Scientific Name: Giardia lamblia
Morphological Characteristics
G. lamblia is a flagellated unicellular eukaryotic organism. The sucking disc allows the parasite to attach to the host.
Identification Methods
The trophozoite and cyst phases can be found in stool samples using microscopy. An entererotest can also be used. In an entererotest the host swallows a thread with a capsule on it and attached to a string. The thread travels through the stomach, so when it is extracted it is tested for G. lamblia using a centrifuge to separate from a saline solution.
LIFE CYCLE
- Giardia cysts contaminate food, water, and surfaces. A person swallows the cysts in some manner
- The cysts pass to the small intestine. Each cyst releases trophozoites which feed off of and absorb nutrients from the host
- Giardia split into 2 through binary fission
- The trophozoites move to the colon and transform back to the cyst form.
- The cysts pass in the stool of the infected person. The cysts can survive for many months in cold water or soil
HOST INFORMATION
- No intermediate hosts
- Children are at higher risk
- backpackers/campers are at risk of drinking contaminated water if untreated
- Travelers to areas with poor sanitation
- Anywhere where contaminated feces could contaminate another surface
GEOGRAPHICAL DISTRIBUTION
This parasite is distributed worldwide but is most common in the tropics and subtropics.
SOURCES
https://www.cdc.gov/parasites/giardia/pathogen.html
https://www.who.int/ith/diseases/giardiasis/en/