Last edited 02/2020

Transmission occurs via the ingestion of cysts in contaminated food and water. The infective dose may be as low as 10 cysts, though studies have shown that 100 cysts are required to produce a 50% infection rate.

  • Faecal-oral spread, by direct or indirect contact with the faeces of infected people or animals:
    • person-to-person spread is common, particularly within families/households
    • waterborne, including swimming in contaminated recreational water
    • direct contact with infected animals
    • foodborne transmission
    • sexual transmission, particularly amongst MSM
    • direct contact with infected animals (rare)

  • Outbreaks have been associated with infected food handlers, drinking water and swimming pools