Diseases caused by
Acanthamoeba include
keratitis and
granulomatous amoebic encephalitis (GAE). The latter is often but not always seen in immunosuppressed patients. GAE is caused by the amoebae entering the body through an open wound and then spreading to the brain. The combination of host immune responses and secreted amoebal
proteases causes
massive brain swelling resulting in death in about 95% of those infected.
Granulomatous amoebic encephalitis (GAE) Granulomatous amoebic encephalitis (GAE) is caused by amoebic infection of the central nervous system (CNS). It is characterized by
neurological symptoms including headache, seizures, and mental-status abnormalities. A patient who has contracted this illness usually displays subacute symptoms, including altered mental status, headaches, fever, neck stiffness, seizures, and focal neurological signs (such as cranial nerve palsies and coma), all leading to death within one week to several months. Due to the rarity of this parasite and a lack of knowledge, no good diagnoses or treatments for
Acanthamoeba infection are now known.
Acanthamoeba keratitis cases in the past have resolved from a therapy consisting of atropine and some other drugs with no antimicrobial effects. Recent publications show
atropine to interfere with the protist's
CHRM1 receptor, causing cell death. Infection usually mimics that of bacterial
leptomeningitis, tuberculous
meningitis, or viral encephalitis. The misdiagnosis often leads to erroneous, ineffective treatment. In the case that the
Acanthamoeba is diagnosed correctly, the current treatments, such as
amphotericin B,
rifampicin,
trimethoprim-
sulfamethoxazole,
ketoconazole,
fluconazole,
sulfadiazine, or
albendazole, are only tentatively successful. Correct and timely diagnosis, as well as improved treatment methods and an understanding of the parasite, are important factors in improving the outcome of infection by
Acanthamoeba. A paper published in 2013 has shown substantial effects of some FDA-approved drugs with an
in vitro kill rate above 90%. This condition occurs most often among
contact lens wearers who do not properly disinfect their lenses, exacerbated by a failure to wash hands prior to handling the lenses. Multipurpose contact lens solutions are largely ineffective against
Acanthamoeba, whereas hydrogen peroxide-based solutions have good disinfection characteristics. The first cure of a corneal infection was achieved in 1985 at
Moorfields Eye Hospital. In May 2007, Advanced Medical Optics, manufacturer of Complete Moisture Plus Contact Lens Solution products, issued a voluntary recall of their Complete Moisture Plus solutions. The fear was that contact lens wearers who used their solution were at higher risk of acanthamoebic keratitis than contact lens wearers who used other solutions. The manufacturer recalled the product after the
Centers for Disease Control in the United States found that 21 people had possibly received an
Acanthamoeba infection after using Complete Moisture Plus in the month prior to diagnosis.
As a bacterial reservoir Several species of bacteria that can cause human disease are also able to infect and replicate within
Acanthamoeba species. For some of these bacteria, replication inside
Acanthamoeba has been associated with enhanced growth in
macrophages, and increased resistance to some antibiotics. Furthermore, due to the high prevalence of
Acanthamoeba in the environment, these amoebae have been proposed to serve as an environmental reservoir for some human pathogens. ==Ecology==