DEAR DR. DONOHUE: My 8-year-old son had what I thought was a cold. About two days into the cold, he broke out in a rash, and I took him to the doctor. The doctor took about two minutes to tell me that my son had a parvovirus infection and that there is no medicine for it. This meant nothing to me, but I got the idea it was not a big deal. I would still like to know more about it. How long does it last? How long does a child have to stay out of school? None of my friends who have small children have heard of it either. – A.R.

ANSWER: Possibly the doctor might have struck a more familiar chord if he had said “fifth disease.” Another name for it is erythema infectiosum. It’s a common childhood infection, occurring mostly in children between the ages of 5 and 15. The cause is the parvovirus.

At the turn of the past century, doctors made a list of five diseases with similar red rashes. Measles, rubella (German measles) and scarlet fever were on that list. The fifth entry on the list was simply called fifth disease.

It’s an infection that goes away on its own; there is no medicine for it. Infected children might start out with cold symptoms and a bit of a temperature rise, but they aren’t very sick. In a day or two, they break out in a characteristic rash that makes the youngster’s cheeks so red they look like they’ve been slapped. The rash spreads to the chest, abdomen, upper arms and upper legs. The rash and the illness are gone in about two weeks.

By the time children break out in a rash, they are no longer infectious. They could go back to school then, but most schools won’t accept them until the rash has gone.

For most children, this is a minor illness. For a few, it is a serious one, with several major complications. Infection in adults takes a much more difficult course than it does in children.

DEAR DR. DONOHUE: I have a friend; we’re both 22. Her father was just diagnosed with hemochromatosis. Her mother called her to tell her to get checked for this illness too. Neither she nor I ever heard of it. Is it rare? How quickly does she have to get the tests? – W.D.

ANSWER: Hemochromatosis (HE-moe-CROW-muh-TOE-siss) is not a rare disease. It’s one of the most common inherited illnesses. It’s a sneaky disease. Although the gene for it is present from birth, signs and symptoms don’t appear until later in life.

Most people’s digestive tract limits the amount of iron they absorb. In a person with hemochromatosis, however, the digestive tract permits too much iron to get into the blood. The excess iron deposits in many organs – heart, pancreas and liver, to mention a few. Iron in the heart leads to heart failure; in the pancreas, to diabetes; and in the liver, to cirrhosis.

Yes, your friend should be tested. She doesn’t have to do this tomorrow, but learning if she has the disease will save her life. If iron is removed from the body at a young age and then throughout life, organs are not damaged. Removal consists in taking blood, the body’s largest storehouse of iron.

DEAR DR. DONOHUE: Please say something about Grover’s disease. I have it. It started as an itchy rash on my chest. I thought it would go away, and it did. However, it came back. That brought me to my doctor, who sent me to a dermatologist. He made a diagnosis of Grover’s disease. Just what is it? – P.C.

ANSWER: Grover’s disease is a newcomer to the dermatologists’ catalog of skin disorders. It was described only 36 years ago. The rash consists of tiny, fragile blisters that break out on the chest, shoulders and upper abdomen. The rash can be mildly itchy or tormentingly so.

Heat, sun and sweat aggravate it. With the coming of winter, you should not be bothered so much by it. Cortisone creams and ointments can usually keep it under wraps.

If you’d like to know the cause, so would doctors.

DEAR DR. DONOHUE: Recently I discussed the treatment of rosacea with a dermatologist, who advised me that many of his patients have obtained relief by eliminating cheese, tomatoes, tea, coffee, wine, chocolate and Mexican, Italian and Thai foods. The Physician’s Desk Reference states that diet probably plays no role in the pathogenesis of rosacea. Can you provide an update on its treatment? What effects does diet have on it? – G.T.

ANSWER: Rosacea (row-ZAY-she-uh) begins as red cheeks and a red tip of the nose. Then the red skin breaks out with pimples, and the same skin sprouts a network of spider-web blood vessels.

Foods and drinks don’t cause rosacea, but some rosacea patients find that the foods your doctor mentioned – as well as alcohol, liver, dairy products, vanilla, soy sauce, vinegar, eggplant, spinach, lima and navy beans, peas, avocados, bananas, and citrus fruits – aggravate the problem. Hot or cold weather, hot drinks, hot baths and hot showers can do the same. Not all rosacea responds to these things adversely. It’s a matter of an individual discovering what foods affect his or her rosacea. Sunlight almost universally makes matters worse, so patients shouldn’t leave their homes without applying sunscreen.

Antibiotic creams and ointments containing erythromycin, clindamycin or metronidazole often control rosacea. Oral antibiotics – tetracycline, erythromycin and metronidazole – are the next step up. The newest medicine is Oracea. It’s a time-release formulation of doxycycline, a tetracycline antibiotic. Its advantage is that blood levels don’t rise high enough to disturb the body’s normal bacterial population with all the troubles that can bring, and it doesn’t, therefore, produce super germs.

Laser treatments are effective for ridding the skin of rosacea’s spider veins.

If you aren’t aware of the National Rosacea Society, become aware. It provides up-to-date information that patients want and need. Its number is 1-888-662-5874 and its Web site is www.rosacea.org.

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