While the vast majority of cases of Acanthamoeba keratitis occur in contact lens wearers, there have been many cases of Acanthamoeba described in those who do not wear contact lenses, especially outside the United States.[15][16] In non-contact lens users, the greatest risks for developing Acanthamoeba infection are trauma and exposure to contaminated water.[17] Further predisposing factors include contaminated home water supply, and low socioeconomic status. Infection is also more commonly seen in tropical or sub-tropical climates.[17]