Epidemiology

Giardiasis occurs worldwide, but it is common in the tropics and sub-tropics in areas where sewage is disposed of ineffectively and water supplies are contaminated (1):

• an estimated 280 million infections in humans annually
• highest burden occurs in children living in low- and middle-income countries (LMIC) and Giardia exposure is commonly associated with poor socioeconomic conditions
• G. lamblia (aka G. duodenalis and G. intestinalis) is one of the most common intestinal parasitic infections, and it is transmitted through the fecal-oral route by waterborne and food sources

Giardiasis is fairly common in urban populations in south and eastern Europe, particularly among children, the elderly and homosexuals. Water-borne epidemics have also occurred in towns in the USA and Canada.

Reference:

1. Gutiérrez L, Bartelt L. Current Understanding of Giardia lamblia and Pathogenesis of Stunting and Cognitive Deficits in Children from Low- and Middle-Income Countries. Curr Trop Med Rep. 2024 Mar;11(1):28-39.