Q: My husband and I had our eyes checked this month and were both diagnosed with demodex of the eyelashes. We are treating them with eyelid wipes and tea tree oil shampoo. We have two schnauzers. When reading about demodex on the internet, it says it is the cause of mange. Can you give us some information on this? Do we need to treat our dogs, too? They do have crusty eyes in the corners. Thanks so much.
A: Demodex is indeed a mange mite. Otherwise known as demodectic mange, this mite is common in young dogs but also occasionally a problem for cats and humans.
The demodex mite is an eight-legged parasite (technically an arachnid like a spider!) that lives on the surface of the skin. It lives in hair follicles and sebaceous glands of the skin. Of 65 species of this mite, only two are found on humans. Neither one is spread by either dogs or cats.
As you might have noticed by now, there are conflicting reports on the internet about mange being transmissible to humans. Unfortunately, plenty of veterinary websites report that the mite found on cats and dogs is potentially transmissible to humans. But this is simply not so. I have found no scholarly papers that support this contention. All the literature resoundingly refutes the notion that mange in humans comes from either cats or dogs.
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Let me be extra clear on this: D canis and D cati, the species of mange mites found on dogs and cats, respectively, do not infect humans.
In humans, demodex is contracted and spread by either direct contact with other infected humans or with dust containing the eggs of these mites. Which explains why you and your husband both have this mite but your Schnauzers do not.
Interestingly, dogs and cats live in a state of peace with this parasite. Unlike humans, where the mite is considered an unwelcome invader, our pets live with this parasite as a natural member of their skin’s community of microorganisms. In other words, all dogs and cats have demodectic mange mites on their skin.
In dogs, however, this truce doesn’t always hold. For some unfortunate dogs –– puppies, almost exclusively –– this parasite will proliferate and lead to uncomfortable or unsightly signs of disease. This is another issue altogether so try not to stress about it. As always, talk to your veterinarian is you have any lingering doubts.
Dr. Patty Khuly has a veterinary practice at Sunset Animal Clinic in South Miami. Her website is drpattykhuly.com. Send questions to firstname.lastname@example.org.