
ent) in many areas of the world where commu-
nity sanitation is chronically substandard.
Infection results from drinking water contami-
nated with V. cholerae, eating raw shellfish har-
vested from contaminated water, or eating
uncooked foods rinsed with contaminated water.cholera 317