Management of giardiasis.

Giardia lamblia is the most common cause of infectious diarrhea in the world. In the United States, it has been cited as the cause of several epidemics of waterborne disease. The organism has cyst and trophozoite forms, but only the cyst can exist outside the host. The gastrointestinal symptoms of giardiasis are usually self-limited, but chronic cases may occur. Patient education helps reduce public anxiety during an epidemic.