Other drugs may be needed as supplemental therapy should diarrhea and dehydration occur. Another antiparasitic drug, fenbendazole, is being investigated as a potentially useful treatment. It appears to be very effective and may be used in cats with refractory diarrhea as a means of diagnosing and treating Giardia. The prognosis is good in most cases. Debilitated or geriatric animals and those with incompetent immune systems are at increased risk for death.
Giardiasis is the most common intestinal parasitic infection of man.
In the past, it has been assumed that cats and dogs served as the source of infection for humans. Current research is beginning to indicate that perhaps cats and dogs do not serve as an important reservoir of the disease for man. In cities which do not have water treatment facilities with a sand filtration system, Giardia may not be removed from the drinking water. Nevertheless, until the issue of transmission is resolved, caution is advisable when a pet has been diagnosed with giardiasis. For environmental disinfection, a cup of chlorine bleach in a gallon of water is effective.