Microsporidial Keratitis in Patients with Hot Springs Exposure

Abstract

This retrospective study included 10 eyes of 9 patients diagnosed with microsporidial keratitis. All of them were known to contract this disease after taking baths in hot springs. The disease was diagnosed based on detecting microsporidia in corneal scrapings 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.

Outbreak of microsporidial keratoconjunctivitis with rugby sport due to soil exposure

“…20 Recent report in Taiwan had suggested nine patients contracting the disease through in hot spring baths. 17 In Singapore, Loh et al 16 reported 124 cases of microsporidial keratitis. He found a strong correlation of soil/mud exposure in 62 cases (50%) from outdoor activities, including soccer, golf, and trail biking, especially after rainfall.…”

“…14,16,17 The diagnosis can be made by detecting microsporidia in the corneal scraping using CFW, modified trichrome, or modified acid-fast stain. 18 Electron microscopy is useful for definitive diagnosis.…”

Microsporidia

“…The detection of microsporidia in groundwater samples indicates that there may be the potential for subsurface transport of these parasites (Dowd et al, 1998). A recent study in Taiwan showed correlation between taking baths in hot springs and the incidence of microsporidial keratitis in nine patients infected with V. corneae, but whether there are factors present in the hot springs that make attendees more susceptible to microsporidial invasion still requires further investigation (Fan et al, 2012).…”

“…These disinfectants, however, are rarely used for hot springs due to the unpleasant odor. There are other methods that can be used to keep the hot springs clean, including frequent recycling of the spring water through filters, reheating, photoirradiation, and treating with hydrogen peroxide (Fan et al, 2012). Because the microsporidian spores like V. corneae were measured at 3.3 by 1.4 μm, recycling of the spring water through filters with pore sizes larger than 2 μm cannot remove the parasite (Fan et al, 2012).…”

Microsporidial Keratitis

“…Other risk factors are trauma, dust particles, contact lens, insect bites, bathing in unclean river waters and LASIK surgery [16][17][18]. Exposure to the hot springs has also been reported as a risk factor [19]. Topical steroid therapy can cause localized immunosuppression and thus act as a risk factor [20].…”