![Left: G. intestinalis trophozoites in Kohn stain. Center: G. intestinalis cyst stained with trichrome. Right: G. intestinalis in in vitro culture, from a quality control slide.](https://webarchive.library.unt.edu/web/20121017105004im_/http://www.cdc.gov/parasites/images/giardia/home_page_image_giardia.jpg)
Giardia is a microscopic parasite that causes the diarrheal illness known as giardiasis. Giardia (also known as Giardia intestinalis, Giardia lamblia, or Giardia duodenalis) is found on surfaces or in soil, food, or water that has been contaminated with feces (poop) from infected humans or animals.
Giardia is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it tolerant to chlorine disinfection. While the parasite can be spread in different ways, water (drinking water and recreational water) is the most common method of transmission.
Image: Left: G. intestinalis trophozoites in Kohn stain. Center: G. intestinalis cyst stained with trichrome. Right: G. intestinalis in in vitro culture, from a quality control slide. Credit: DPDx
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- General Information Most common questions answered...
- Epidemiology & Risk Factors Who gets it and how...
- Biology Stages of parasite development...
- Disease Signs and symptoms of the disease...
- Diagnosis Tests for infection...
- Treatment Medication and steps to take...
- Prevention & Control How to stay healthy or get better...
- Resources for Health Professionals What you need to know...
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