2017-09-20 / Health

Demodex of eyelashes is caused by tiny mite

DEAR DR. ROACH: What is Demodex of the eyelashes? Can it affect other parts of the body? Is it deadly? — Anon.

ANSWER: Demodex folliculorum is a mite, a small (0.1 mm) arthropod that lives on human skin in hair follicles. There is debate whether they cause disease, specifically inflammation of the eyelids. Most opinions I read suggest they do not. However, there are reports of eye symptoms in some people with more than usual amounts of Demodex, which can be treated with medication. In most people, Demodex is considered part of the normal flora, like the bacteria and fungi we carry around as well.


DEAR DR. ROACH: I am a 75-year-old man who recently experienced three episodes of lightheadedness. After testing, my cardiologist determined that these were not likely to be cardiac in origin. My concern is with the result of my 24-hour Holter monitor, which showed a little more than 1,000 isolated PVCs in 24 hours. I have been told that this is either “dire” or “not an issue.” I would appreciate your comments on this and any discussion of treatment for frequent PVCs. — J.G.

ANSWER: Normally in the heart, the electrical impulse starts at the sinoatrial node, often called the pacemaker of the heart. The impulse proceeds down clearly defined pathways (think of them as wires) to the atrioventricular node, where it waits for the mechanics of the heart to catch up with the electrical system. The electrical impulse then travels down the bundle of His to the Purkinje fibers, which stimulate the ventricle.

Occasionally, in everybody, an electrical impulse will come from a different part of the heart before the normal SA impulse. If it comes from the atria, it is called a premature atrial contraction; and if it’s from the much larger ventricles, a premature ventricular contraction. These are clearly distinguishable on an EKG. A PAC is early and narrow (since the impulse will go through the AV node), while a PVC is early and wide (since it does not, and must travel cell to cell).

My opinion is that frequent PVCs at your level is somewhere between “not an issue” and “dire.” One study showed that people who had no known heart disease but more than 30 PVCs an hour (720 in 24 hours) have an increased risk of heart disease over people with fewer than 30 per hour. The overall increase in risk is not large in absolute terms, however.

Although there is treatment that can reduce PVCs, it’s not clear that this reduces the risk of heart disease, and some treatments actually increase mortality risk. I recommend treatment for frequent PVCs only if there are very bothersome symptoms that are clearly related to the PVCs, or in the very infrequent event of someone with so many PVCs that the fast heart rate damages the heart.

The booklet on abnormal heart rhythms explains the more common heart rhythm disturbances in greater detail. Readers can obtain a copy by writing: Dr. Roach — No. 107W, 628 Virginia Drive, Orlando, FL 32803. Enclose a check or money order (no cash) for $4.75. with the recipient’s printed name and address. Please allow four weeks for delivery.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med. cornell.edu. To view and order health pamphlets, visit www.rbmamall.com.

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