DEAR DR. DONOHUE: My granddaughter was recently diagnosed with multiple sclerosis. She soon will be 45. Can you please give me some insight into this disease? I understand that about 400,000 people in the U.S. are afflicted with it. What is happening to find a cure? Is there a national MS society? — R.R.

ANSWER: Nerves are covered with an insulating material called myelin. In multiple sclerosis, the immune system bombards myelin with antibodies, the biological equivalent of hand grenades. The attack leads to a patchy loss of myelin. Nerves are short-circuited. The results depend on which part of the brain and spinal cord come under attack. Initial symptoms can be a loss of sensation of the skin, feelings of pins and needles or pain, a loss of sight in one eye, weakness of a leg or arm, trouble walking, impaired hand dexterity or a loss of bladder control.

The onset can be sudden or more protracted. The most common kind of MS is the relapsing/remitting variety. After the initial attack, all signs and symptoms usually disappear (remit). However, a new attack brings new signs and symptoms. As time goes on, the defects remain more or less permanently.

The illness strikes most often between the ages of 20 and 40, with women being afflicted three times more often than men. It’s more common in temperate climates that have a winter than it is in tropical climates. It may be that the sun’s influence on the skin’s production of vitamin D gives this geographical clustering. Vitamin D is believed to afford some protection against it. Genes have a role. If an identical twin comes down with MS, the other twin has a one in three chance of contracting it. If a parent is involved, the child has a one in 50 chance of developing it.

Prognosis for an individual patient is impossible to predict. Many medicines have only recently been introduced for treatment. They’re not cures, but they do provide a better outlook for patients. One of the cortisone drugs is used for an acute attack. Avonex, Rebif, Betaseron, Copaxone, Gilenya and Novantrone — medicines unheard of a few years ago — have brought about an optimistic outlook for most patients. I assure you that doctor throughout the world are busy looking for a cure.

The National Multiple Sclerosis Society, whose toll-free number is 800-348-4867 and whose website is www.nationalmssociety.org, is a godsend for all patients.

DEAR DR. DONOHUE: I read an article about how antibiotics cause infections in hospitals. I wonder how many bacterial diseases are in a hospital. Can sepsis be contracted there? — L.S.

ANSWER: Antibiotics don’t cause infections except in cases where they kill off good bacteria and permit bad bacteria to proliferate. C. difficile colitis is an example. Unwise use of antibiotics can lead to the generation of supergerms, bacteria that don’t respond to the usual antibiotics. Every hospital has a committee that makes sure this doesn’t happen and makes sure that infections from one patient are not transmitted to another. The number of bacterial diseases in a hospital is large. Hospitals are the refuge for sick, infected patients.

Sepsis is widespread inflammation of body organs due to an infection. Sometimes, the infecting bacteria gain access to the blood, or the toxins (poisons) of bacteria enter the blood as part of sepsis. Body temperature rises, the heart beats faster and breathing becomes shallow and rapid. Blood pressure might drop. Sepsis is a serious condition. It’s often fatal. Yes, it can be contracted in the hospital. All efforts by every hospital are directed to reducing the number of sepsis patients and eliminating sepsis entirely in the best of all worlds. That day should come eventually.

DEAR DR. DONOHUE: I take 2,500 mg of calcium in the form of Citracal (half in the morning and half at noon). How much magnesium should I take with it? — J.W.

ANSWER: You don’t need that much calcium unless your doctor has a reason for suggesting such a dose. The Institute of Medicine, the panel that sets vitamin and mineral requirements, recommends 1,200 mg a day for women over 50 and men over 70. Younger adults are told to take 1,000 mg.

The daily magnesium requirement for adults older than 30 is 320 mg for women and 420 mg for men.

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.