Giardia in Humans
Giardia is a microscopic parasite responsible for the diarrhea-related illness giardiasis. Also known as Giardia intestinalis or Giardia lamblia, this organism begins to multiply within the intestines after a person becomes infected. Transmission can occur when a person accidentally swallows the parasite, such as when eating contaminated food or drinking contaminated water.
Symptoms can occur approximately one to two weeks after infection and can include diarrhea, gas, and stomach cramps, among others. Weight loss and dehydration can occur as a result of giardiasis. Treatment typically involves taking a common prescription medication.
(For more details on symptoms of giardiasis, treatment options, and different ways in which humans can become infected with this parasite, click Giardia.)