Microsporidial Keratitis in Patients with Hot Springs Exposure

This retrospective study included 10 eyes of 9 patients diagnosed with microsporidial keratitis. All of themwere known to con-tract this disease after taking baths in hot springs. The disease was diagnosed based on detecting microsporidia in corneal scrap-ings using Gram stain and the modified Kinyoun’s acid-fast stain. The specimens from the last six patients were subjected to PCR and then sequencing. All of them revealed that the microorganism identified has a high similarity to Vittaforma corneae. Repeated debridement of the epithelial lesions successfully eradicated the microsporidial infection in all nine patients. Microsporidia are tiny, obligate intracellular eukaryotic pro-tozoan parasites that can produce infective spores. The or-ganism iswidespread in the environment (36), and it is considered a waterborne pathogen (9, 16, 31). Many species of microsporidia are pathogenic to animals (7, 28), and these are also confirmed to cause opportunistic infection in humans (36). These organisms cause infection not only of human digestive tracts but also of many other organs, including eyes (25, 36). In past reports, mi-crosporidial keratitis usually was found to occur as epithelial ker-atitis in patients with AIDS (1, 11, 22–24, 37) and as stromal dis-ease in immunocompetent individuals (34–35). Recently, it has been found to manifest as keratoconjunctivitis with involvement of the corneal epitheliummainly in healthy individuals (4, 13, 21, 30, 32), and it is considered an emerging ocular disease (21). To date, a number of studies were reported on the predisposing fac-tors formicrosporidial keratitis in immunocompetent individual