Infection is acquired by ingestion of water or food contaminated with the parasite.
Infection can be asymptomatic or be manifested by such symptoms as watery diarrhea, loss of appetite, weight loss, bloating, increased gas, stomach cramps, nausea, vomiting, fatigue, muscle aches, and low-grade fever. Some persons first notice flu-like symptoms. If untreated, the illness can last for weeks to months. Occurrence Infection can be acquired worldwide. Risk for Travelers Travelers to developing countries may be at increased risk for this infection, and the risk may vary with season.