Routine water chlorination is ineffective in destroying Giardia . Giardiasis in Animals Infected animals usually show no signs of disease. Diarrhea may occur in young animals. The animal may recover from disease without treatment. Fecal shedding of the agent may occur with or without signs of disease.
Many infected people show no signs of illness.
Humans that show symptoms of illness will do so 1-3 weeks after infection. Symptoms include diarrhea and abdominal pain. Less often there is nausea and vomiting. The disease usually lasts 3-4 days. Some people become chronically infected with episodes of recurring symptoms.