DEAR DR. DONOHUE: My family is taking an overseas trip this summer, and we don’t want it to be ruined by diarrhea. I have heard horror stories from people who have visited foreign countries. We have three boys, ages 13 to 17, and they are somewhat hard to control at times. I want to lay down some rules before we leave. Can we take any medicines to prevent it? – M.P.

ANSWER: Where are you going? I could be more specific if I knew. Precautions differ from place to place. In developed countries, the chances of diarrhea are not of the same magnitude as they are in countries where sanitation is more primitive.

Tell the family not to eat raw foods, except for peeled fruits and vegetables. In many places it’s best not to drink tap water or brush your teeth with it. Bottled water is safe. Don’t drink any beverage that is not in a bottle or has not been heated to boiling. Don’t drink unpasteurized milk or eat unpasteurized dairy products. In quite a few countries, it’s a good idea to stay away from street vendors.

Two tablets of Pepto-Bismol taken four times a day is a pretty good way to prevent diarrhea. Xifaxan (rifaximin) is an antibiotic that isn’t absorbed into the body. It works only in the intestinal tract, and it can kill off many diarrhea-producing bacteria.

Further preparation depends on your destination. Your vaccinations must be up-to-date, and you might need special ones for the places you visit. Malaria medicine is necessary when touring countries where malaria is a threat.

There’s a terrific Web site that provides you with all the information you need for just about all countries in the world. It’s sponsored by the Centers for Disease Control and Prevention. It is: www.cdc.gov/travel. If you don’t have a computer, your local library is almost sure to have one and can help patrons use it.

DEAR DR. DONOHUE: My nephew is 6 months old. He has had several transfusions for immune hemolytic anemia. Please tell me what that is. How many transfusions can a baby have? Is there a chance of his catching AIDS from all that transfused blood? – E.V.

ANSWER: Hemolysis is the breaking apart of red blood cells. Anemia is a deficiency of red blood cells. In your nephew’s case, red blood cells are rupturing because they are coated with antibodies – that’s the “immune” part of his illness. The spleen gobbles up antibody-coated red blood cells. Cortisone drugs are often used to slow antibody production. The production might have been turned on by a preceding infection.

Most infants recover from the illness in three to six months.

Your nephew can have as many transfusions as he needs. The danger of contracting AIDS from transfused blood is almost nonexistent, since all blood is tested for the AIDS virus. That wasn’t the case in the days before the test was available.

DEAR DR. DONOHUE: What can be done for boils? My son gets them about three times a year. He is in good health in all other respects. He does not have diabetes. I know you were going to ask that question. – L.L.

ANSWER: Have your son wash daily with an antibacterial soap like Hibiclens.

It’s a chore for you, but he should change washcloths, towels, sheets, undergarments and shirts daily.

People with recurring crops of boils often harbor staph germs – the cause of most boils – in their nostrils, and they spread them to their skin every time they touch their nose. Applying a light coat of mupirocin ointment (Bactroban is one brand name) to the lower, inside of the nostrils can evict any bacteria living there. This is a prescription medicine. If this regimen doesn’t stop the boils, he will need a course of antibiotics.

DEAR DR. DONOHUE: How do kidneys figure into anemia? Mine aren’t working well, and I have to take a drug for the anemia. – R.T.

ANSWER: The kidneys make the hormone erythropoietin, which stimulates red blood cell production. When they aren’t working well, erythropoietin production drops, and anemia results. This substance is available as a medicine.

DEAR DR. DONOHUE: I want to share information with K.A., the woman who hacks her heel calluses with nail clippers.

I have troll feet like hers. I have had heel calluses that cracked, bled and tore the heels out of my stockings. I found a product that has been a miracle cure for me. It is Kerasal water-soluble ointment. It really works.

Your suggestion of shoes with heels that fit your feet perfectly is something that made me laugh. We of the troll feet have feet that are impossible to fit perfectly. I have very long feet with very high arches; little, stubby, gnarly toes; and a narrow heel. “Mildly uncomfortable” is the best fit I can get for my feet. – M.M.

ANSWER: OK, M.M., I trust you. I don’t have any experience with Kerasal, so I’m a bit hesitant to endorse it, but you have made a good case for it. If it doesn’t work, I am referring all readers to you.

How do you know trolls have callused feet with gnarly toes and narrow heels? You could be offending a segment of the population that takes great pride in their feet.

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