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8698

PHIL Image 8698

ID#:8698
Description:This scanning electron micrograph (SEM) revealed some of the external ultrastructural details displayed by a flagellated Giardia lamblia protozoan parasite. G. lamblia is the organism responsible for causing the diarrheal disease "giardiasis". Once an animal or person has been infected with this protozoan, the parasite lives in the intestine, and is passed in the stool. Because the parasite is protected by an outer shell, it can survive outside the body, and in the environment for long periods of time.

Cysts are resistant forms and are responsible for transmission of giardiasis. Both cysts and trophozoites can be found in the feces (diagnostic stages). The cysts are hardy and can survive several months in cold water. Infection occurs by the ingestion of cysts in contaminated water, food, or by the fecal-oral route (hands or fomites). In the small intestine, excystation releases trophozoites (each cyst produces two trophozoites). Trophozoites multiply by longitudinal binary fission, remaining in the lumen of the proximal small bowel where they can be free or attached to the mucosa by a ventral sucking disk. Encystation occurs as the parasites transit toward the colon. The cyst is the stage found most commonly in non-diarrheal feces. Because the cysts are infectious when passed in the stool or shortly afterward, person-to-person transmission is possible. While animals are infected with Giardia, their importance as a reservoir is unclear.

High Resolution:Right click here and select "Save Target As..." for hi-resolution image (3.46 MB)
Content Providers(s):CDC/ Janice Haney Carr
Creation Date:
Photo Credit:Janice Haney Carr
Links:
  • CDC - Nat. Center for Infectious Diseases; Div. of Parasitic Diseases: Giardiasis Fact Sheet
  • CDC - Div. of Parasitic Diseases: Giardiasis Fact Sheet
    Categories:
    CDC Organization

    MeSH
    tree picture Analytical, Diagnostic and Therapeutic Techniques and Equipment
    tree picture tree picture Investigative Techniques
    tree picturetree picture tree picture Microscopy
    tree picturetree picturetree picture tree picture Microscopy, Electron
    tree picturetree picturetree picturetree picture tree picture Microscopy, Electron, Scanning
    tree picturetree picturetree picture tree picture Photomicrography
    tree picture Diseases
    tree picture tree picture Digestive System Diseases
    tree picturetree picture tree picture Gastrointestinal Diseases
    tree picturetree picturetree picture tree picture Intestinal Diseases
    tree picturetree picturetree picturetree picture tree picture Intestinal Diseases, Parasitic
    tree picturetree picturetree picturetree picturetree picture tree picture Giardiasis
    tree picture tree picture Parasitic Diseases
    tree picturetree picture tree picture Intestinal Diseases, Parasitic
    tree picturetree picturetree picture tree picture Giardiasis
    tree picturetree picture tree picture Protozoan Infections
    tree picturetree picturetree picture tree picture Sarcomastigophora Infections
    tree picturetree picturetree picturetree picture tree picture Mastigophora Infections
    tree picturetree picturetree picturetree picturetree picture tree picture Giardiasis
    tree picture Organisms
    tree picture tree picture Animals
    tree picturetree picture tree picture Invertebrates
    tree picturetree picturetree picture tree picture Protozoa
    tree picturetree picturetree picturetree picture tree picture Sarcomastigophora
    tree picturetree picturetree picturetree picturetree picture tree picture Mastigophora
    tree picturetree picturetree picturetree picturetree picturetree picture tree picture Zoomastigophora
    tree picturetree picturetree picturetree picturetree picturetree picturetree picture tree picture Diplomonadida
    tree picturetree picturetree picturetree picturetree picturetree picturetree picturetree picture tree picture Giardia
    tree picturetree picturetree picturetree picturetree picturetree picturetree picturetree picturetree picture tree picture Giardia lamblia
    Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.
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