A new study has found there may be a link between ocular rosacea and bacteria associated with Demodex mites, microscopic inhabitants of normal skin that tend to occur in much greater numbers in those with rosacea.

In the recently published study of 59 rosacea patients, Dr. Jianjing Li and colleagues at the Ocular Surface Center in Miami found a significant correlation between facial rosacea, infestation of the eyes with Demodex mites and reaction to certain mite-related organisms previously shown to stimulate an immune response in rosacea sufferers.¹

In an earlier study funded by the National Rosacea Society, Dr. Kevin Kavanagh and colleagues at the National University of Ireland-Maynooth found that the bacterium Bacillus oleronius, a distinct bacterium found in Demodex, stimulated an immune system response in 79 percent of patients with subtype 2 (papulopustular) rosacea, compared with only 29 percent of subjects without the disorder.²

In the new study, researchers uncovered the association with ocular symptoms by noting correlations between rosacea patients who had an ocular infestation with Demodex mites (38 subjects) and those in whom B. oleronius stimulated an immune system response (21 subjects). They also noted a borderline correlation between ocular Demodex infestation and eyelid margin inflammation.

The Demodex mites themselves were counted by microscopic examination of lashes, and the presence of the bacteria was determined by serum reaction to proteins they produce.

The researchers pointed out that these findings support the practice of treating subtype 4 (ocular) rosacea with both medication and eye hygiene, including lid scrubbing. They noted that patients may be affected by a combination of factors, including a reaction to the proteins produced by the bacteria, a possible allergic reaction to the mites themselves and other microbes that may have been colonized in the eyelid as a result of the mites.

"Future investigation into this comorbidity between mites and microbes may shed new light not only on the understanding of the pathogenesis of this centuries-old common ailment of the skin and eye, but also other similar unresolved human diseases," the researchers concluded.

References

1. Li J, O'Reilly N, Sheha H, et al. Correlation between ocular Demodex infestation and serum immunoreactivity to Bacillus proteins in patients with facial rosacea. Ophthalmology 2010;117:870-877.
2. Lacey N, Delaney S, Kavanagh K, Powell FC. Mite-related bacterial antigens stimulate inflammatory cells in rosacea. Br J Dermatol 2007;157:474-481.