What is giardiasis?

Causes and Symptoms

The parasite
Giardia lamblia, which causes giardiasis, is a protozoan acquired through the ingestion of contaminated food or water. This organism can also be spread by person-to-person contact involving fecal contamination. It is the most frequent parasite acquired by children in day care centers and preschools.

After exposure, the incubation period before the onset of symptoms is one to two weeks. After infection, only 25 to 50 percent of affected individuals become symptomatic. The disease is characterized by abdominal pain
, cramps, flatulence, weight loss, and diarrhea, which in many cases may be chronic (of a duration longer than fifteen days).

Treatment and Therapy

Some cases of giardiasis are self-limited. The treatment of choice for giardiasis in the United States is a single oral dose of tinidazole. Metronidazole and nitazoxanide are alternative oral medications, but require multiple doses over several days. Furazolidone and metronidazole are equally efficacious; the first may be more practical in children because of its availability in liquid form.

Giardiasis can be prevented by strict hand-washing, especially in those individuals who are in close contact with patients with diarrhea or children in diapers at day care centers. Another important consideration in the prevention of giardiasis resides in the purification of drinking water, which can be achieved through boiling or chemical decontamination. It has been demonstrated that breast-feeding protects infants against symptomatic infection.

Perspective and Prospects

G. lamblia was first observed by microscopist Antoni van Leeuwenhoek in 1675. It was once considered a harmless organism, but its pathogenic role was clearly established in the 1960s. This parasite is one of the most common protozoans able to infect humans.

Bibliography:

Alan, Rick, and Michael Woods. "Giardiasis." Health Library, November 2012.

Berger, Stephen A., and John S. Marr. Human Parasitic Diseases Sourcebook. Sudbury, Mass.: Jones and Bartlett, 2006.

Despommier, Dickson D., et al. Parasitic Diseases. 5th ed. New York: Apple Tree, 2006.

"Giardia Infection (Giardiasis)." Mayo Clinic, November 14, 2012.

"Giardiasis Frequently Asked Questions." Centers for Disease Control and Prevention, July 11, 2012.

Hill, David R., and Theodore E. Nash. “Giardia lamblia.” In Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, edited by Gerald L. Mandell, John F. Bennett, and Raphael Dolin. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.

Roberts, Larry S., and John Janovy, Jr., eds. Gerald D. Schmidt and Larry S. Roberts’ Foundations of Parasitology. 7th ed. Boston: McGraw-Hill Higher Education, 2005.