LINK / CITE ADD TO WORD LIST. adjective. The definition of harmful is something that causes damage or is able to be hurtful. A chemical that causes you to become sick is an example of a chemical that would be described as harmful. causing or able to cause harm; hurtful. adjective.
The most common way to become infected with giardia is after swallowing contaminated water. Giardia parasites are found in lakes, ponds, rivers and streams worldwide, as well as in municipal water supplies, wells, cisterns, swimming pools, water parks and spas. Ground and surface water can become contaminated from agricultural runoff, wastewater discharge or animal feces.
Cysts of Giardia are present in the feces of infected persons. Thus, the infection is spread from person to person by contamination of food with feces, or by direct fecal-oral contamination.Cysts also survive in water, for example in fresh water lakes and streams.iardia lamblia exists in two forms, an active form called a trophozoite, and an inactive form called a cyst. The active trophozoite attaches to the lining of the small intestine with a sucker and is responsible for causing the signs and symptoms of giardiasis.