DEAR DR. DONOHUE: If a person has a tapeworm, will it complete its cycle and disappear, or do I need medical attention? Twice I passed something that I thought was food. Several days later, I remembered I never ate anything that wide or flat. One piece was an inch long. Now I think it was part of a tapeworm. — R.M.

ANSWER: Worldwide, tapeworm infections are common. In Canada and the United States, they’re a rarity, due to the close supervision of cattle and pig farming. A microscopic exam of a stool specimen reveals tapeworm eggs. Since eggs are excreted intermittently, it takes more than one specimen. Worm sections, called proglottids — much smaller than an inch — are expelled in the feces and are visible. If you wish, you can have stool specimens tested, but I really doubt that you have a tapeworm. Tapeworms don’t willingly leave an environment that feeds them, keeps them warm and pays their taxes.

Beef tapeworm is acquired by eating undercooked beef that contains the beef tapeworm cysts. Our digestive tracts remove the outer coat of the cyst and permit the larva inside to develop into an adult worm that can attain a length of 33 feet. Although unappetizing to think of, this tapeworm causes few if any symptoms.

The pork tapeworm is acquired in two different ways. One is by eating pork that contains cysts. Like the beef tapeworm, the cyst develops into an adult in the intestinal tract. The pork tapeworm grows to a length of 24 feet. Like the adult beef tapeworm, it produces no great signs or symptoms.

Humans are infected with pork tapeworm in another fashion as well. They ingest the eggs of the tapeworm that have found their way onto foods contaminated with feces of an infected human. This is a serious infection. The egg matures into an intermediate form, which penetrates the digestive tract wall and is carried to the brain, muscles or liver and burrows into these organs to form a cyst. You do not have this kind of tapeworm infection.

Praziquantel and albendazole are two drugs used for getting rid of these tapeworms.

DEAR DR. DONOHUE: I had cataract surgery on both eyes one month ago. I had worn glasses or contact lenses since I was 5. Before the surgery, I even had to use a magnifying glass. Now I can read the newspaper without any aids. What a miracle! My doctor says I need a laser treatment shortly to remove a membrane behind the new lens. What is this? — F.H.

ANSWER: A cataract is a clouded eye lens. The clouding comes from an aggregation of protein material in the lens. Having one is like trying to see through smudged binoculars. The eye lens is located behind the pupil. It’s held in place by a membrane called the posterior capsule. The capsule is left in place to support the new, synthetic lens inserted during surgery. The old lens is taken out. It is a miracle.

After cataract surgery, one-quarter of cataract patients’ posterior capsule membranes become invaded by a growth of cells that obscure vision. That condition is easily cured with a laser beam. It’s a simple procedure most often done in the doctor’s office. You’ll have it completed almost before you take your hat off.

DEAR DR. DONOHUE: My grandson, 14, already has a receding hairline. Is this normal? Is he lacking something? — C.G.

ANSWER: Balding can take place anytime after puberty. Male pattern baldness begins as a recession of hair at the temples and sometimes in the very front. It comes about because of hair follicle sensitivity to male hormones. Have male relatives of your grandson on either the mother’s or father’s side lost hair at an early age? That would answer your question about why it’s happening. The most likely explanation for your grandson’s loss is genes. It’s not likely to occur at such a young age, but, in most cases, it’s not an indication of a sickness or a lack of vitamins or minerals.

If your grandson is concerned, then a visit to the family doctor or a dermatologist can settle the issue. He’s at a very young age to consider treatment, which requires a lifelong commitment.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com.