Giardia

Giardia are a group of flagellate protozoans (single-celled, microscopic parasites) which grow in the intestines of infected humans or animals. Giardia cause diarrhoeal disease in humans.

The disease can be transmitted by direct contact with infected animals or humans, or by consumption of water, food or beverages contaminated by the faeces of infected animals or humans. People may also be infected by swimming in contaminated water (for example in lakes or rivers).

Many cases are associated with recent foreign travel.

Giardia lamblia (Image: CDC / Janice Carr)