So you may have trouble pinpointing exactly when you became infected. These symptoms can continue for up to four months or longer. But most infected people never develop symptoms, or get over the infection in one to four weeks without treatment. On the other hand, some people develop a chronic infection, with or without symptoms. Chronic symptoms are very dangerous for those with compromised immune systems.
Giardia infection can be tricky to diagnose, since the cysts are excreted only periodically.
You may need to give stool samples on three different days. It is treated with prescription antiparasitic drugs, which are effective, but can have unpleasant side effects. Using only chlorine or iodine won't protect you from giardia cysts. When traveling in the developing world or anywhere sanitation and hygiene are poor, take precautions. Don't drink tap water unless you boil it, don't use ice cubes, and don't brush your teeth with tap water.