may recommend CESAREAN SECTION(surgical deliv-
ery) for women whose infections are active
(symptomatic) near the time of delivery to pre-
vent this.
Risk Factors and Preventive MeasuresBecause HSV-2 infection is so prevalent, all sexu-
ally active people are at risk for genital herpes.
Uninfected people who are in monogamous rela-
tionships with uninfected sexual partners have the
lowest risk for infection; uninfected people who
have multiple sexual partners or who are in rela-
tionships with sexual partners who have genital
herpes have the highest risk for infection. At pres-
ent the most effective means of prevention among
sexually active adults is abstinence during out-
breaks and barrier protection such as latex con-
doms during all sexual activity. Barrier protection
is not absolute, however, as the HSV-2 virus may
infect nerve cells at the skin’s surface that the con-
dom does not cover.
The antiviral medication valacyclovir signifi-
cantly reduces viral shedding, slowing but not
entirely preventing transmission of genital herpes.
This preventive measure is most effective in
monogamous relationships in which one person
has HSV-2 and the other does not. Clinical studies
are under way to evaluate a vaccine for genital
herpes.
See also CHLAMYDIA; COLD SORE; CONTRACEPTION;
GONORRHEA; HUMAN PAPILLOMAVIRUS (HPV); LY M P H
NODE; OCULAR HERPES; SEXUAL HEALTH; SEXUALLY
TRANSMITTED DISEASE (STD) PREVENTION; SEXUALLY
TRANSMITTED DISEASES(STDS); SYPHILIS.
giardiasis An illness resulting from INFECTION
with the protozoan Giardia lamblia(also called Gia-
rdia intestinalis). Giardia are abundant in fresh
water throughout the United States; infection
occurs through drinking contaminated water. The
PROTOZOAinfect the SMALL INTESTINEof humans and
animals and can survive for extended periods
without a host. The most common means of infec-
tion is through swallowing water in recreational
settings, such as lakes, rivers, and streams. Foun-
tains, swimming pools, and hot tubs that lack
proper chlorination also may harbor Giardia. Giar-
diasis also spreads through fecal contamination by
direct contact, such as by changing diapers, and
can occur as aFOODBORNE ILLNESSspread through
poor FOOD SAFETYpractices.
Symptoms develop after an incubation period
of 7 to 10 days and include DIARRHEA, excessive
FLATULENCE(gas), abdominal discomfort, and NAU-
SEA. The diarrhea is watery and has a greasy
appearance. Some people also experience fatigue,
loss of APPETITE, and rapid weight loss. It is also
possible to have giardiasis and have no symptoms.
Stool samples examined under the microscope
typically contain both cysts and trophozoites, the
immature and mature forms, respectively, of the
Giardia. Treatment is ANTIBIOTIC MEDICATIONSand
ANTIFUNGAL MEDICATIONS. The course of illness runs
four to six weeks with treatment, after which
most people recover without complications or
residual consequences. Without treatment giardia-
sis may persist for six to eight weeks, with gradual
though complete recovery.MEDICATIONS TO TREAT GIARDIASIS
albendazole furazolidone
metronidazole nitazoxanide
paromomycin tinidazoleSee also AMEBIASIS; BABESIOSIS; DRINKING WATER
STANDARDS.gonorrhea A sexually transmitted disease (STD)
resulting from INFECTIONwith the bacterium Neisse-
ria gonorrhoeae. N. gonorrhoeae infects 350,000
Americans each year, though public health offi-
cials believe another 350,000 people have gonor-
rhea that goes undiagnosed because they do not
know they are infected. Gonorrhea is highly con-
tagious and passes among sexual partners through
vaginal intercourse, anal intercourse, or oral sex.
People who have multiple sex partners have
increased risk for gonorrhea as well as other STDs.
Gonorrhea is a public health concern of great
magnitude worldwide because a number of strains
of N. gonorrhoeae have become resistant to the
ANTIBIOTIC MEDICATIONSused to treat the infection.Symptoms and Diagnostic Path
Gonorrhea has a 2- to 10-day INCUBATION PERIOD
(time from exposure to symptoms) though often
causes no symptoms, especially in women. Symp-
toms that do occur tend to be generalized andgonorrhea 329