ORGANIZATIONS
American College of Gastroenterology. P.O. Box 342260
Bethesda, MD 20827-2260. Telephone: (301) 263-9000.
Website:<http://www.acg.gi.org>
American Gastroenterological Association. 4930 Del Ray
Avenue, Bethesda, MD 20814, Telephone: (301)
654-2089. Website:<:http://www.gastro.org>
National Digestive Diseases Information Clearinghouse
(NDDIC). 2 Information Way, Bethesda, MD 20892-- Telephone: (800) 891-5389. Fax: (703) 738-4929.
Website:http://digestive.niddk.nih.gov
National Heartburn Alliance. Website:<http://www.heart
burnalliance .org>
OTHER
Fisichella, P. Marco. ‘‘Gastroesophageal Reflux Disease.’’
eMedicine.com, February 8, 2007.http://www.
emedicine.com/med/topic857.htm
Medline Plus. ‘‘.’’ U. S. National Library of Medicine,
March 27, 2007.http://www.nlm.nih/gov/medline
plus/gerd.html
National Digestive Diseases Information Clearinghouse
(NDDIC). ‘‘Heartburn, Hiatal Hernia, and Gastroeso-
phageal Reflux Disease (GERD).’’ June 2003.http://
digestive.niddk.nih.gov/diseases/pubs/gerd/
index.htm
American College of Gastroenterology. ‘‘Understanding
GERD.’’ 2006.http://www.acg.gi.org/patients/gerd/
word.asp
Simic, P. John and Vincent W. Yang ‘‘Reflux Disease
(GERD).’’ eMedicineHealth.com, August 10, 2005.
http://www.emedicinehealth.com/reflux_disease_
gerd/article_em.htm
Tish Davidson, A.M.GERDseeGastroesophageal reflux disease
Giardiasis
Definition
Giardiasis is a communicable gastrointestinal dis-
ease characterized by acute diarrhea. It is caused by a
parasite,Giardia lamblia, also known asGiardia intes-
tinalis. Giardiasis is the most common water-borne
infection of the human intestine worldwide, affecting
as many as 200 million people each year. According to
the Centers for Disease Control and Prevention
(CDC), there were 90 major community outbreaks of
giardiasis in the United States between 1964 and 1984,
and 34 major outbreaks since 1985.
The organism that causes giardiasis,G. lamblia,is
a protozoan, a single-celled organism formerly classi-fied as a member of the animal kingdom. It is a pear-
shaped parasite with four flagella, which are long
whip-like extensions of the cell that allow the organism
to move. It was first seen under a microscope by the
Dutch lens maker Antony van Leeuwenhoek in the
17th century.G. lambliawas found in human stool
samples in 1859 by a Czech physician named Lambl,
but was not identified as the cause of giardiasis until
the 1970s. It was given its present name in 1915 to
honor Alfred Giard, a French biologist, as well as Dr.
Lambl.Origins
Dietary treatment of patients with giardiasis has
been a gradual process, dependent on better under-
standing of the causes of the disease as well as the
development of nutritionally adequate rehydration
solutions and anti-infective medications. A large part
of dietary therapy for giardiasis, in fact, consists of
measures to prevent the spread of the disease, not just
to treat the symptoms after they appear.Description
Life cycle of G. lamblia
In order to understand the symptoms, treatment,
and prevention of giardiasis, it is helpful to understand
the life cycle ofG. lamblia. The parasite that causes
giardiasis has a simple two-stage life cycle that does
not require an intermediate host; it can be spread
directly among human beings. The cycle begins when
a person swallows as few as 10 to 15 cysts ofG. lamblia.
The cyst is a protective shell that the organism forms
around itself that enables it to survive outside a human
or animal host. The cysts ofG. lambliaare smooth-Giardiasis is a diarrheal illness caused by a one-celled,
microscopic parasite, Giardia intestinalis (also known as
Giardia lamblia).(Dr. George Wilder/Visuals Unlimited/Getty
Images. Reproduced by permission.)Giardiasis