Symptoms include diarrhea, stomach cramps, bloating, severe flatulence, weight loss and fatigue. Bowel movements may be loose, mucousy and greasy. One in every 25 people carries giardia without showing any symptoms. Symptoms appear within 5 to 25 days after contact, however 7 to 10 days are the most common. Diarrhea usually lasts several weeks, but occasionally becomes chronic.
Giardiasis occurs worldwide and children are infected more often than adults are.
It is usually spread through fecally contaminated water supplies, or from touching human or animal feces. People should be cautioned against drinking untreated surface water like water from rivers, streams, springs and lakes. Swallowing water while swimming in any of these supplies also puts you at risk of acquiring a giardia infection. The parasite can also be spread from person to person through hand to mouth contact or unwashed hands touching items that will go into the mouth. It can spread quickly through a family when one member becomes infected or at daycare centres where children have close contact with each other.