It works by decreasing the ability of the immune system to respond to infection. If you cat comes in contact with other cats, we strongly recommend you protect your cat against feline leukemia. Like leukemia, FIP is passed from cat to cat. It is highly contagious, always fatal disease there is NO cure. Giardia infections can cause significant gastrointestinal disease including diarrhea, weight loss and poor weight gain despite normal appetite.
Humans report intense abdominal pain and cramping from giardiasis.