BB30052 Scientific CommunicationThe pathophysiology of Acanthamoeba Keratitis

Junho Jung30th April 2007

Introduction What is Acanthamoeba?

One of the most common protozoa in soil, and also frequently found in fresh water

Most species are free-living bacterivores some are opportunists that can cause

infections in humans and other animal Relatively rare disease. However in 2002, between 17 and 21 Acanthamoeba

infection cases per million contact-lens wearers reported in UK.

Acanthamoeba as a human pathogen Acanthamoeba causes amoebic keratitis

and encephalitis Eye infection has been associated with

contact lens use Also enter the skin through a wound or

nostrils. Amoebas can travel to the lungs and through the bloodstream to central nerve system, cause fatal infection called granulomatous amebic encephalitis (GAE).

Symptoms of Acanthamoeba infection A corneal ulcer may result from

exposures. This could be sight-threatening without proper treatment.

Acanthamoeba spp. can cause skin lesions and a systemic (whole body) infection.

GAE Patients may suffer with headaches, stiff neck, nausea, vomiting, tiredness, confusion, lack of attention, loss of balance and bodily control, seizures, and hallucinations.

The pathogenic cascade of Acanthamoeba keratitis Attachment Destruction of epithelium and

upregulation of MMPs Breachment of Bowman’s

membrane Degradation of stroma Radialneuritis

Treatment for infection with Acanthamoeba Eye and skin infections are generally

treatable. Treatment is most effective when the diagnosis is made promptly.

Because the cyst may form, and can be highly resistant to therapy, a combination of agents is generally used.

Although most cases of brain (CNS) infection with Acanthamoeba have been fatal, a few have recovered from the infection with proper treatment.

Acanthamoeba and MRSA Recent findings from the University

of Bath demonstrate that MRSA can infect and replicate inside of Acanthamoeba polyphaga;

Since A. polyphaga can form cysts, cysts infected with MRSA can act as a mode of airborne dispersal for MRSA.

Concluding remarks A better understanding of the pathogenic

cascade of Acanthamoeba keratitis could lead to improved clinical treatment of this and other amebic infections.

Might be possible to develop Multivalent mucosal vaccines that induce multiple secretory IgA antibodies that target the lectin-binding molecules on the surface of the amoeba and the proteases that are released during invasion of the mucosal surface.