Epidemiology of fungal keratitis in Queensland, Australia

Importance Fungal keratitis is a rare but sight-threatening ocular infection. The epidemiology varies with geography, in particular climate and demography. Background We present descriptive epidemiology of fungal keratitis in Queensland, a large, geographically heterogenous Australian state. Design Descriptive ecological study. Participants Queensland residents in the period 1996 to January 2016. Methods We searched the state-wide pathology database for positive fungal cultures from corneal scrapings, aqueous humour, vitreous humour or contact lens specimens. Data were analysed by age, sex, climate and location. Cumulative incidence rates were estimated. Main Outcome Measures Episodes of fungal keratitis, from which the abovementioned positive fungal cultures were assumed to originate. Results Two hundred and twenty-one episodes of fungal keratitis in 215 Queensland residents were identified (140 males and 75 females). The median age was 48 years and the modal age range was 25-50 years. Seasonal variation was seen in tropical Queensland. Fusarium (33%) and Aspergillus (13%) were the commonest pathogens. The cumulative incidence per 100 000 population was 4.7, but was significantly higher in rural/regional (5.4) and tropical Queensland (7.9). Conclusions and Relevance In Queensland, fungal keratitis occurs most frequently in males under 50 with increased case identification associated with the hot dry season in tropical Queensland. The sex and age distribution may reflect increased environmental exposure to fungi related to occupation. The higher cumulative incidence in tropical Queensland is in keeping with the rates observed in other tropical regions of the world. Knowledge of the epidemiology of the condition is essential in formulating empirical antifungal regimens in suspected fungal keratitis.