Demodex mites can cause a blepharitis, by bringing to the surface bacteria (streptococci and staphylococci) at the edge of the eyelid. Moreover, the body deals so infrequently with bacteria in the body that is may then in turn can trigger an immune response (inflammation). The proteins inside the Demodex mites such as their debris or waste can cause a delayed hypersensitivity or an innate immune response and an inflammatory reaction in the host.
Persistent infection of the eyelash follicle can lead to irregular and false eyelash growth (in the wrong direction). If the eyelashes are directed toward the cornea, they may rub on the cornea and cause ulceration.
The blockade of meibomian glands results in swelling and enlargement of the glands; it can also encourage bacteria to create an infection of the glands, resulting in a blockage. This means that the oil from the glands cannot be dispensed. It may also restrict the tear duct from working, which causes further dry eye problems and irritation. The mechanical blockage and the immune reaction at the edge of the eyelid can lead to severe blepharitis. Blepharitis can also spread to the conjunctiva. The Demodex condition that caused conjunctivitis is not treatable by conventional therapy. Even in children with chronic conjunctivitis, which responds to a standard therapy does not need to be thought of a demodex infestation. Inflammation of the eyelid edge can pass to the cornea and cause serious diseases.
Adult D. folliculorum are resistant to a variety of treatments buy you may try 75% alcohol, 10% PVP-iodine, antibiotics such as erythromycin or metronidazole. Some people however will not gain any advantage from these, even after a long exposure time of 150 minutes. Tea tree oil can be used to kill very stubborn mites. Cleaning with tea tree oil not only leads to the removal of the cylindrical scales on the eyelashes, but also means that the mites migrate from the follicles on the skin. A daily cleaning with 50% tea tree oil using a lid massage can lead to falls in mite numbers, to the point where over 4 weeks in most patients, the number of mites is reduced to zero.