Giardiasis epidemiology and demographics

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yazan Daaboul, M.D.; Serge Korjian M.D.

Giardiasis is a worldwide infection. It is the most common cause of parasitic diarrhea with a prevalence that may be as high as 20% to 40% in settings of poor sanitation. In the USA, the incidence of giardiasis is thought to be decreasing from 20 to 25 cases per 100,000 individuals between 1990 and 1998 to approximately 4 to 5 cases per 100,000 individuals in 2012. Children, particularly < 5 years of age, are more frequently affected with giardiasis than adults. There is no gender or racial predilection for the development of giardiasis.

• Giardiasis is a worldwide infection. It is the most common cause of parasitic diarrhea.^[1]
• In the USA, the incidence of giardiasis is thought to be decreaesing. In 2012, the incidence of giardiasis was approximately 4 to 5 cases per 100,000 individuals in the USA, compared with 20 to 25 cases per 100,000 individuals between 1990 and 1998.^[2][3]
• The prevalence of giardiasis is highly variable. In settings with poor sanitation, the prevalence of giardiasis may be as high as 40%.^[1]

• Children, particularly < 5 years of age, are more frequently affected with giardiasis than adults.

• There is no gender predilection for the development of giardiasis.

• There is no racial predilection for the development of giardiasis.

• In developed countries, the incidence of giardiasis is decreasing.
• The decrease is attributed to improved sanitation and available resources.

• The majority of cases of giardiasis occur in developing countries, where the prevalence may be as high as 20% to 40% in settings of poor sanitation.^[1]

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