Giardia lamblia protozoa, SEM. © Science Photo Library

Giardia lamblia is a tiny parasite that produces durable cysts. It can live in the bowels of humans and animals and is often found in contaminated surface water. 

People may be asymptomatic or show symptoms 3 to 25 days after infection such as:

  • diarrhea
  • stomach pain
  • bloating
  • tiredness
  • trouble absorbing important nutrients

Transmission occurs through contact with infected patients or exposure to contaminated surfaces, food or water. As a result, the infection is more likely to spread in settings such as private homes and day care centers.  Sexual transmission is also possible. Cases among hikers or backpackers in the wilderness areas are common, and waterborne outbreaks due to swimming in contaminated bathing sites, including pools, or inadequate treatment of drinking water are also common.

Disease data from ECDC Surveillance Atlas - giardiasis

The Surveillance Atlas of Infectious Diseases is a tool that interacts with the latest available data about a number of infectious diseases. The interface allows users to interact and manipulate the data to produce a variety of tables and maps.​​