Acanthamoeba keratitis cluster: an increase in Acanthamoeba keratitis in Australia

Abstract

Background: This study was undertaken in response to an increase in the number of patients treated for Acanthamoeba keratitis at a tertiary referral hospital in Brisbane, Australia. Incidence and patient characteristics were investigated over a 4-year period.

Methods: A retrospective consecutive case series study was performed on patients with Acanthamoeba keratitis presenting to the Princess Alexandra Hospital between January 2003 and March 2007.

Results: Nine cases of Acanthamoeba keratitis were identified over 12 months from March 2006 to March 2007 compared with four cases over the previous 37 months from January 2003 to February 2006. This was an increase from 0.07 cases per 1000 outpatient visits to 0.42 per 1000 (P = 0.003). Of the 13 cases, 11 patients used soft contact lenses of which two used monthly extended overnight wear silicone hydrogel lenses. Of the five patients who specified the type of contact lens solution they had used, three reported using AMO Complete Moistureplus Multipurpose solution, one reported using the AMO Complete Comfortplus Multipurpose solution and one was unsure which type of AMO Complete solution they were using.

Conclusions: There has been a significant increase in incidence of cases of Acanthamoeba keratitis presenting to our institution. The type of contact lens solution and the use of silicon hydrogel lenses combined with extended overnight wear may play a role; however, the significance is unclear given the small numbers for analysis. Further study of incidence and patient characteristics is warranted to identify risk factors and causes for the rising incidence.