Acanthamoeba is a free-living protozoa that is found in soil and water. It is commonly found in drinking water, sewage, soil, and ventilation systems. It enters the body by inhalation or through the nostrils from swimming. In rare cases, the organism is able to cause infections of the brain, eyes, skin, lungs and sinuses. Immune compromised individuals are also susceptible.
Types of infections
There are three types of human infection caused by the organism acanthamoeba, according to the Centers for Disease Control and Prevention. Disseminated infection affects immune-compromised individuals and affects the lungs, skin, sinuses and other organs. Keratitis, or eye infection, is also very common and can lead to visual impairment or blindness. The amoeba invades the outer covering of the eye called the cornea, and causes damage to the eye. The most serious of infection is granulomatous amebic encephalitis, where the organism infects the brain and spinal cord. The result is inflammation of the brain that may be fatal.
Risk factors
Certain factors put individuals at a higher risk of acanthamoeba infection. Risks of keratitis include swimming or showering while wearing contact lenses, contact with contaminated water, trauma to the cornea, and carelessness while storing and disinfecting contact lenses, according to the U.S. Food and Drug Administration. Risk factors for disseminated infection and encephalitis include conditions such as liver cirrhosis, diabetes, AIDS, cancer, lupus, organ transplant, blood clotting and white blood cell disorders, and use of excessive antibiotics and steroids.
Diagnosis
Diagnosis of acanthamoeba infection depends on the site of infection, according to the Centers for Disease Control and Prevention. It is usually difficult to diagnose disseminated infection and encephalitis because these conditions, when present, indicate advanced infection. Disseminated infection involves taking a biopsy of the affected site. The biopsy is then observed under a microscope for damage and presence of the organism. Encephalitis is diagnosed though brain scans, spinal taps, and biopsies. Keratitis is diagnosed by observation under a microscope or culturing the organism in order to identify it.
Treatment
Encephalitis or brain infection has no treatment and is usually fatal due to the inflammation and damage that occurs to the brain. Disseminated infection is usually treated depending on the area infected and is usually successful. Keratitis is treated with propamidine iIsothionate, microconazole and ketoconazole. A procedure called penetrating keratoplasty may be needed to restore vision. The procedure involves using a graft of the cornea to restore vision, according to the U.S. Food and Drug Administration.
Prevention
Prevention of disseminated and encephalitis infections may be difficult, as the organism is found throughout nature. It is important for immune compromised individuals to consult with doctors about their activities in order to stay safe. Prevention of keratitis includes proper disinfection and care of contact lenses and storage cases, according to manufacturer instructions. Wearing contact lenses during swimming, showering and all water activities should be avoided and high-risk individuals should go for regular eye exams.
