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Epidemiology and Risk Factors
Acanthamoeba keratitis primarily affects otherwise healthy people, most of whom wear contact lenses. In the United States, an estimated 85% of cases occur in contact lens users. The incidence of the disease in the U.S. is approximately one to two cases per million contact lens users. Contact lens wearers who practice proper lens care and non-contact lens wearers can still develop the infection. However, there are several practices among contact lens users that increase the risk of getting Acanthamoeba keratitis including:
- Improper storage and handling of lenses
- Improper disinfection of lenses (such as using tap water or homemade solutions to clean the lenses)
- Swimming, using a hot tub, or showering while wearing lenses
- Coming into contact with contaminated water
- Having a history of trauma to the cornea
No known cases of Acanthamoeba keratitis being spread from one person to another have been reported.
Granulomatous Amebic Encephalitis (GAE) and disseminated infection are very rare forms of Acanthamoeba infection and primarily affect people with compromised immune systems. While unusual, disseminated infection can also affect immunocompetent children and adults. Conditions that may increase a patient’s risk for GAE and disseminated infection include:
- AIDS
- Organ/Tissue transplant
- Steroids or excessive use of antibiotics
- Diabetes Mellitus
- Cancer
- Disorders in which white blood cells in the lymphatic tissue are over-produced or abnormal
- Disorders in which blood cells or blood clotting mechanisms do not function properly or are abnormal
- Liver cirrhosis
- Lupus